Chemistry doi: 10.3390/chemistry8070088

Authors: Zieryeke Niyazihan Cong Huang Yongbing Huang Junpeng Guo Xingtao Xu

Sustainable water remediation requires catalytic strategies that remove contaminants efficiently while reducing chemical input, byproduct formation, and ecological disturbance. Conventional radical-dominated advanced oxidation processes can rapidly degrade pollutants, but their reliance on high oxidant dosages and freely diffusing reactive oxygen species often causes matrix quenching, non-selective oxidation, low oxidant utilization, and potential ecological risks. Mild interfacial catalysis provides a materials-chemistry strategy to regulate oxidative intensity and direct contaminant transformation under environmentally relevant conditions. In this review, mild catalysts are defined by pathway-selective, interfacially confined, and environmentally compatible oxidation rather than by low dosage alone. Representative non-radical or low-intensity pathways, including singlet oxygen generation, surface-mediated electron transfer, high-valent metal–oxo species, and direct oxidative transfer processes, are discussed in relation to active-site structure, oxidant utilization, matrix tolerance, and byproduct control. We further summarize how coordination environments, defect chemistry, heteroatom configurations, nanoconfinement, and immobilized interfaces regulate reactive-species formation and interfacial charge transfer. Key material platforms, including single-atom catalysts, heteroatom-doped carbons, defect-engineered oxides, catalytic membranes, hydrogels, and floating or immobilized composites, are evaluated from mechanistic and application-oriented perspectives. Finally, catalyst regeneration, cost, microbial community responses, algae–bacteria balance, ecotoxicity, and long-term safety are discussed to guide sustainable aquatic ecosystem restoration.

Chemistry doi: 10.3390/chemistry8070087

Authors: Joaquín Hernández-Fernández Rafael González-Cuello Rodrigo Ortega-Toro

The structure, relative stability, spin-state preference, and preliminary oxygen-release behavior of small nickel–oxygen clusters, (NiO2)n (n = 1–4), were investigated using density functional theory at the M06-2X/def2-TZVP level of theory. Several initial topologies and spin multiplicities were explored to distinguish between dissociated Ni···O2 solutions, bonded dioxo-like arrangements, and side-on metal–dioxygen motifs. For the monomer, the lowest-energy solution of the fully explored set corresponds to a non-bonded Ni···O2 arrangement; however, when the analysis is restricted to chemically bonded NiO2 minima, the linear high-spin O–Ni–O structure is the most stable configuration. The side-on η2-O2 motif was found as a higher-energy bonded minimum, retaining an elongated O–O bond and therefore representing an activated dioxygen-like species. ELF and LOL analyses were used as complementary localization descriptors to distinguish between the electronically separated oxo-like domains of the linear structure and the more coupled localization pattern of the side-on dioxygen adduct. Aggregation from n = 2 to n = 4 suggests a transition from compact bridged motifs to more open Ni–O frameworks. However, the size-dependent trend is discussed only within the explicitly explored conformational space. Preliminary analysis of O2 release from the tetramer indicates that oxygen evolution is not a simple dissociation event but involves substantial structural reorganization. Overall, the results support the view that small (NiO2)n clusters may behave as metastable oxygen-rich intermediates, while also highlighting the strong sensitivity of their energetic ordering to spin state, topology, and structural relaxation.

Chemistry doi: 10.3390/chemistry8070086

Authors: Min Zheng Jianhua Wang Youyi Xun Zisheng Xiao Xiangzhou Li Dulin Yin

Perillyl alcohol, a rare monoterpenoid, can be widely used in chemical, agriculture, and food industries and shows promise in medicine as an anticancer agent. The artificial synthesis of perillyl alcohol from β-pinene epoxide using inexpensive and abundant turpentine is chosen for improving its pharmaceutical and industrial applications. This work presents a green and sustainable catalytic process for the rearrangement of β-pinene epoxide to perillyl alcohol. A novel ammonium phosphomolybdate solid acid (AC-COIMI-NH4PMo) was built via phosphomolybdic acid chemisorption onto an N-basylous site of imidazolized activated carbon followed by ammonia fumigation, which exhibits outstanding catalytic performance in the rearrangement of β-pinene epoxide to perillyl alcohol in nitromethane under mild conditions. At 80 °C over 80 min, nearly complete conversion of the epoxide is achieved with a perillyl alcohol selectivity of 77.3%. Moreover, the used catalyst can be readily recycled after washing with hot nitromethane. The favorable proton-donating capacity of nitromethane for the rearrangement and the comparison of adsorption energies between substrates and main products on ammonium phosphomolybdate are revealed through DFT calculation. Kinetic analysis based on the Langmuir adsorption model indicates that the surface reaction of strongly adsorbed β-pinene epoxide is a rate-determining step and follows a zero-order reaction process; the activation energy is 29.64 kJ/mol within the temperature range of 50–80 °C. Finally, a parallel catalytic rearrangement mechanism is proposed, and an eight-step reaction pathway toward perillyl alcohol is elaborated for β-pinene epoxide conversion on AC-COIMI-NH4PMo.

Chemistry doi: 10.3390/chemistry8060085

Authors: Nandini Chauhan Garima Awasthi Mahipal Singh Sankhla Kumud Kant Awasthi Rajeev Kumar Narendra Kumar Baljeet Yadav Haitham Al Qahtani

Access to clean and safe drinking water for all remains a global challenge, mainly for rural populations and areas affected by natural disasters or humanitarian crises. The traditional water quality treatment technologies can work well in laboratory or controlled settings, but they are usually applied under conditions unavailable in these types of conditions. Traditional water quality treatment methods are limited by established infrastructure, expensive operating costs, energy requirements, and the ability to perform in-field water treatment. To improve the barriers of traditional water quality treatment technologies, recently developed scientific discoveries of nanozymes, a new class of nanomaterials with enzyme-like catalytic activity, have shown the ability to decentralise water purification. Nanozymes provide a mechanism for water treatment that does not require the infrastructure or the cost of traditional water quality treatment methods. Also, nanozymes possess extremely high catalytic activity, chemical stability, are inexpensive, and are suitable for a variety of contaminants. This review gives a systematic overview of the development of suitable nanozyme-based portable water purification systems. It shows their catalytic mechanisms, the class of nanozymes used, and the design characteristics related to their working use, also highlighting the developments that consider the specific needs of rural contexts, provide rapid responses to disaster areas, and offer drinking water with reliable, simple, and sustainable apparatus.

Chemistry doi: 10.3390/chemistry8060084

Authors: Hiroto Tachikawa

The chemical evolution of simple molecules into higher-order structures, such as amino acids, is a fundamental process occurring throughout the cosmos. Methane (CH4) serves as a key precursor in this evolutionary sequence and is prevalent on planetary bodies like Mars and Saturn. In these environments, CH4 is frequently ionized by cosmic radiation, forming the methane radical cation (CH4+). In this study, the ion-molecule reactions between CH4+ and neutral CH4 (CH4+ + CH4 → products) were investigated using direct ab initio molecular dynamics (AIMD) simulations to elucidate the underlying reaction mechanisms. Our calculations demonstrate that proton transfer (PT) occurs efficiently, yielding the methanium ion (CH5+) and the highly reactive methyl radical (CH3): CH4+ + CH4 → CH5+ + CH3. Furthermore, the reaction outcomes exhibit a strong dependence on the impact parameter (b). Collisions at very low impact parameters (b = 0–0.2 Å) resulted in non-reactive, billiard-ball-like scattering. Within the range of b = 0.2–3.0 Å, the formation of a long-lived complex, [CH5-CH3]+, was observed. In the intermediate range of b = 3.0–5.0 Å, a proton-stripping mechanism predominated in PT channel, while collisions at b > 5.0 Å were exclusively non-reactive. The reaction mechanism was qualitatively discussed. These findings provide a detailed atomistic picture of the collision dynamics governing methane-derived molecular evolution in celestial environments.

Chemistry doi: 10.3390/chemistry8060083

Authors: Jiatong Li Qiming Sun Tianyi Zhang Jicheng Ma Dehua Li Shuangxi Xing

The development of highly efficient, stable, and cost-effective non-precious metal electrocatalysts to replace conventional platinum-based materials holds profound significance for accelerating the commercialization of advanced energy conversion devices, such as zinc–air batteries (ZABs). Herein, we propose a facile and highly efficient strategy to prepare a defect-rich, highly active nitrogen-doped porous carbon-based electrocatalyst (denoted U-Fe-N-C, urea-assisted iron–nitrogen–carbon material), via high-temperature co-pyrolysis of heme with urea. Our results demonstrate that urea not only serves as an excellent nitrogen source during pyrolysis, introducing abundant topological defects and heteroatom doping sites, but also induces the carbon substrate to form a hierarchical sponge-like porous structure with a high specific surface area. This unique microenvironment effectively prevents the agglomeration of iron species at high temperatures, achieving enhanced dispersion of iron species stabilized within the nitrogen-rich carbon matrix. Electrochemical evaluations reveal that under the optimal synthesis conditions (a precursor mass ratio of 1:3, calcination at 900 °C), U-Fe-N-C exhibits excellent oxygen reduction reaction (ORR) catalytic performance, delivering a half-wave potential of 0.731 V vs. RHE, and shows long-term operational durability that significantly surpasses that of commercial Pt/C. Furthermore, liquid rechargeable zinc–air batteries assembled with U-Fe-N-C as the air cathode deliver remarkable cycling stability, operating for up to 270 h of charge–discharge cycling without noticeable performance degradation. This study not only provides useful insights into the mechanisms of pore formation and assistance but also offers a practical perspective for the rational design and scalable synthesis of high-performance metal–nitrogen–carbon (M-N-C) electrocatalysts.

Chemistry doi: 10.3390/chemistry8060082

Authors: Zixuan Zhang Huoli Yin Xinchi Qu Guangyun Chen Feng Gao Yixuan Lin Zhuoqian Guo Jingyi Jiao Yuhao Gu Xiaohui Jia Yongji Liu Jincheng Guo Herong Cui Haimin Lei

Background: Acute myocardial infarction (AMI) remains the most lethal critical emergency worldwide. Although Angong Niuhuang Pill (ANP) is an established rescue medicine that has demonstrated outstanding therapeutic potential for cardiovascular diseases, its modern molecular mechanism has never been systematically elucidated because of its chemical complexity and unidentified targets. Methods: This study utilizes a multi-layer analytical pipeline of AI mining, network pharmacology, transcriptomics, and experimental confirmation. The components of ANP were comprehensively identified by UHPLC-Q Exactive Orbitrap HRMS. The TranSiGen algorithm was utilized to deeply mine the data and rank the components according to their relevance to AMI. The top 20 components were selected as prior weights and introduced into network pharmacology for analysis. Subsequently, a mouse model of AMI was established by ligating the left coronary artery. Cardiac function in the mice was evaluated by echocardiography and serum biochemical indicators. The pathological changes in the heart tissue were assessed by hematoxylin-eosin (H&E) and Masson staining. Cardiac transcriptome sequencing was performed, and pathway enrichment was analyzed by KEGG. The key pathways were verified by qPCR and immunofluorescence, achieving cross-validation between AI prediction and experimental findings. Results: The identification of ANP resulted in the detection of a total of 73 compounds, and the TranSiGen algorithm was employed to prioritize these compounds, yielding a ranked list of the top 20 candidates. Functional evaluation using echocardiography, serum biochemical markers, and histopathological examination demonstrated that ANP significantly ameliorated cardiac function in mice following myocardial infarction. Integration of network pharmacology and transcriptomic enrichment identified convergent axes of IL-17 signaling and mitochondrial quality control, which were subsequently experimentally validated as mechanisms by which ANP ameliorated cardiac injury. Experimental validation confirmed that ANP downregulated protein expression of IL-17A and TNF-α, normalized PINK1 and LC3-II/LC3-I marker profiles, with concomitant p62 reduction, thereby providing comprehensive molecular evidence at both transcriptional and translational levels to support the AI-driven predictions. Conclusions: This study identified IL-17 signaling and mitochondrial quality control as pathway axes associated with ANP-mediated cardioprotection against AMI, supported by AI-driven compound screening, transcriptome-network cross-validation, and experimental confirmation. This analytical framework may be adaptable to other complex TCM formulas for mechanism exploration and clinical translation.

Chemistry doi: 10.3390/chemistry8060081

Authors: Zoltán Köntös Máté Varga

We report the synthesis, characterisation and electronic modulation of three novel fused polyheterocyclic ligands—naphtho[1,2-b]furan-4,5-dione (1), furo[3′,2′:3,4]naphtho[1,2-d]imidazole (2), and benzo[a]furo[2,3-c]phenazine (3)—and their Cu(II), Zn(II) and Fe(II/III) complexes. Compound (1) was isolated at 96.5% yield using fulvic acid as a green organocatalyst. 57Fe Mössbauer spectroscopy identified two high-spin Fe(III) environments in a 37:63 ratio (δ = 0.377 mm s−1; Δ = 0.62 and 1.01 mm s−1), with no evidence of magnetically ordered oxide phases. Six enantiomeric metal malate salts were synthesised at 86–93% yield for spectrophotometric titrations. The key finding is a striking Cu(II)-specific enantioselective molecular recognition: (3) binds (S)-(−)-malate Cu(II) with log K = 9.02, a factor of 2.5× higher than the (R)-(+)-malate complex (log K = 8.62), while Fe(II) and Zn(II) show no enantioselectivity. These results establish chiral counter-ion engineering combined with π-conjugated polyheterocyclic scaffolds as a powerful strategy for chiroptical sensing and asymmetric catalysis.

Chemistry doi: 10.3390/chemistry8060080

Authors: Tanja Gerlza Paula Peinsipp Birgit Müller Klaus Thirring Andreas J. Kungl

CXCL8, a pro-inflammatory chemokine, which can be induced by TNF-α or IL-1, is responsible for the recruitment and activation of neutrophils. Chemokines interact with glycosaminoglycans on endothelial cells and are thus protected from degradation and sequestration, holding them in an optimal position for recruiting immune cells. Inhibiting the interaction of chemokines with their glycosaminoglycan co-receptors represents an attractive approach for the treatment of chemokine-mediated diseases. Two polyketide-pyrone compounds, PA501 and PA502 were synthesized, which bind to CXCL8 with affinities higher than the natural glycosaminoglycan ligand heparan sulfate, and in a similar range as heparin. Significant structural changes were induced in the chemokine by interacting with the two compounds, as expressed in fluorescence and far-UV CD experiments. In filter binding assays, both compounds were found to displace heparan sulfate efficiently from CXCL8, with PA501 displaying the highest competition efficacy. Using a C-terminally truncated form of the chemokine, CXCL81-58, which lacks the main glycosaminoglycan-binding α-helical domain, the two compounds are suggested to use—to a varying degree—different binding sites on the protein, which have also been proposed for the natural heparan sulfate ligand. In a transmigration assay, PA501 and PA502 exhibited dose-dependent modulation of CXCL8-induced neutrophil mobilization and migration. The compounds PA501 and PA502 may thus be regarded as early novel lead compounds in the quest for anti-inflammatory, chemokine-targeting drugs.

Chemistry doi: 10.3390/chemistry8060079

Authors: Roman M. Mironenko Vladimir A. Likholobov Aleksandr V. Lavrenov

Currently, the concept of catalyst dynamics, which expresses the phenomena of change in the chemical composition and structure of the catalyst under the action of a reaction medium, has become an integral part of modern catalysis science. However, for the view of the catalyst as a dynamically changing component of a catalytic system to become generally accepted, the catalysis science had to come a long way. The present review provides a retrospective analysis of the development of catalysis with the aim of finding out at what point and under what circumstances the ideas about the dynamic nature of catalysts arose, were experimentally confirmed, and how they were further elaborated. The results of this analysis indicate the universal nature of dynamic catalytic phenomena, which inevitably raises the question of considering them from a broad and unified perspective.

Chemistry doi: 10.3390/chemistry8060078

Authors: Guliya R. Nizameeva Viktoria V. Vorobieva Elgina M. Lebedeva Ruslan M. Sarimov Irek R. Nizameev Oleg G. Sinyashin

In this work, the effect of chitosan concentration in chitosan/nickel composite coatings on their morphology and electrocatalytic activity in hydrogen evolution reaction (HER) was investigated. A series of Chitosan/Ni coatings with chitosan content from 0 to 0.7 wt.% was obtained by nickel electrodeposition onto a preformed biopolymer matrix, enabling targeted control of the roughness and specific surface area of the nickel layers. Morphology and roughness parameters were studied using atomic force microscopy and confocal microscopy. Electrochemical activity in the HER was examined by linear sweep voltammetry. Among the studied electrocatalysts, the Chitosan(0.6)/Ni system showed the best HER efficiency, with an overpotential of −200 mV at a current density of 10 mA/cm2. Electrochemical impedance spectroscopy was used to determine the real surface area of the coatings. The Chitosan(0.6)/Ni sample exhibited the largest surface area, explaining its high HER activity. The obtained data revealed a correlation between chitosan concentration, composite morphology, and electrochemical activity, and allowed determination of the optimal composite composition. The results demonstrate the potential of chitosan as an effective structural modifier of nickel coatings and open up possibilities for the targeted design of composite materials with tailored electrochemical properties.

Chemistry doi: 10.3390/chemistry8060077

Authors: Subhayan Das Pal Yukta Sao Sujeet Kumar Nishith Teraiya Basavaraj Metikurki Shankar G. Alegaon Sanjana S. Prakash Gururaj Kudur Jayaprakash Subhas S. Karki

A series of 1,2,3-triazole-linked-thiazolidine-2,4-dione hybrids (SDP1–SDP15) were designed, synthesized, and evaluated for their antidiabetic potential. All structures were characterized by FT-IR and NMR spectroscopy (1H and 13C). All derivatives exhibited significant in vitro inhibition of α-glucosidase (IC50: 24.17–46.41 µg/mL) and α-amylase (23.25–50.66 µg/mL), comparable to the standard drug acarbose (IC50: 25.18 and 32.53 µg/mL) and superior to the reference drug pioglitazone (IC50: 84.24 and 79.74 µg/mL) for α-glucosidase and α-amylase, respectively. Molecule SDP8 emerged as the most potent with an IC50 of 24.17 and 23.25 µg/mL for α-glucosidase and α-amylase, respectively. Further, SDP8 exhibited a higher docking score of −10.7 kcal/mol and −10.4 kcal/mol against α-glucosidase and α-amylase than pioglitazone (−8.1 kcal/mol and −7.7 kcal/mol, respectively), suggesting that interaction with these two enzymes may be the cause for its antidiabetic activity. Furthermore, DFT analysis revealed favorable electronic properties with a low HOMO-LUMO energy gap, whereas ADMET predictions revealed moderate drug-like characteristics with some limitations, such as poor solubility, relatively high lipophilicity, and partial noncompliance with drug-likeness regulations. Overall, these results highlight triazole-linked thiazolidinedione hybrids as promising candidates for further development in T2DM, with SDP8 serving as a preliminary lead requiring additional optimization and validation.

Chemistry doi: 10.3390/chemistry8060076

Authors: Patrick Masson Andrey V. Nemtarev Tatiana Pashirova Samaneh Hajimohammadi Vladimir Mironov

Cholinesterases (ChEs) are irreversibly inhibited by organophosphorous compounds (OP). Then, OP-inhibited ChEs undergo a reaction that progressively decreases reactivatability. This process called “aging” results from dealkylation of the adduct. Aged ChEs are resistant to antidotal oximes. Structural and conformational changes in the aged phosphylated ChE active site pocket impair enzyme reactivatability. Thus, reactivation of aged ChEs was a challenge for more than 70 years. However, it was postulated that realkylation of aged adducts could lead to reactivation of enzymes. This hypothesis was confirmed in 2018 when a new generation of reactivators, electrophilic quinone methide precursors (QMPs), capable of resuscitating or resurrecting aged ChEs were synthesized. The QMP-mediated resurrection process of ChEs by these first “resurrectors” is still very slow. Thus, substantial optimization in the chemical design of new drugs and drug-targeted delivery are needed before the resurrection approach can be translated into clinically viable therapies. However, despite limitations, the first achievements resolving the non-reactivatability issue of OP-aged cholinesterases and successful administration of these new reactivators can be regarded as a major step forward in improving the therapy of OP poisoning.

Chemistry doi: 10.3390/chemistry8060075

Authors: Menghao Ren Rongheng Gou Hanyu Chen Tian-Min Wu Shansong Gao Dao Li Haisheng Li Qing Zheng Yanjun Zhang

Understanding the atomic-scale mechanisms of coal pyrolysis is essential for efficient coal utilization and carbon-neutral energy strategies, yet conventional computational approaches often struggle to balance between the high accuracy of quantum-chemical calculations and the efficiency of reactive force fields. To overcome this limitation, we proposed a multiscale computational framework integrating high-throughput density functional theory (DFT) calculations, ReaxFF-based configuration sampling, YARP reaction enumeration, and DPA3-based machine learning potentials (MLPs). Two coal-specific MLPs, DPA3-coal and DPA3-coal@dftb, were constructed and systematically benchmarked on both small molecular systems and larger C20–30 coal fragments extracted from MD simulations. DPA3-coal@dftb model demonstrated significantly improved accuracy over ReaxFF in predicting energies and atomic forces while maintaining good transferability. To balance computational efficiency and accuracy in large-scale simulations, the DPA3-coal model was employed to perform accelerated reactive molecular dynamics simulations of a Solomon-type bituminous coal molecule from 1600 to 2600 K. The simulations revealed temperature-dependent evolution of coke, tar, and gas products, including secondary condensation and deep-cracking processes at elevated temperatures. Higher-level DFT calculations further confirmed the thermodynamic consistency of key reaction pathways involving radical formation, H-transfer, recombination, and CO generation, indicating that coal-specific MLPs provide an effective atomistic tool for investigating mechanistic trends in coal pyrolysis.

Chemistry doi: 10.3390/chemistry8060074

Authors: Cheng Wang Guohua Liu Chunxia Tan

Photocycloaddition reactions provide an efficient strategy for converting alkenes into structurally complex and high-value molecules that are often difficult to access under conventional thermal conditions. Herein, two readily accessible triarylamine-based imine molecular cages possessing distinct cavity environments were investigated as supramolecular photocatalysts for reactions of pyridinium-masked enol (PME) substrates with unactivated alkenes. Spectroscopic studies are consistent with the formation of electron donor–acceptor (EDA) interactions between the electron-rich cage frameworks and electron-deficient PME substrates. Upon blue-light irradiation (450 nm), these charge-transfer assemblies undergo photoinduced activation, likely involving single-electron transfer, N–O bond cleavage, and subsequent radical generation. The resulting radical intermediates participate in formal [4 + 2] cycloaddition reactions to afford tetralone derivatives under metal-free conditions. Comparative studies revealed that the two cages produce distinct product distributions and selectivities, suggesting that subtle variations in cage architecture and confined supramolecular environments influence the fate of reactive radical intermediates and the balance between productive cyclization and competing side pathways. While the detailed mechanistic origin of these effects remains unresolved, this work demonstrates the potential of covalent organic cages as structurally tunable platforms for modulating EDA-mediated photochemical reactivity and radical selectivity.

Chemistry doi: 10.3390/chemistry8060073

Authors: Abdulrhman F. Al-Hakim Zainab A. K. Al-Messri

Lubricants contain various types of additives, with corrosion and rust inhibitors being some of the most important. Due to the importance of 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) in the field of corrosion inhibitors, we used it as a key intermediate to synthesize a series of 4-thiazolidinone and 4-imidazolidinone derivatives. This work also includes performing the reaction of DMTD with ethyl chloroacetate, which produced the corresponding ester, followed by the conversion into a hydrazide derivative using hydrazine hydrate. The next step is the condensing of the yielded hydrazide with various aromatic aldehydes yielding Schiff bases, which were subjected to cyclization by means of mercapto acetic acid and ethyl glycinate to produce the target 4-thiazolidinone and 4-imidazolidinone derivatives, respectively. FT IR, 1H NMR, and 13C NMR spectroscopies were involved to confirm the structures of these derivatives. The synthesized derivatives have been evaluated as copper corrosion and rust inhibitors for medium lubricants in accordance with ASTM-D130 and ASTM-D665 standards. Interestingly, some lubricant blends of the synthesized derivatives showed good performance as copper corrosion and rust inhibitors.

Chemistry doi: 10.3390/chemistry8060072

Authors: Sofia M. Sousa Ana I. Rodrigues Fátima Baltazar Marta Costa Fernanda Proença

Chromene derivatives are important structural motifs in biologically active compounds and functional materials, and the development of efficient strategies for their synthesis remains of considerable interest. In this work, simple and sustainable methodologies were developed for the synthesis of chromene dimers linked through short amidine/geminal diamine spacers or long, flexible alkyl diamine linkers. The amidine and geminal diamine linkers were obtained from 3-aminochromene derivatives via nucleophilic addition of the amino group to triethyl orthoformate or non-phenolic aldehydes in ethanol, at room temperature or under reflux, affording the corresponding dimers in moderate to very good yields. In a complementary approach, flexible alkyl diamide linkers were prepared from diamines and ethyl cyanoacetate, followed by condensation with salicylaldehydes in aqueous hydrogen carbonate solution and subsequent acidic hydrolysis, leading to new chromene dimers in excellent yields. These mild and operationally simple protocols provide efficient access to structurally diverse chromene dimers with potential applications in medicinal chemistry and materials science.

Chemistry doi: 10.3390/chemistry8060071

Authors: Mike Seed Philipp I. Schodder Marco Schmidt Hesham Abdallah Mikko Hofsommer Simon Kelly Jan Hartwig

Apple juice is one of the world’s most widely consumed fruit juices and is therefore a common target for economically motivated adulteration (EMA). Such adulteration may involve dilution with water, substitution with other juices, or the addition of exogenous sugars, each requiring robust analytical methods for detection. In this study, we present an improved analytical method for identifying exogenous C4-type sugars in apple juice which utilizes the naturally occurring sorbitol as an endogenous isotopic reference marker. The method uses liquid chromatography coupled to isotope ratio mass spectrometry (LC-IRMS) to determine the δ13C values of the major endogenous sugars in apple juice. The study shows that the δ13C value of sorbitol can be measured in the same analytical run as the other major sugar components and remains unaffected by the addition of exogenous C4-type sugars to the apple juice. This method offers significant advantages over existing approaches, notably by eliminating the need for extensive sample preparation and multiple analytical methods thereby improving both analytical throughput and ease of use.

Chemistry doi: 10.3390/chemistry8060070

Authors: Mohammed A. A. Elshaer Mervat El-Hefny Shimaa E.-S. I. Hassanien Gamal S. Alfawal Waled Abd-Elhamed Mohamed A. M. Abd-Elraheem Abeer A. Mohamed Ayman S. Taha Tartil M. Emam

Several bioactive compounds, including phenolic and flavonoid substances, have been identified in the aqueous leaf extract of Schinus terebinthifolius (ALE). These compounds are active ingredients in green nanoparticle biosynthesis. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), zeta potential analysis, and FTIR spectral analysis were used to characterize copper oxide nanoparticles (CuNPs) and silver nanoparticles (AgNPs). According to TEM results, AgNPs exhibited somewhat larger diameters (12 ± 4 nm), were spherical with significant aggregation, and displayed a fairly uniform distribution, while CuNPs were primarily quasi-spherical with a narrow size range of about 4–5 nm. CuNPs showed a much more negative zeta potential value of −25.8 mV, indicating good to high colloidal stability, whereas AgNPs had a zeta potential of −15.5 mV, suggesting moderate stability. The main compounds included chlorogenic acid (10,375.28 µg/g), gallic acid (7015.59 µg/g extract), ellagic acid (1571.29 µg/g extract), and rutin (1485 µg/g extract). The antifungal activity of CuNPs and AgNPs was tested at concentrations of 6, 12, 25, 50, and 75 μg/mL on Quercus rubra wood against Fusarium circinatum and Pythium tardicrescens. The greatest inhibition of F. circinatum growth was observed with CuNPs and AgNPs at 75 µg/mL, showing fungal inhibition percentages (FIPs) of 61.48 and 60.74%, respectively. CuNPs and AgNPs at 75 µg/mL exhibited moderate activity against P. tardicrescens, with FIPs of 21.48% and 15.92%, respectively. The MICs for AgNPs and CuNPs were 1.5 and 85 µg/mL with F. circinatum and P. tardicrescens, respectively. Overall, CuNPs and AgNPs demonstrated potential antifungal activity against F. circinatum but moderate activity against P. tardicrescens compared to the control. This ALE from S. terebinthifolius is rich in flavonoids and phenolic compounds, including gallic acid, chlorogenic acid, rutin, ellagic acid, and p-coumaric acid, as identified by HPLC analysis. These biomolecules act as both capping agents, which stabilize the nanoparticles, and reducing agents. Using S. terebinthifolius ALE’s rich phytochemical profile as a reducing and stabilizing agent provides an environmentally friendly method for the green synthesis of CuNPs and AgNPs.

Chemistry doi: 10.3390/chemistry8050069

Authors: Philip Asare J. Jesús Velázquez Salazar Miguel José Yacamán

The catalytic reduction of 4-nitrophenol (4-NP) requires highly efficient and cost-effective materials, making Mn-Ni nanostructures a promising candidate. In this study, Mn-Ni nanoparticles with distinct morphologies (specifically spheres, stars, and core–shell structures) were synthesized by tuning the precursor composition. The structural and optical properties of the synthesized catalysts were characterized via electron microscopy and UV-Vis spectroscopy. Kinetic evaluations of the 4-NP reduction demonstrated that the core–shell architecture yielded the highest catalytic activity, outperforming both the star-shaped and spherical nanoparticles. Furthermore, the high-index facets at the tips of the nanostars appeared to have contributed to enhanced catalytic activity by providing additional active surface sites for the reduction process. Ultimately, this work suggests that structural morphology and interfacial interactions play important roles in determining catalytic performance, rather than absolute surface area, providing valuable insights into the design of future bimetallic catalysts.

Chemistry doi: 10.3390/chemistry8050068

Authors: Itumeleng Lucky Mongadi Nomasonto Rapulenyane Walter Bonke Mahlangu Jean-Nazaire Oyourou

This study investigated the application of six machine learning regression algorithms such as Random Forest, CatBoost, K-Nearest Neighbours, XGBoost, LightGBM, and Gradient Boosting, paired with Molecular ACCess System (MACCS) key fingerprints for the quantitative prediction of aromatase (CYP19A1) inhibitory potency, expressed as pIC50. A dataset of 187 compounds was assembled from the ChEMBL database (version 33, Target ID: CHEMBL1978) following by systematic data curation workflow encompassing duplicate removal, pIC50 transformation, and activity-based filtering. Model performance was rigorously evaluated using an 80/20 stratified train/test split, 5-fold cross-validation, and Y-randomisation testing to ensure unbiased assessment of predictive generalisation. Feature selection via CatBoost permutation importance on the held-out test set identified the top 20 predictive MACCS keys from an initial 166-bit space, substantially reducing dimensionality and improving generalisation across all models. Among the algorithms evaluated, CatBoost trained on the top 20 features achieved the strongest test-set performance (R2 = 0.693, RMSE = 0.794, MAE = 0.659) with the most stable cross-validation R2 (0.062 ± 0.304), outperforming all other algorithms. Y-randomisation testing returned an empirical p-value of <0.01, confirming that model performance reflects genuine structure–activity relationships rather than statistical chance. Permutation importance and SHAP analysis identified nitrogen-containing heterocyclic fragments (MACCS_41, MACCS_145) and halide-bearing substructures (MACCS_109) as the primary structural determinants of aromatase inhibitory potency, consistent with established CYP19A1 pharmacophoric requirements. Application of the model to ten representative plasticizers demonstrated that the refined applicability domain (h* = 0.423) accommodated eight of the ten compounds, enabling reliable potency predictions across phthalate esters and bisphenol analogues. These findings establish a transparent and reproducible QSAR framework for first-tier endocrine disruption risk screening of plasticizers and highlight the importance of permutation-based feature selection and applicability domain assessment in QSAR model development.

Chemistry doi: 10.3390/chemistry8050067

Authors: Nikola Maraković

As key therapeutic targets for symptomatic treatment of Alzheimer’s disease (AD) according to the cholinergic hypothesis, acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8) have been the subject of numerous studies over decades, leading to large collections of different ligands with corresponding AChE and BChE activity. This vast amount of data provides an ideal basis for the implementation of different machine learning (ML) and deep learning (DL) tools in different steps of the drug discovery process. Mainly applied to identify potential strong inhibitors of AChE and to a lesser extent BChE, many quantitative structure–activity relationship (QSAR) models and other predictive tools have been constructed utilizing different ML algorithms and DL techniques with various success depending on the input data and specific context. Here, we provide an extensive overview of such cases reported in the literature in recent years.

Chemistry doi: 10.3390/chemistry8050066

Authors: Jing Xie Caoran Li Shansong Gao Zhening Chen Rongheng Gou Lei Gong Xiangfeng Yu Dao Li

Direct Coal Liquefaction (DCL) is a promising route for converting abundant coal resources into liquid fuels, yet its efficiency remains strongly dependent on catalyst performance. In this work, we present an integrated computational framework combining density functional theory (DFT) calculations with machine learning (ML) to investigate iron–sulfur (FeS) cluster catalysts for DCL. DFT calculations were employed to examine hydrogen-donor dissociation and coal-derived radical hydrogenation on representative FeS clusters. The results indicate that the most favorable catalytic pathways arise from the cooperation between metallic Fe sites (Fe_2) and interfacial Fe sites adjacent to sulfur (Fe_1), while sulfur atoms mainly play an indirect structural and electronic modulation role. Based on these mechanistic insights, a database containing thermodynamic and kinetic data for 636 reactions across 50 FeS cluster models was constructed. This dataset was then used to train three ML classifiers, among which the Random Forest model showed the best performance, reaching accuracies of 80% for H-donor cleavage and 93% for radical hydrogenation on the held-out test sets. SHapley Additive exPlanations (SHAP) analysis further showed that descriptors associated with Fe active-site identity were among the most influential variables in both tasks. Overall, this work provides a mechanistically informed and interpretable computational framework for understanding FeS-catalyzed DCL chemistry and for the preliminary screening of catalyst motifs within the chemical space covered by the present FeS cluster library.

Chemistry doi: 10.3390/chemistry8050065

Authors: Tan Ke Rozaimy Abdul Rahim Noor Hazfalinda Hamzah Normah Awang Atikah Mohd Nasir

The escalating threat of antibiotic resistance, driven by the persistence of tetracycline in aquatic ecosystems, necessitates the development of advanced remediation platforms with high structural efficiency. In this study, a bimetallic Ag-Fe co-doped ZIF-8 framework was strategically engineered to optimize pore accessibility and surface chemical affinity. The resulting nanocomposite exhibited an ultra-high BET surface area of 1322.64 m2/g and a pore volume of 0.502 cm3/g, while maintaining the characteristic structural integrity of the parent ZIF-8. Adsorption benchmarks demonstrated a superior maximum capacity of 417.97 mg/g at pH 8 under ambient conditions. The sequestration process was found to be governed by pseudo-second-order kinetics, while the Freundlich and intraparticle diffusion models accurately described a multilayer adsorption mechanism occurring across heterogeneous active sites. Furthermore, the Ag-Fe-ZIF-8 maintained its structural stability and performance over three consecutive cycles. These findings highlight the potential of bimetallic ZIF-8 derivatives as robust, high-surface-area platforms for the sustainable removal of pharmaceutical pollutants from wastewater, with an adsorption capacity as high as 417.97 mg/g after 3 h.

Chemistry doi: 10.3390/chemistry8050064

Authors: Manyao Wang Zongyu Huang Yang Chen Xiang Qi

In the post-Moore era, large-area manufacturing of high-quality two-dimensional (2D) materials remains a central bottleneck for the industrialization of next-generation microelectronic and optoelectronic devices. Conventional mechanical exfoliation is limited by randomness and small lateral size, whereas chemical vapor deposition inevitably introduces grain boundaries, stress, and interfacial contamination, making it difficult to achieve both high quality and scalability. Metal-assisted exfoliation (MAE) enables controllable exfoliation and nondestructive transfer of large-area, high-quality monolayer 2D materials via precise modulation of metal-2D interfacial interactions dominated by strain-induced decoupling and atomic intercalation. This article systematically outlines the interfacial physical mechanisms and technological evolution of MAE, and highlights its state-of-the-art applications in patterned transfer, high-performance field-effect transistors, and complementary logic circuits, aiming to provide a firm theoretical and technical basis for advancing 2D materials from fundamental research toward practical applications.

Chemistry doi: 10.3390/chemistry8050063

Authors: Mateus T. Silva Breno N. Matos Moacyr J. B. Melo Rego Tais Gratieri Marcilio Cunha-Filho Guilherme M. Gelfuso

The combination of gemcitabine (GEM) and olaparib (OLA) shows promise for treating pancreatic cancer, particularly in patients with mutations in the BRCA genes. This work presents the validation of a straightforward, fast, and sensitive chromatographic method for the simultaneous analysis of GEM and OLA, supporting the development of advanced pharmaceutical formulations that combine the two drugs. The efficient chromatographic separation of GEM and OLA was achieved using a C18 column (250 × 4.6 mm, 5 μm) with a mobile phase composed of acetonitrile and water (50:50, v/v), which eluted isocratically at a flow rate of 0.8 mL/min. Determinations were performed using a PDA detector at 243 nm for both drugs. The retention times for GEM and OLA were approximately 3.3 and 4.3 min, respectively. The method was linear (R2 > 0.999), with a regression curve in the concentration range of 0.5 to 10.0 μg/mL, demonstrating sensitivity, precision, and accuracy. The recovery rates of the drugs from the pancreatic tissue were higher than 97.0%. The components of a coated liposomal formulation and the pancreatic tissue did not interfere with the analysis, and both drugs demonstrated a low degradation rate under stressful conditions. In conclusion, the validated method was suitable for quantifying GEM and OLA simultaneously, even in a biological matrix, making it feasible to support the development of advanced pharmaceutical formulations that incorporate both drugs, such as liposomes.

Chemistry doi: 10.3390/chemistry8050062

Authors: Dalin Wang Mingyang Yan Fang Chen Jianjia Huang Dongzhong Chen

Phosphorus is an indispensable key element in life systems and materials science. Here in this work, several cyanoterphenyl-based phosphinic acid-bridged liquid crystal (LC) dimers of 2(CTOn)P (n = 6, 11) and their methyl esterification derivatives of 2(CTOn)P1E have been synthesized through hydrophosphination reaction followed by Suzuki coupling. The cyanoterphenyl LC dimers of 2(CTOn)P and methyl esterified 2(CTOn)P1E exhibit rich enantiotropic LC mesophases such as nematic (N), smectic A (SmA) and highly ordered smectic E (SmE), rather than the monotropic N or twist bend nematic (NTB) displayed by the analogous phosphinic acid-bridged cyanobiphenyl LC dimers of 2(CBOn)P as reported previously. The phase transition temperatures of the cyanoterphenyl LC dimers 2(CTOn)P are also significantly higher than those of the cyanobiphenyl series, which is attributed to the larger π-conjugated system of cyanoterphenyl as compared with cyanobiphenyl, resulting in much enhanced π-π stacking interactions. However, the significantly enhanced interactions also make them extremely insoluble; thus, a different two-step synthesis pathway combining hydrophosphination with Suzuki coupling reactions was adopted. It is worth pointing out that by combining multiple characterization techniques, including DEPT 135°, 13C NMR, and HR-MS spectra, the definite molecular composition and structure of a byproduct with a third pro-mesogen attached via a branching alkyl spacer has been unambiguously demonstrated, which evidently deepens our understanding of the free radical-mediated hydrophosphination reaction mechanism, thereby providing valuable guidance for diminishing side reactions and achieving well-preparation of the high-purity phosphorus-containing LC dimers. Such phosphinic acid functionalized LC materials are envisioned to bear some unique application prospects.

Chemistry doi: 10.3390/chemistry8050061

Authors: Iván Balderas-León Martha Reyes-Becerril Martín Zermeño-Ruiz Luis Miguel Anaya-Esparza Ian Vitola Omar Fabela-Sánchez Carlos Arnulfo Velázquez-Carriles Miguel Ángel López-Álvarez Azucena Herrera-González César Ricardo Cortez-Álvarez Jorge Manuel Silva-Jara

Developing eco-friendly metal oxide nanoparticles (NPs) with plant-based reducing and stabilizing agents offers a sustainable alternative to traditional chemical methods. Nonetheless, the detailed mechanisms by which phytochemicals influence NPs formation, antimicrobial properties, and cytocompatibility remain poorly understood, especially in systems mediated by Vaccinium. This study aimed to synthesize TiO2 NPs and ZnO NPs using Vaccinium corymbosum (blueberry) extract, analyze their structural and surface characteristics, assess their antimicrobial effectiveness and cytotoxicity, and explore potential molecular mechanisms through computational docking. ZnO NPs were produced via alkaline precipitation (pH 12) from ZnCl2, while food-grade TiO2 was mixed with blueberry extract. A comprehensive characterization was carried out using techniques like X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission and scanning electron microscopy (TEM/SEM), dynamic light scattering (DLS), and high-performance liquid chromatography (HPLC) for polyphenol profiling. The antimicrobial activity was tested against Escherichia coli and Salmonella Typhimurium, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. Cytotoxicity was assessed using Gallus gallus domesticus leukocytes and Artemia salina bioassays, and molecular docking simulations were performed to examine polyphenol interactions with the bacterial DNA gyrase subunit B (GyrB). XRD analysis confirmed the presence of wurtzite ZnO (with a crystallite size of 18.2 nm) and anatase TiO2 (12.8 nm after functionalization). HPLC identified key polyphenols, including quercetin, cyanidin, malvidin, and cyanidin-3-glucoside, with patterns indicating stronger adsorption onto TiO2 NPs surfaces. ZnO NPs showed higher antimicrobial effectiveness (>90% inhibition at 2 mg/mL; MIC 0.5–1 mg/mL) compared to TiO2 (72% inhibition at 16 mg/mL; MIC 8–16 mg/mL). Cytotoxicity results indicated concentration-dependent effects. Molecular docking simulations revealed favorable binding energies (−6.2 to −8.4 kcal/mol) for blueberry polyphenols with GyrB, suggesting potential synergistic antimicrobial effects and ROS production. The study highlights a successful green synthesis of bioactive TiO2 NPs and ZnO NPs using Vaccinium corymbosum extract, where polyphenol surface functionalization enhances both colloidal stability and biological activity. This comparative research offers mechanistic insights into how polyphenol-coated NPs work and supports the development of eco-friendly antimicrobial oxide nanomaterials.

Chemistry doi: 10.3390/chemistry8050060

Authors: Hefei Yang Chang-Sheng Kuai Chao Xu Xiao-Feng Wu

This study presents an efficient and environmentally friendly route for synthesizing succinic acid derivatives via palladium-catalyzed oxidative dicarbonylation of ethylene, utilizing oxygen as the terminal oxidant. By systematically optimizing reaction parameters—including catalyst composition, solvent volume, gas ratio, temperature, and additives—the turnover number (TON) for dimethyl succinate was significantly enhanced to 10,325. This strategy not only demonstrates the potential of CO and ethylene as simple and abundant C1 and C2 building blocks but also highlights the viability of oxygen as a sustainable oxidant. The developed process offers a promising pathway toward the cost-effective and scalable production of biodegradable materials such as poly(butylene succinate) (PBS), with important implications for advancing green synthesis and enabling an autonomous supply chain in the biodegradable polymer industry.

Chemistry doi: 10.3390/chemistry8050059

Authors: Trevor Dvorak Sara Fox-Belmonte Noah Burbul Haishi Cao

A series of morpholine-appended 1,8-naphthalimide probes (S1–S5) was developed to investigate the influence of the morpholine moiety on H2S detection. All probes exhibited characteristic absorption and emission features and responded to H2S with fluorescence enhancement, although the intensity varied markedly across the series. S2 displayed the highest signal enhancement, while S5 showed minimal response, highlighting the critical role of a two-carbon spacer between the morpholine group and the fluorophore for optimal sensing. Kinetic analysis revealed that S1–S4 followed similar reaction profiles, whereas S5 reacted faster but produced a weaker signal. S2 maintained reliable performance across pH 4–9 and in DMSO-containing media and demonstrated excellent selectivity over common biothiols and other potentially interfering species. These findings provide a clear structure–activity relationship for morpholine-based fluorescent probes and inform the rational design of highly selective H2S sensors.

Chemistry doi: 10.3390/chemistry8050058

Authors: Zarema Zarafutdinova Artemiy Shmelev Alexey Dovzhenko Guliya Nizameeva Elena Bulatova Alexey Strelnik Vladimir Evtugin Sufia Ziganshina Rustem Zairov Erika Gaifullina Rustem Amirov Anna Ziyatdinova

This work presents an energy-efficient and simple method for producing luminescent, antibacterial sulfur quantum dots (SQDs). For the first time, polyethyleneimine (PEI)-coated SQDs were synthesized via a mechanochemical technique, utilizing either elemental sulfur or sodium thiosulfate as the sulfur source. The roles of hydrogen peroxide (H2O2) as an etching agent and of sodium hydroxide (NaOH) in the PEI-mediated SQD formation were investigated. The as-synthesized SQDs were characterized by UV-visible, Raman, infrared (IR), and photoluminescence (PL) spectroscopy, as well as by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Both TEM and AFM analyses revealed similarly small SQD sizes (average diameter ~3 nm), independent of the sulfur source used. The influence of synthesis conditions on the optical properties, including the photoluminescence quantum yield (QY), was evaluated. SQDs derived from elemental sulfur, PEI, and NaOH exhibited the best water solubility and the strongest photoemission in the 400–550 nm range. Antibacterial activity was assessed against representative Gram-positive and Gram-negative strains, and minimum inhibitory concentration (MIC) values were determined. The PEI-coated SQDs demonstrated antibacterial activity against the Gram-positive bacteria Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis, which is attributed primarily to the sulfur component.

Chemistry doi: 10.3390/chemistry8050057

Authors: Emily Preedy Darren L. Oatley-Radcliffe José Gayo Pelaez Gahtan S. M. Algahtani Jack H. Wade Andrew R. Barron

Despite the extensive literature on microalgal production, most studies focus on controlled laboratory-scale systems, resulting in a critical lack of confidence at industrial scale. This is further compounded by the frequently observed inconsistencies, with only modest increases achieved in operational scale. This work demonstrates the design, construction, and operation of a commercial-scale tubular photobioreactor and associated equipment for the production of algae using CO2 derived from an industrial nickel refinery. The reactor was demonstrated by growing the species Nannochloropsis gaditana. Biomass concentrations of 1.0 to 1.3 g L−1 were achieved with a productivity of 0.11 g L−1 d−1. Extrapolation to a 300-day production year showed that the reactor was capable of producing 541.2 kg algae and sequestering around 1 tonne of CO2. A technoeconomic assessment showed that the total plant CAPEX was £583,905 and the OPEX was £98,196. Sales of algae alone showed poor economic performance. However, economic favourability is observed for species that contain phycocyanin pigment and yield a positive net present value within 4 to 7 years based on recovery yield. This work effectively provides reliable process data developed at scale that can be used to formulate business cases for further scale-up and expansion of algal production systems. This moves the technology a step closer to full-scale realisation and the potential for a net-zero, sustainable future.

Chemistry doi: 10.3390/chemistry8050056

Authors: Huan Yi Xiaoshuai Wang Junjie Yang Yanjie Fang Shaolong Huang Zhengyuan Jin Ribao Feng

An effective strategy for significantly enhancing photocatalytic activity of composite materials is to construct heterojunctions. Herein, a series of imidazole-modified heterostructured g-C3N4/SnO (CNIS) Z-scheme photocatalysts were prepared by calcination methods, leading to superior photocatalytic performance than pure SnO and imidazole-modified g-C3N4. Rhodamine B (Rh B) aqueous solution was taken as the target pollutant, and the result presented that both imidazole modification and the Z-scheme heterojunction construction benefited from significant enhancement in photocatalytic activity. Moreover, it is revealed that electrons were transferred from imidazole-modified g-C3N4 to SnO through the interface of the composite by XPS analysis. Under visible light (>420 nm) irradiation, the built-in electric field, band edge bending, and Coulomb interaction work synergistically to drive the recombination of relatively useless electrons and holes in the hybrid. As a result, the residual electrons and holes, which possess enhanced reducibility and oxidizability, endow the composite with exceptional redox capability. This research can not only deepen our comprehension of designing and fabricating innovative Z-scheme heterojunction photocatalysts but also presents an effective approach to tackle environmental pollution issues in the future.

Chemistry doi: 10.3390/chemistry8050055

Authors: Rongping Wu Dongping Qiu Yogini S. Jaiswal Xinrong Xie Leonard L. Williams Yu Fan Hedong Bian Yifu Guan Shaoyang Su

Cyclodepsipeptides constitute a structurally diverse class of natural products composed of amino acid and hydroxy acid residues interconnected through both amide and ester bonds. Among them, xylaroamide A, a cyclic heptadepsipeptide, was recently identified from an endolichenic Xylaria species via a molecular networking-guided discovery approach. Despite xylaroamide A exhibiting intriguing structural features and notable bioactivity potential, its total synthesis has thus far remained unexplored. Herein, we report the first total synthesis of xylaroamide A, achieved through a hybrid solid/solution-phase synthetic approach. The linear precursor was assembled in accordance with the native amino acid sequence via Fmoc-based solid-phase peptide synthesis, incorporating the preassembled ester fragment at a later stage of assembly. Subsequent macrocyclization took place under high-dilution conditions to furnish the target cyclodepsipeptide. The structure of the synthetic product was confirmed by means of optical rotation and NMR and MS spectroscopic analyses, which exhibited good agreement with the reported data for the natural product. This work establishes a reliable and efficient synthetic route to xylaroamide A and provides a foundation for further bioactivity and structure optimization investigations.

Chemistry doi: 10.3390/chemistry8040054

Authors: Lvming Zhu Yarong Wang Yang Li

In recent years, antiaromatic compounds have gained significant attention in optoelectronic materials, catalytic synthesis, and biomedicine due to their unique electronic structures and properties, emerging as a research frontier in organic chemistry. Over the past five years, a variety of novel antiaromatic metallacycles have been reported. Their electronic structures, however, differ significantly from those of conventional antiaromatic systems due to the involvement of transition metal d orbitals. In this context, computational methods, particularly density functional theory, play an important role in evaluating and understanding antiaromaticity. This paper reviews representative examples of antiaromatic metallacycles reported in the past five years, with particular emphasis on the critical role of computational chemistry methods in characterizing their antiaromatic nature, aiming to provide valuable insights for future research in this rapidly evolving area.

Chemistry doi: 10.3390/chemistry8040053

Authors: Sara Rached Khaoula Mzioud Malak Rehioui Mohamed Khattabi Hamada Imtara Otmane Kharbouch Mohammed Er-rajy Amar Habsaoui Mohamed Ebn Touhami Fuad Al-Rimawi

This study investigates the antioxidant and anticorrosive properties of Mentha pulegium L. essential oil (MP EO) as a sustainable and eco-friendly alternative to synthetic oxidation inhibitors. The antioxidant activity of MP EO was evaluated using the ferric reducing antioxidant power (FRAP) assay, which demonstrated a strong electron-donating capacity and effective reduction of ferric ions, indicating promising antioxidant potential. The anticorrosive performance was assessed on mild steel in 0.5 M H2SO4 using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed inhibition efficiencies of up to 75.8% at a concentration of 2 g/L. Molecular docking simulations revealed favorable binding interactions between the key oil components (pulegone and menthone) and the ROS-generating enzyme model (PDB ID: 2CDU), providing complementary mechanistic insight into their potential role in oxidative stress modulation. Additionally, quantum chemical calculations highlighted electronic properties favoring adsorption on metallic surfaces. Surface morphology analysis using SEM/EDX confirmed the formation of a protective film on steel in the presence of MP EO. These combined findings position Mentha pulegium essential oil as a potent, biodegradable candidate for both antioxidant applications and corrosion prevention in acidic environments.

Chemistry doi: 10.3390/chemistry8040052

Authors: Yihan Yu Mei Yang

Chitosan is non-toxic, harmless, biocompatible, and antimicrobial, and can be readily modified. These properties have made it widely used in carrier research. Based on this, a fluorescent probe P was synthesized in high yield from naphthalimide derivatives and carboxymethyl chitosan (CMCS). The probe exhibited enhanced fluorescence in the presence of Al3+ and quenched fluorescence in the presence of Mg2+ in different media. Among common metal ions and anions, the probe demonstrated good selectivity and sensitivity toward Al3+ and Mg2+. Under optimal conditions (ethanol–water solution, 1:9, v:v, pH 6.0, 20 mM HEPES), a significant linear relationship was observed for Al3+ in the concentration range of 0–90 µM. In ethanol, the fluorescence intensity of the probe at 427 nm decreased regularly with increasing Mg2+ concentration, also showing a clear linear relationship within the 5–90 µM range.

Chemistry doi: 10.3390/chemistry8040051

Authors: Oscar Antonio Escobar Juárez Ebelia Del Angel Meraz Enrique Quiroga González Mayara Osorio García José Guadalupe Pacheco Sosa Mayra Agustina Pantoja Castro María Guadalupe Hernández Cruz

Biochars derived from post-consumer coffee residues were synthesized using NaCl and NaHCO3 as impregnation agents, which were pyrolyzed at 500 and 1000 °C. Structural characterization revealed that NaHCO3 treatment at 1000 °C generated a highly interconnected porous network, with a surface area of 1353.22 m2 g−1, pore volume of 0.83 cm3 g−1, and average pore size of 2.6 nm. These features, confirmed by nitrogen physisorption and SEM, favor Na+ accessibility and insertion. XRD and Raman analyses indicated a predominantly amorphous carbon, with graphitic domains and an interplanar distance of ≈0.34 nm, providing both adsorption capacity and electrical conductivity. Electrochemical evaluation showed that BCNaHCO3-1000°C achieved an initial capacity of 34 mAh g−1, stable for more than 15 cycles, outperforming NaCl-treated biochars. However, despite the favorable morphology, the high surface area may also promote side reactions and irreversible capacity loss, limiting overall efficiency. These findings demonstrate the feasibility of valorizing coffee waste into carbonaceous materials for sodium-ion battery anodes, while highlighting the need for further optimization of porosity, graphitization, and compositional modifications to enhance energy storage performance.

Chemistry doi: 10.3390/chemistry8040050

Authors: Aijuan Zhang Xinwei Chang Tingting Liu Jiayi An Xin Liu Yike Cui Keqi Li Xianrui Dong

The detection of sulfur hexafluoride (SF6) decomposition products is critical for diagnosing insulation faults in gas-insulated switchgear (GIS). In this study, a vanadium-doping strategy was incorporated into the graphene/MoS2 (GM) heterojunction to design a vanadium-doped graphene/MoS2 (GMV) heterojunction material. Leveraging first-principles density functional theory (DFT), the adsorption behaviors of five characteristic SF6 and its decomposition gases (H2S, SO2, SOF2, SO2F2) on intrinsic GM and GMV were systematically investigated to evaluate their potential for gas sensing applications. Computational results reveal that intrinsic GM exhibits only weak physical adsorption toward all target molecules, with low adsorption energies and negligible charge transfer, which fails to meet practical application requirements. In contrast, GMV demonstrates significantly enhanced adsorption energies for H2S, SO2, and SOF2 at vanadium sites (with a maximum value of −0.388 eV for SO2) and shorter adsorption distances, while SO2F2 and SF6 preferentially adsorb near electron-deficient carbon regions. Intrinsic GMV displays semimetallic properties, with a Fermi level at 0.126 eV and a band gap of 0.0017 eV. Upon adsorption of H2S, SOF2, SO2F2, or SF6, the Fermi level undergoes a moderate shift (ranging from −1.083 eV to +0.349 eV), with minimal changes in the band gap. Conversely, SO2 adsorption induces a substantial downward shift of the Fermi level to −1.732 eV, accompanied by the emergence of a sharp partial density of states (PDOS) peak near the Fermi level (0–1.5 eV), indicating strong orbital coupling and significant charge transfer. Furthermore, recovery times calculated using classical formulas show that at room temperature and a frequency of 1 × 106 Hz, the recovery time of GMV for SO2 is 2.43 s, outperforming the other four gases and satisfying practical gas sensing requirements. Through comprehensive analysis of adsorption distances, electronic structure changes, and recovery times, GMV exhibits higher selectivity toward SO2. Thus, GMV can serve as a sensing material for detecting GIS insulation faults associated with elevated SO2 concentrations, offering a viable strategy for advancing online monitoring technologies in power systems.

Chemistry doi: 10.3390/chemistry8040049

Authors: Yu Fan Qi Gao Yogini S. Jaiswal Xinrong Xie Rongping Wu Sen Mo Dengsong Zheng Hedong Bian Yifu Guan Leonard L. Williams

Pyrrolo[2,3-d]pyrimidine is a privileged fused heterocyclic scaffold that has attracted considerable attention in medicinal chemistry due to its diverse biological activities. Herein, we report an efficient synthesis strategy for the preparation of the pyrrolo[2,3-d]pyrimidine-based natural toyocamycin aglycone and pyrrolo[2,3-d]pyrimidine derivatives. The synthesis of toyocamycin aglycone features a key benzylamine nucleophilic substitution followed by a palladium-catalyzed cyanation reaction. From a key intermediate derived from this route, nineteen new pyrrolo[2,3-d]pyrimidine derivatives were rapidly synthesized via key Suzuki–Miyaura coupling and amine nucleophilic substitution reactions. Their cytotoxic activities were evaluated against Huh-7 and HepG liver cancer cell lines. Most derivatives were inactive after 24 h. However, 28a–28c, 28e and 28f exhibited moderate cytotoxicity with IC50 values ranging from 5.7 to 62.6 μM. Among them, compound 28e displayed the highest potency against HepG cells, with IC50 values of 5.7 μM. Compared with normal HEK293 cells, it showed a selectivity index (SI) of 3.60 against HepG cells. Preliminary structure-activity relationship analysis suggested that incorporation of a cyclopropyl group further improves antitumor activity.

Chemistry doi: 10.3390/chemistry8040048

Authors: Sibtain Ahmed Mudassir Bashir Hina Andaleeb Shoaib Ahmad Muhammad Bilal Iqbal Rehmani Ahmad Wakeel

Fungal extracts have garnered considerable attention in recent years due to their diverse pharmaceutical potential. The present study investigates the secondary metabolite profile and biological activities of Alternaria citri, a fungal strain associated with citrus fruits. Metabolites were extracted from A. citri grown in Potato Dextrose Broth (PDB) using ethyl acetate and subsequently evaluated for antimicrobial, antioxidant, and cytotoxic activities, alongside gas chromatography–mass spectrometry (GC–MS) profiling. GC–MS analysis identified 14 bioactive compounds in the fungal extract. The extract exhibited antimicrobial activity against Aspergillus flavus, Trichoderma hamatum, Staphylococcus aureus, and Escherichia coli. Moderate total phenolic and flavonoid contents were observed, which correlated with concentration-dependent antioxidant activity as determined by the DPPH assay. Cytotoxic evaluation using NIH/3T3 cells demonstrated potential anticancer activity, with an IC50 value of 126.63 µg/mL. A. citri is an interesting source of bioactive metabolites with potential therapeutic applications. These findings further strengthen the evidence that Alternaria species can serve as promising sources of natural antioxidants and antimicrobials, thereby supporting their potential applications in pharmaceutical and biomedical formulations. This study expands current knowledge of fungal metabolite diversity and establishes A. citri as a potential source of novel therapeutic agents.

Chemistry doi: 10.3390/chemistry8040047

Authors: Ahmed El-Hussein Alexandra Ioanid Adel A. Surour Mahmoud M. Ashry M. N. Sanad Mohamed Farouz Mohamed M. Elfaham M. S. Abd El-Sadek

Magnetic biochar (MBC), a magnetically responsive soil amendment, has attracted considerable attention due to its efficient magnetic separation capability and strong potential for remediating heavy metal-contaminated soils. Despite extensive research, a comprehensive evaluation of its raw materials, synthesis routes, performance-influencing factors, removal mechanisms, and microbial interactions remains limited. This review systematically examines biomass feedstocks and magnetic precursors used in MBC production and critically evaluates preparation methods, including hydrothermal carbonization, co-precipitation, ball milling, microwave pyrolysis, and impregnation–pyrolysis. Key factors affecting heavy metal removal—such as metal speciation, pyrolysis temperature, soil properties, dosage, and feedstock type—are discussed in detail. The primary immobilization mechanisms, including redox reactions, surface and co-precipitation, ion exchange, functional group complexation, physical adsorption, π–π interactions, and electrostatic attraction, are comprehensively analyzed. Furthermore, the interactions between MBC, soil physicochemical parameters, and microbial communities are evaluated to assess ecotoxicological implications. Finally, we provide valuable recommendations for the future direction of magnetic biochar research to advance its application in heavy metal removal from soil.

Chemistry doi: 10.3390/chemistry8040046

Authors: Ahmed Galal Ibrahim

This report investigates the capacity of crystal violet (CV) uptake from aqueous solutions by a sulfonated gel (Sulfo-Gel) made via free radical polymerization of acrylamide and sulfonic monomer (3-Allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt). CV uptake was examined through a batch technique, assessing the effects of various conditions, including uptake time, solution pH, gel dose, initial concentration of dye, and temperature. Results showed that the hydrogel adsorbent removed 74.88% of the CV dye at a gel dose of 500 mg/L in a neutral medium at initial CV concentration of 30 mg/L and contact time 100 min. The adsorption kinetics were best depicted by nonlinear fitting of pseudo-first-order model. Additionally, adsorption isotherms were analyzed using nonlinear fitting of the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models, with the data fitting the Temkin model most effectively. Thermodynamic studies signified the exothermic nature of the adsorption process and its spontaneity.

Chemistry doi: 10.3390/chemistry8040045

Authors: Masahiro Funahashi Shinobu Uemura

Perylene bisimide derivatives are typical n-type semiconductors as well as redox-active materials. However, it has been difficult to produce thin films by solution processes because of their low solubilities in organic solvents. Perylene bisimide derivatives bearing oligosiloxane moieties exhibit columnar phases over wide temperature ranges, including room temperature and high solubilities in organic solvents. The columnar phases are stabilized by nanosegregation between crystal-like one-dimensional π-stacks and liquid-like mantle consisting of oligosiloxane moieties. The electron mobility at room temperature exceeded 0.1 cm2V−1s−1 in the ordered columnar phases of perylene bisimide derivatives bearing four disiloxane chains. Uniaxially aligned thin films of the perylene bisimide derivatives bearing oligosiloxane moieties could be produced by a spin-coating method. The spin-coated films of the perylene bisimide derivatives bearing cyclotetrasiloxane rings could be insolubilized via in situ ring-opening polymerization by the exposure of the thin films to trifluoromethanesulfonic acid vapors. Uniaxially aligned thin films of perylene bisimide derivatives bearing an ethylene oxide chain as well as cyclotetrasiloxane rings could be doped in an aqueous solution of sodium dithionate, resulting in an anisotropic electrical conductivity. Polymerized thin films of perylene bisimide derivatives bearing a crown ether ring exhibited electrochromism in electrolyte solutions. These compounds formed 1:1 complexes with lithium triflate, exhibiting columnar phases at room temperature. The nanostructures of the complexes were stabilized by the electrostatic interaction between cationic crown-metal units and triflate anions.

Chemistry doi: 10.3390/chemistry8040044

Authors: Hugo O. R. P. Malacco Anndréia Letícia Leite Fiusa Maria Clara Hortencio Clemente Gesley Alex Veloso Martins Sílvia Claudia Loureiro Dias José Alves Dias

Emission control of diesel particulate matter (soot) combustion is important for environmental reasons. Catalysts are indispensable for optimizing these processes, as they significantly reduce the combustion temperature. In this work, mixed oxides (cerium–copper, cerium–manganese, and cerium–molybdenum) were prepared by co-precipitation under reasonably similar synthesis conditions, and the effects of their chemical composition on diesel soot combustion were evaluated using the Printex U model particulate. Thermogravimetric analysis (TG/DTG) and temperature-programmed oxidation coupled with mass spectrometry (TPO/MS) were employed for activity characterization. Structural analyses revealed the presence of nanocrystalline phases containing CeO2 (fluorite), CuO (monoclinic), Mn2O3 (cubic), and MoO3 (orthorhombic), depending on the catalyst composition. The most effective catalysts exhibited an equimolar oxide composition (CeO2–MOx). Tests performed at optimized calcination temperatures and with the addition of promoters led to the identification of optimal combustion conditions. The highest activity, corresponding to the lowest combustion temperature, was observed in the following order: CeO2–Mn2O3 > CeO2–CuO > CeO2–MoO3, with values of 382, 409, and 425 °C, respectively, under tight-contact conditions at a Printex U:catalyst ratio of 1:20. With the addition of a 10% Ag2O promoter, the CeO2–Mn2O3 catalyst further reduced the oxidation temperature to 376 °C. Reusability tests generally indicated a 10–20% decrease in catalytic activity by the third reaction cycle.

Chemistry doi: 10.3390/chemistry8040043

Authors: Jin Lin Kaixiang Song Ling Luo Mingkai Zhang Yuexing Zhang

Design and fabrication of high-performance organic semiconductors are still challenging. Here, we designed new D-(A)n type zinc porphyrin end-capped ethynylene-7-(4-hexyl-thiophen-2-yl)-2,1,3-benzothiadiazole (EBTT) oligomers by linking 5,10,15-trisphenyl porphyrin zinc (ZnTPP) with length-variable EBTT oligomers (at the 20-position of porphyrin) [ZnTPP(EBTT)n (n = 1–6)]. The influence of oligomer length on molecular structures, orbital energies, electronic absorption spectra, ionization energies, electronic affinities, and reorganization energies was systematically studied through density functional theory. The charge-carrier mobility of the simulated crystals and the power conversion efficiencies (PCE) using PCBM as the accepter were also predicted. ZnTPP(EBTT)6 show excellent hole/electron mobility of 76.161/9.395 cm2V−1s−1 and extremely high PCE of 25.45%. This work would have significance for the design and synthesis of organic semiconductor materials with large charge-carrier mobility and high PCE performance.

Chemistry doi: 10.3390/chemistry8040042

Authors: Zoltán Köntös Flóra Stedra Viktória Ngo Hang

This study presents a quantitative investigation of substituent effects on the stability of 1:2 complexes formed between para-substituted 2-phenylbenzimidazole ligands and Cu(II) or Co(II) ions. The ligands, featuring hydroxyl (–OH), chloro (–Cl), and nitro (–NO2) substituents, were synthesized via copper acetate-mediated oxidative cyclization. Stability constants (log K) were determined spectrophotometrically using both the Benesi–Hildebrand and Job methods, which yielded perfectly consistent results and confirmed ML2 stoichiometry. For both metal series, the stability decreases in the order –OH > –Cl > –NO2. Excellent linear correlations were obtained between log K and Hammett σ constants, yielding reaction constants of ρ = −0.79 for Cu(II) and ρ = −1.00 for Co(II). These negative ρ values confirm that electron-donating substituents enhance complex stability by increasing electron density on the donor nitrogen. Furthermore, the stability constants for Cu(II) complexes are approximately two orders of magnitude higher than those for Co(II), in agreement with the Irving–Williams series. This work establishes a clear, predictive structure–stability relationship and validates the combined methodological approach for quantifying metal–ligand interactions in tunable benzimidazole systems.

Chemistry doi: 10.3390/chemistry8040041

Authors: Paolo Yammine Nouha Sari-Chmayssem Hanna El-Nakat Darine Chahine Moomen Baroudi Farouk Jaber Ayman Chmayssem

Water pollution is one of the most critical societal and environmental challenges and remains a persisting problem worldwide. The origin of this pollution is diverse, while organic matter occupies a significant portion, originating from different sources. This creates major environmental and health risks, requiring reliable and sensitive analytical tools for effective monitoring. The permanganate index stands as a conventional assessment method for organic pollution, but it demonstrates compound non-specificity toward compounds and limited sensitivity to various contaminant structures. This research introduces cyclic voltammetry as a standalone electrochemical method that provides sensitive detection and characterization of organic oxidizing compounds. Six organic compounds, including gallic acid, phenol, oxalic acid, ascorbic acid, salicylic acid and p-benzoquinone, were used as model compounds and studied in aqueous media. These compounds were analyzed individually, in single-compound mode, to characterize their redox behavior and to identify the voltammetric peaks. Subsequently, a multi-compound analysis was studied to check for the validity of the concept in a more complex matrix. Notably, a strong linear correlation was observed between the measured charge and the theoretical permanganate index, highlighting the quantitative reliability of the electrochemical method. Comparing the obtained results with the permanganate index method confirmed the superiority of cyclic voltammetry in terms of response time and detection capability. The outcomes demonstrate that cyclic voltammetry functions as a robust alternative to the classical chemical oxidation method for environmental water assessment.

Chemistry doi: 10.3390/chemistry8040040

Authors: Nevena Kaličanin Nikolina Popović Kokar Milica Spasojević Savković Anja Stošić Olivera Prodanović Nevena Surudžić Radivoje Prodanović

Imine reductases (IREDs) have emerged as valuable biocatalysts for the asymmetric synthesis of chiral amines, key intermediates in numerous active pharmaceutical ingredients. Their ability to operate under mild reaction conditions with high chemo- and stereoselectivity provides an attractive alternative to conventional metal-catalyzed or chemical reduction processes. However, the broader industrial application of wild-type IREDs is often constrained by their limited substrate scope and moderate catalytic efficiency. Recent advances in biocatalysis have demonstrated that engineered IREDs can catalyze the reduction of a wide range of natural and non-natural imines, significantly expanding their applicability in pharmaceutical and fine chemical synthesis. In parallel, enzyme immobilization strategies have proven highly effective for improving operational stability, facilitating enzyme reuse, and enabling continuous flow biocatalytic processes. Efficient cofactor regeneration systems have further enhanced the practical implementation of IRED-based transformations. Advances in protein engineering, including structure-guided design, semi-rational mutagenesis, and directed evolution, have generated enzyme variants with improved catalytic activity, stereoselectivity, and substrate tolerance. The integration of high-throughput screening technologies and machine-learning-assisted enzyme design has further accelerated the discovery and optimization of efficient IRED biocatalysts. This review summarizes recent progress in the protein engineering and immobilization of IREDs and discusses future perspectives for their industrial application.

Chemistry doi: 10.3390/chemistry8040039

Authors: Na Dong Yiping Pang Shuai Xue Jing Wang Jiancai Leng Chuanfu Cheng Hong Ma

Based on density functional theory, the structural, mechanical, and photoelectric properties of the perovskite material Cs2SeCl6 were systematically studied under pressures ranging from 0 to 50 GPa. Analysis of structural parameters indicates that the lattice constant, unit cell volume, and bond length decrease progressively with increasing pressure. Notably, the material maintains structural stability across the entire pressure range. Electronic property calculations show that Cs2SeCl6 retains an indirect band gap under pressure, with the band gap value monotonically decreasing as pressure increases. The orbital contributions remain almost unchanged at different pressures. The conduction band is mainly composed of Cl-p and Se-p orbitals, while the valence band is dominated by Cl-p orbitals. The analysis of the effective mass indicates that the transport capability of charge carriers is enhanced under compression. Mechanical stability and ductility were evaluated by calculating the elastic constants and derived mechanical moduli, confirming that the material remains mechanically stable under high pressure. Optical properties were investigated by computing the dielectric function, reflectivity, refractive index, optical absorption coefficient, and extinction coefficient. Collectively, the findings of this work demonstrate that the pressurized Cs2SeCl6 exhibits excellent structural robustness, improved charge transport, and promising photoelectric performance, making it a strong candidate for applications in solar cells and other photoelectronic devices.

Chemistry doi: 10.3390/chemistry8040038

Authors: Akiya Ogawa Taichi Tamai Keiko Fujiwara Ryo Tanaka Daichi Kurata Yuki Yamamoto

The reaction mechanism of the gold-catalyzed hydrothiolation of alkenes (1) with thiols (2) has been investigated in detail. The tetranuclear gold complex, (PPh3)4Au4(SPh)2(NTf)2 (A), is a key intermediate in the catalytic hydrothiolation of alkenes. It forms instantaneously when PPh3AuNTf2 and PhSH are mixed in THF. Monitoring the reaction over time using 31P NMR spectroscopy revealed that gold complex A remained stable in the reaction system throughout the hydrothiolation process. In addition, we successfully observed a rapid ligand-exchange reaction between the thiolate group of gold complex A and thiols in solution. The gold-catalyzed alkene hydrothiolation reaction has been applied to the catalytic hydrothiolation of allenes, which have degenerate double bonds. Hydrothiolation of allenes proceeded regioselectively at the terminal double bond. However, the yield was lower than that observed for alkenes, and catalyst deactivation occurred. The hydrothiolation products of allenes were difficult to detach from the gold catalyst, necessitating an increase in the reaction temperature. Since high periodic transition metals such as gold and platinum are effective for hydrothiolation of alkenes and allenes, it is interesting to clarify whether iridium complexes, which belong to the same period as gold and platinum, could also catalyze alkene hydrothiolation. Through a detailed investigation of iridium ligands and reaction conditions, it was found that, in iridium systems, disulfide formation via oxidative coupling of thiols occurs preferentially over hydrothiolation reactions. This is likely due to steric hindrance around the iridium center, which inhibits alkene coordination to the iridium. Additionally, the hydrothiolation proceeding at low yields is believed to be a radical reaction involving electron transfer through the iridium complex.

Chemistry doi: 10.3390/chemistry8030037

Authors: Nikola Maraković

Organophosphorus (OP) nerve agents inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) by phosphylating the catalytic serine. Oxime reactivators can restore enzymatic activity by a nucleophilic attack of the oximate anion on the phosphorus center of the enzyme–OP conjugate; however, clinically used oximes show agent- and enzyme-dependent performance and are particularly challenged by A-series compounds. Here, an in silico strategy is presented to identify candidate antidotes for OP poisoning, including A-series agents. Pharmacophore models are generated from benchmark/template oximes. Pharmacophore-based virtual screening is used to retrieve hit-like scaffolds from the available chemical space, after which selected hits are converted into oxime analogs. Template oximes and newly designed oximes are then docked into the active site of AChE or BChE inhibited by specific nerve agents. The predicted reactivation potential is assessed using mechanistically motivated geometric criteria derived from the accepted reactivation hypothesis, including the distance between the oximate oxygen and the phosphyl phosphorus and the attack angle, relative to the catalytic serine Oγ. This workflow enables a controlled, pairwise comparison of new oximes against their corresponding template oximes for each enzyme–agent combination, providing a rational basis for prioritizing candidates for synthesis and experimental validation. Using the described workflow, we identified a hit compound with the potential to act as an antidote against A-series nerve agent A-230 poisoning.

Chemistry doi: 10.3390/chemistry8030036

Authors: Xiujin Chen Jingyang Jiang Xiufang Huang Chifang Peng

In this work, a ratiometric fluorescent method for carbaryl detection is reported. We found that the combination of rapid hydrolysis of carbaryl and cetyltrimethylammonium bromide (CTAB) emulsification could significantly enhance the intrinsic weak blue fluorescence of carbaryl. By using red fluorescent glutathione-gold nanoculsters (GSH-Au NCs) as a reference signal, ratiometric detection of carbaryl within 3 min was successfully achieved. The method exhibited high sensitivity, with a linear response to carbaryl in the range from 1.0 to 70 ng/mL and an LOD of 0.05 ng/mL. The method was applied for detection of carbaryl in apple and cabbage samples, and recovery rates of 90~101% and 93~110%, respectively, were obtained. These results show that the proposed method for carbaryl detection has great potential for application in food sample monitoring.

Chemistry doi: 10.3390/chemistry8030035

Authors: Ivanka Stoycheva Petar Petrov Bilyana Petrova Boyko Tsyntsarski Angelina Kosateva Lyudmila Velkova Nartzislav Petrov Pavlina Dolashka Jugoslav Krstić

Water purification by adsorption of various pollutants using carbon adsorbents with different characteristics has proven to be an effective method that is often used in purification technologies. In this work, a new method for obtaining a carbon adsorbent with a wide pore size and high surface area has been developed, particularly for the adsorption of bacterial cells. The characterization of the porous texture, the chemical nature of the surface, the structure, and the chemical composition of the obtained adsorbent is studied. The study demonstrates that the hierarchical macroporous structure of the macroporous carbon adsorbent (MCA) is highly effective for the physical sequestration of Escherichia coli from aqueous solutions. The high removal efficiency (86.4%) suggests that this material is a promising candidate for water purification and point-of-use filtration systems, where physical immobilization of pathogens is required.

Chemistry doi: 10.3390/chemistry8030034

Authors: Xuejian Qin Taoyuze Lv

Atomic charges are widely used to analyze molecular electronic structure and substituent effects, yet their numerical values and interpretations are inherently dependent on the adopted density partitioning scheme. Here, we adapt the Equivariant Atomic Contribution framework to molecular systems (EAC-qm), enabling prediction of atom-resolved continuous charge densities from which atomic charges are obtained as spatial moments. The predicted densities reproduce reference density functional theory results with high accuracy and preserve global charge conservation. To assess chemical interpretability, we examine charge responses in monosubstituted aromatic systems using Hammett substituent constants as external empirical references. Atomic charges derived from EAC-qm exhibit a strong linear association with Hammett parameters, compared with values obtained from traditional density partitioning approaches applied to the same electronic structures. These correlations indicate that density-derived charges respond systematically to established substituent electronic trends. Beyond scalar charges, atom-resolved dipole moments can be evaluated as first-order moments of the same continuous density representation. Illustrative examples for formaldehyde (H2CO) and formamide (HCONH2) show that local dipole vectors provide directional information about intra-atomic polarization that is not captured by point-charge models. Overall, the results suggest that machine-learned continuous electron densities provide a representation-consistent basis for constructing atom-centered electronic descriptors with chemical interpretability.

Chemistry doi: 10.3390/chemistry8030032

Authors: Andrea Repetto Gianguido Ramis Ilenia Rossetti

The continuous-flow technologies in organic synthesis for the production of active pharmaceutical ingredients (APIs) are nowadays more and more applied. In-silico process design is a powerful tool able to support organic synthesis in the field of scale-up and process development. Process design feasibility and reliability depend on the availability of a well-defined chemical reaction kinetic scheme, information which is usually derived from experimental datasets collected on purpose. The latter approach is time-consuming and demanding in terms of resources. Different possibilities are here proposed to valorize widely available experimental data from explorative works with different approaches, depending on the nature, richness, and structure of the datasets. The kinetic parameters (i.e., reaction order, kinetic constant, and activation energy) of some interesting organic reactions have been approximately estimated by applying different computational methodologies, thanks to built-in experimental databases. The numerical algebra approach dealing with linear and non-linear regression analysis for the kinetic parameters has been initially considered and related to the database information for oseltamivir synthesis. The Bayesian statistic was applied to the ibuprofen case through the application of the Markov Chain Monte Carlo (MCMC) method for reaction order estimation. At last, a Machine Learning (ML) approach has been applied to the Rolipram and Pregabalin case study. The in-house developed T-ReX experimental kinetic constant database was exploited, with application of the k-Nearest neighbor algorithm for classification and regular expression pattern recognition. Advantages and limitations of the three approaches are discussed.

Chemistry doi: 10.3390/chemistry8030033

Authors: Natalia Rodionova Evgenia Nechaeva German Stepanov Anastasia Petrova Sergey Tarasov

As a primary reaction medium, water profoundly influences the kinetics and mechanisms of chemical processes. External physical treatments, such as vibration, can alter the physicochemical properties of water, thereby modifying reaction outcomes. This study aimed to investigate the effect of vibrational iterations (I0–I7) prepared using the “crossing” technology on the kinetics of the oxidation–reduction reaction between methylene blue and ascorbic acid, a standard model for evaluating external influences. Initial characterization revealed that while pH remained stable across all samples, electrical conductivity and dissolved oxygen levels deviated significantly from the control (intact water), with oxygen concentrations measuring either higher or lower than the control. Following the dissolution of methylene blue in these iterations, absorption spectroscopy was used to monitor decolorization kinetics. Different vibrational iterations influenced distinct kinetic parameters, including the rate constant, half-reaction time, and average reaction rate. Depending on the number of processing steps used to prepare the iterations, these parameters exhibited deviations ranging from 3% to 9% compared to the control. This suggests a complex relationship between the aqueous medium’s structural–dynamic properties and the reactants’ supramolecular organization. These findings underscore the potential of vibrational iterations as a tool for modulating chemical reaction kinetics through aqueous medium engineering. Further research is needed to elucidate the underlying mechanisms and expand the applicability of this approach to other systems.

Chemistry doi: 10.3390/chemistry8030031

Authors: Jadwiga Inglot Dorota Bartusik-Aebisher Katarzyna Bania Klaudia Dynarowicz David Aebisher

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality that combines a photosensitizer, light of an appropriate wavelength, and molecular oxygen to generate cytotoxic reactive oxygen species for selective tissue destruction. Over recent decades, PDT has evolved from early porphyrin-based systems to advanced third-generation photosensitizers incorporating nanotechnology, targeting ligands, and activatable designs, significantly improving tumor selectivity, pharmacokinetics, and therapeutic efficacy. This article offers an in-depth look at the fundamental principles of PDT, including the roles of photosensitizers, light delivery systems, and oxygen dynamics, as well as the resulting biological effects such as direct tumor cell death, vascular shutdown, and immune activation. Clinical applications across oncology, dermatology, ophthalmology, and antimicrobial therapy are discussed, highlighting both established and emerging indications. Furthermore, the review critically examines recent advances in machine learning (ML) and deep learning (DL) applied to PDT, including treatment planning, dosimetry optimization, photosensitizer and nanoparticle design, real-time treatment monitoring, and outcome prediction. By integrating physics-based modeling, multimodal imaging, and artificial intelligence-driven approaches, PDT is transitioning toward adaptive, personalized photomedicine. This work outlines current challenges, future research directions, and the translational potential of AI-enabled PDT systems, emphasizing their role in improving precision, reproducibility, and clinical outcomes.

Chemistry doi: 10.3390/chemistry8030030

Authors: Keyujia Zhong Fang Lei Shiqing Dang Hongyang Zhang Ying Shi Haohong Chen

Perovskite quantum dots (PQDs) face significant performance limitations due to surface defects, which are not sufficiently addressed by conventional single-passivation methods. We introduce a dual-passivation strategy that synergistically combines bifunctional ligand 3-(N,N-dimethyloctadecylammonium)-propanesulfonate (SB3-18) treatment with silica coating to simultaneously passivate undercoordinated Pb2+ ions and bromine vacancies in red-emitting CsPb(Br/I)3 PQDs. This approach nearly triples the photoluminescence quantum yield (PLQY, from 23% to 58%). Systematic structural, morphlogical, binding energy, Fermi level and optical analyses confirm effective defect suppression and enhanced exciton luminescence. The dual-passivated sample QDs:SB3-18@SiO2 also exhibit excellent environmental stability, retaining 85% of their initial emission after 30 min in air and exhibiting improved UV resistance. By combining the PQDs with a CGSO:Tb3+ mechanoluminescent phosphor, a composite film is fabricated with bimodal optical response—color-selective photoluminescence under UV excitation and stress-activated green emission upon scratching. This work presents a robust route to high-performance PQDs and demonstrates their potential for advanced anticounterfeiting and smart optical applications.

Chemistry doi: 10.3390/chemistry8020029

Authors: Yanchen Liu Yameng Zheng Amina Tariq Xiaofei Nan Lingbo Qu Jinshuai Song

Background: While machine learning has advanced molecular conformation generation, existing models often suffer from limited generalization and inaccuracies, especially for complex molecular structures. These limitations hinder their reliability in downstream applications. Methods: We proposed a molecular conformation model combined with a molecular graph pre-training module and a diffusion model (PDCG). Feature embeddings are obtained from a pre-trained model and concatenated with the molecular graph information. Fusion features are used for generating conformations in the model. The model was trained and evaluated on the GEOM-QM9 and GEOM-Drugs datasets. Results: PDCG significantly outperforms existing baselines, which shows markedly superior results. Furthermore, in downstream molecular property prediction tasks, conformations generated by PDCG yield results comparable to those derived from DFT-optimized geometries. Conclusions: Our work provides a robust and generalizable model for accurate conformation generation. PDCG offers a reliable tool for downstream computational tasks, such as the virtual screening of functional materials and drug-like molecules.

Chemistry doi: 10.3390/chemistry8020028

Authors: Enaam A. Al-Harthi Ghaida H. Munshi Jamilah M. Al-Ahmari Mohamed S. A. Darwish

Fabrication of magnetic materials via a facile and environmentally favorable process with high self-heating performance is quite favored for biomedical applications. To tackle this challenge, magnetic ferrite nanoparticles were developed through an ultrasonic-assisted coprecipitation process. Magnetite (Fe3O4), magnetite doped with cobalt nanoparticles (Co0.4Fe2.6O4), and magnetite doped with cobalt/zinc nanoparticles (Zn0.15Co0.25Fe2.6O4) were synthesized using ultrasonic-assisted coprecipitation techniques. Specific loss power (SLP) was estimated to optimize the heating influence under varied magnetic fields, coating agents, and dispersing solvents. Magnetite doped with cobalt/zinc nanoparticles demonstrated elevated SLP 110 W/g with preferable hyperthermic performance, where AMF conditions did not surpass the safety border for human exposure. The self-heating performance of magnetite doped with cobalt/zinc nanoparticles increased with increasing strength at a constant frequency. The self-heating performance of magnetite nanoparticles increased with increasing frequency at constant strength. Hence, the prepared magnetite doped with cobalt/zinc nanoparticles by the ultrasonic-assisted coprecipitation process can be appropriate for biomedical applications.

Chemistry doi: 10.3390/chemistry8020027

Authors: Linxiao Xu Yuquan Liu Jiahong Li Hangyao Wu Yuanqi Wang Ze Yuan Ling Cheng Yang Li Huamin Zhou Yang Liu

Use of the morphotropic phase boundary (MPB) is a promising approach to enhance the electrocaloric effect in ferroelectric polymers. This is usually achieved by a composition method, and polymer processing near the MPB to tune electrocaloric response has attracted little attention. Here, the relative stability between disordered 3/1-helix and ordered all-trans conformations is leveraged by uniaxial stretching to improve the electrocaloric effect in relaxor ferroelectric polymers under low electric fields. It is found that the stretching technique enables a considerably more enhanced electrocaloric response in polymer composition near the MPB at room temperature, compared with counterparts corresponding to the relaxor phase. The electrocaloric-induced temperature change is found to be 4.5 K under a low electric field of 50 MV m−1 in stretched relaxor ferroelectric polymers at room temperature, corresponding to a 60% enhancement over pristine counterparts. This result highlights the critical role of polymer processing in optimizing electrocaloric properties, especially near the MPB, and this can be extended to improve other functionalities, such as piezoelectric response, in relaxor ferroelectric polymers.

Chemistry doi: 10.3390/chemistry8020026

Authors: Musa Sh. Adygamov Emil R. Saifullin Timur R. Gimadiev Nikita Yu. Serov

The critical micelle concentration (CMC) is a fundamental physicochemical property of surfactants with significant implications across multiple industries. This paper presents an uncertainty-aware graph neural network (GNN) that integrates molecular structure and temperature to simultaneously predict CMC values and prediction uncertainties. Trained on a curated dataset of 2133 CMC values with temperature annotations, our GNN achieves comparatively similar performance on two external test sets from similar works. The model provides adequately calibrated uncertainty estimates that reliably quantify prediction confidence. This dual-output approach enables reliable CMC prediction with quantifiable confidence intervals, addressing a practical need for safety-critical applications where underestimation of uncertainty could have serious consequences.

Chemistry doi: 10.3390/chemistry8020025

Authors: Guifeng Xiang Xiaolin Tang Chenhui Ma Zeyu Zheng Yifu Zhang Chi Huang

To reveal the core mechanism of copper-based materials in catalyzing ammonium perchlorate (AP) decomposition, three copper-based materials with the simplest structures (Cu, Cu2O and CuO) are selected as research objects. This study systematically investigates their catalytic performances, gaseous product evolution, kinetic laws, and combustion behavior in AP decomposition. The results show that all three materials exhibit excellent catalytic activity, reducing the peak temperature of AP high-temperature decomposition to 325.1 °C, 329.9 °Cand 337.3 °C, respectively, with the catalytic activity order of Cu > Cu2O > CuO. Gaseous product analysis confirms that both temperature and catalyst type jointly regulate product distribution. Kinetic analysis shows that the activation energy of Cu and Cu2O catalytic processes exhibits a three-stage change of “increase-decrease-increase” (related to their own oxidation), while CuO shows a two-stage change, and the kinetic behaviors of the three are consistent in the later stage. Combustion experiments indicate that catalytic activity is positively correlated with combustion efficiency; the Cu-catalyzed system has the shortest combustion duration (383 ms) and the largest flame area. This study proposes the catalytic process of copper-based materials as “initial property regulation-unified active species (CuO) action”, providing theoretical support for the directional design of high-performance copper-based catalysts.

Chemistry doi: 10.3390/chemistry8020024

Authors: Yingying Yi Wenqian Yang Yi Li Wei Liu Yonggang Yang

Vividly colored cholesteric liquid crystal polymer network (CLCN) patterns based on epoxy resin are used in decorative and anti-counterfeiting applications. These films are typically prepared via cationic photopolymerization and post-polymerization to achieve a high cross-linking degree. In this work, the cross-linking degree is controlled by varying the UV irradiation dosage during photopolymerization. Following this, the reflection band of the CLCN film changes after removing non-cross-linked compounds with acetone. Leveraging the low cationic polymerization rate and the chain termination capability of methanol, a structurally colored CLCN film with regionally tailored cross-linking was fabricated. With the treatment of acetone, a colorful pattern was observed. Moreover, upon immersion in methanol, the film swelled, revealing a colorful pattern. After the evaporation of methanol, the pattern disappeared. Consequently, this CLCN film holds significant potential for information encryption applications.

Chemistry doi: 10.3390/chemistry8020023

Authors: Nikita Yu. Serov Khasan R. Khayarov Irina V. Galkina Marina P. Shulaeva Vyacheslav A. Grigorev Timur R. Gimadiev

The search for new antibacterial agents is an important task due to the emergence of resistance to widely used drugs. Bromine-, chlorine-, and nitro-substituted phenyl ring azomethines with long alkyl chains (C12, C14, C16, and C18) were synthesized and characterized using several experimental methods (NMR and IR spectroscopy, elemental analysis, mass spectrometry). Antibacterial and antifungal activity was tested on several cultures; the synthesized compounds show activity at the level of some commercial antiseptics. Lipophilicity (an important descriptor for predicting biological properties) of the experimentally synthesized and isomeric molecules was determined by three different approaches: quantum chemistry, machine learning (GraphormerLogP model), and an atom contribution model (RDKit library). The quantum-chemical method can account for any spatial arrangements and can be considered the most accurate of the approaches used, but it requires significant computational time. The atom contribution model is the fastest of the methods used, but it gives underestimated results, and different isomers have exactly the same values, in contrast to the quantum chemistry results. Machine learning-based methods (GraphormerLogP) demonstrate acceptable accuracy, sensitivity to isomerism, and orders-of-magnitude higher throughput, making them an optimal tool for high-throughput screening.

Chemistry doi: 10.3390/chemistry8020022

Authors: Oscar Enrique Catalan-Montiel Ana Karen Galvez-Larios Isai Rosales-Cadena América María Ramirez-Arteaga Roy Lopez-Cecenes Jesus Porcayo-Calderon José Gonzalo Gonzalez-Rodriguez

In this study, the corrosion behavior of pure aluminum in methyl esters with different degrees of unsaturation and chain lengths, as found in biodiesel, was investigated using electrochemical techniques. The methyl esters evaluated included methyl acrylate (C4H6O2) and methyl linoleate (C19H34O2), which were added to methyl propionate (C4H8O2) and methyl oleate (C19H36O2), respectively. The electrochemical techniques employed were electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), complemented by detailed scanning electron microscopy (SEM) analyses. The results indicated that both the corrosion rate and the susceptibility to localized corrosion, such as pitting, increased with higher degrees of unsaturation and longer alkyl chain lengths. The corrosion process remained under charge transfer control and was not directly influenced by these factors. However, the charge transfer resistance decreased with increasing unsaturation and chain length, consistent with the observed increase in corrosion rate.

Chemistry doi: 10.3390/chemistry8020021

Authors: Anastasia P. Bebyakina Zeai Huang Olga D. Bochkova Alexey S. Stepanov Irek R. Nizameev Kirill V. Kholin Rustem R. Zairov Ying Zhou Asiya R. Mustafina

The inadequate biosafety of MRI contrast agents (CAs) remains a challenging issue. Both increasing the magnetic relaxivity of CAs and targeting them through conjugation with folates are promising approaches to addressing this issue. Silica nanoparticles (SNs) with Mn2+ ions specifically localized in the outer layer were selected as the target for further surface modification for the covalent attachment of folates. It was shown that when Mn-containing SNs are conjugated with folates via preliminary amino modification of the surface silanol groups, the folate-conjugated SNs suffer from colloidal instability. Thus, precoating Mn-containing SNs with unfolded BSA exposes surface amino groups that successfully conjugate with folates without loss of colloidal stability. Partial washout of surface-localized Mn2+ follows folate conjugation of Mn-containing SNs, although residual Mn2+ ions provide r1(2) relaxivities of 62.1 (160.4) mM−1s−1 at 0.47 T.

Chemistry doi: 10.3390/chemistry8020020

Authors: Diana V. Shuingalieva Damir D. Karachev Ksenia V. Skokova Ivan M. Prosvetov Dmitri I. Fomenkov Vera A. Vil’ Alexander O. Terent’ev

Visible-light photocatalysis enables the integration of classical electrophile/nucleophile chemistry with radical species (free radicals, radical cations, and radical anions) and metallocomplexes, significantly expanding the scope of organic transformations. Substrates capable of generating radicals via single-electron transfer (SET) are therefore of high value in this field. Among conventional radical precursors, organic peroxides occupy a distinctive position due to their unique reactivity. They can generate both oxygen-centered and carbon-centered radicals through either oxidative or reductive SET pathways. Furthermore, organic peroxides can act as radical precursors, nucleophiles, and oxidants. The review emphasizes the advancements of visible-light-mediated reactions utilizing the broad potential of organic peroxides for constructing various chemical bonds.

Chemistry doi: 10.3390/chemistry8020019

Authors: Amit Sarker Mohammad Eanamul Haque Nizam Mainul Morshed Manoj Kanti Datta Huiyu Jiang Fiaz Hussain Imran Ahmad Khan Asfandyar Khan Kashif Javed

Natural plant-based resources are rich in bioactive compounds that offer promising alternatives for developing sustainable, functional textiles. This study focuses on the extraction and application of natural dyes from Gardenia jasminoides as an eco-friendly substitute for conventional synthetic dyes. The dye was extracted using methanol–water (50:50) and ethanol–water (50:50) solvent systems, alongside conventional aqueous extraction, followed by characterization through column chromatography. The characterization of the extracted powders confirmed the presence of gardenia yellow pigments with strong coloration potential. Among the tested extraction methods, ultrasonic-assisted methanol–water extraction (M.W.U.) exhibited the highest dye yield of 29.5%, followed by ethanol–water ultra-sound extraction (E.W.U.) at 24.9%, water ultrasound extraction (W.U.) at 18.35%, and the lowest yield obtained from the water-heater method (W.H.) at 18.25%. The dyed cotton fabrics were tested for color strength (K/S), CIELAB, colorfastness (washing, light, rubbing), and functional properties (antibacterial and vector protection) according to standard operating procedures. The results revealed that an optimal mordant concentration produced the maximum color strength (K/S = 1.7730), with good rubbing (4–5), washing (4–5), and light fastness (5). The dyed fabrics also exhibited excellent antibacterial activity against both Staphylococcus aureus and Escherichia coli, as evaluated by the AATCC 100 test method. For instance, the vector protection property of the cotton dyed fabrics was also excellent, as confirmed by the cage test. Overall, the use of Gardenia jasminoides seed-based natural dye demonstrates not only desirable coloration and functional performance but also significant ecological advantages, reducing chemical pollution and supporting the transition toward environmentally sustainable textile processing.

Chemistry doi: 10.3390/chemistry8020018

Authors: Bo Yang Xiang Yang Minghong Long Yanzhi Yang Xuechun Xiao

Porous Cu/Cu2O catalytic materials with a unique pore structure were successfully synthesized via a one-step solvothermal method using Cu-MOF-74 as the intermediate, followed by induced collapse and oxidation. The structural properties and catalytic performance of the as-prepared Cu/Cu2O materials in the thermal decomposition of ammonium perchlorate (AP) were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis, and thermogravimetry–differential scanning calorimetry (TG-DSC) combined with in situ thermogravimetry–mass spectrometry (TG-MS). The results show that the specific surface area of the Cu/Cu2O material is 46.6697 m2/g, and the average pore diameter is 9.4608 nm. Owing to the synergistic effect of Cu0/Cu+ dual sites on promoting electron transfer during AP thermal decomposition, the Cu/Cu2O catalyst exhibits excellent catalytic activity. Specifically, at a heating rate of 20 °C/min, the addition of 2 wt% Cu/Cu2O reduces the high-temperature decomposition temperature of AP from 473.1 °C to 321.1 °C (a decrease of 151.0 °C), lowers the thermal decomposition activation energy from 296.63 kJ/mol to 253.21 kJ/mol (a reduction of 43.42 kJ/mol), and increases the heat release by 617.8 J/g compared to pure AP. TG-MS analysis revealed that Cu/Cu2O accelerates the decomposition of AP by adsorbing and activating NH3 and HClO4 generated in the low-temperature decomposition stage, facilitating the formation of reactive intermediates such as ClOₓ and promoting the oxidation of nitrogen-containing species. This study demonstrates that the porous Cu/Cu2O material synthesized by the one-step solvothermal method is a promising catalyst for enhancing the thermal decomposition performance of AP in solid propellants.

Chemistry doi: 10.3390/chemistry8020017

Authors: Ashok Madarakhandi Sujeet Kumar Nishith Teraiya Gokulakrishnan Sakthivel Basavaraj Metikurki Veda B. Hacholli Dominique Schols Febina Ravindran Bibha Choudhary Subhas S. Karki

Glycogen synthase kinase-3 beta (GSK-3β) is a multifunctional serine/threonine kinase mediating multiple cellular functions, such as differentiation, apoptosis, and cell proliferation. Because of their ability to alter carcinogenic pathways, GSK-3β inhibitors are being explored for the development of anticancer molecules. In the present study, we synthesized and evaluated the cytotoxic properties of a series of twenty indole–triazole-linked pyrazolone derivatives, 10Aa–Ed. All derivatives were characterized by FTIR, 1H/13C NMR, and high-resolution mass spectrometry (HRMS) methods. All compounds and standards, sunitinib and 5-Fluorouracil (5-FU), were screened against four adherent cell lines, including pancreatic adenocarcinoma (Capan-1), colorectal carcinoma (HCT-116), glioblastoma(LN229), and lung carcinoma (NCI-4460), and four non-adherent cell lines, including acute myeloid leukemia (HL-60), chronic myeloid leukemia (K562), T lymphoblast (MOLT4), and non-Hodgkin lymphoma (Z138). Among the screened derivatives, molecule 10Aa showed cytotoxicity against MOLT 4, Z138, and HL60 with CC50 values of 14.45 μM, 15.34 μM, and 17.56 μM, respectively. GSK-3β kinase inhibition was evaluated with the 10Aa, which is capable of inhibiting GSK-3β in a dose-dependent manner. Additionally, molecular docking was performed to estimate the correlation between invitro data and GSK-3β binding affinity. The outcomes of the invitro experiments demonstrated strong concordance with the insilico data. The discovery yielded compounds 10Aa and 10Cd, which can be modified to create effective anticancer agents that target GSK-3β.

Chemistry doi: 10.3390/chemistry8020016

Authors: Chaoyang He Tingting Jiang Langbo Yi Wenyong Hu

To address the challenge of removing copper from copper–ammonia complex wastewater in the printed circuit board (PCB) industry, this study employed natural chitosan (CTS) as the base material. Dithiocarbamate (DTC) groups were grafted onto CTS, followed by further carboxylation (-COOH) to produce two novel adsorbents: DTC-CTS and DTC-CTS-COOH. The materials were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), SEM, and related techniques. The effects of solution pH, adsorption isotherms, kinetics, and regeneration performance were systematically investigated. Characterization results confirmed the successful introduction of DTC and carboxyl (-COOH) groups. Adsorption experiments demonstrated that DTC-CTS-COOH exhibited superior Cu2+ adsorption performance across pH 5–8, achieving a removal efficiency of (97.67 ± 1.3)% at pH 7. Its adsorption behavior followed the Langmuir model, with a maximum adsorption capacity (Qm) of 234.8 mg·g−1 at 318.15 K, significantly higher than that of DTC-CTS (183.6 mg·g−1). Adsorption kinetics conformed to a pseudo-second-order model, indicating rapid adsorption rates. After five adsorption-desorption cycles, DTC-CTS-COOH maintained a Cu2+ removal rate above 68.41%. The synergistic interaction between -COOH and DTC functional groups enhanced the adsorbent’s capacity, rate, and pH adaptability, demonstrating that DTC-CTS-COOH holds strong potential for application in the treatment of complex copper–ammonia wastewater.

Chemistry doi: 10.3390/chemistry8020015

Authors: Thiago de Souza Dias Silva Afonso Santine M. M. Velez Tiago Ribeiro Rodriguez João Vitor da Costa Silva Henrique Previtalli-Silva Flávia de Oliveira Cardoso Célio Geraldo Freire-de-Lima Otávio Augusto Chaves Debora Decote-Ricardo Marco Edilson Freire de Lima

This work reports the synthesis and characterization of a new molecular hybrid 4, created by combining 1,4-naphthoquinone with the drug zidovudine (AZT) through an azide-alkyne cycloaddition reaction catalyzed by Cu1+. In vitro studies assessed the anti-trypanosomatid activity of hybrid 4, along with its precursors and synthetic intermediates (1, 2, and 3), against Trypanosoma cruzi (T. cruzi Tulahuen C2C4 LacZ), Trypanosoma brucei (T. b. brucei 427), and Leishmania infantum, as well as cytotoxicity in RAW 264.7 macrophages and LLC-MK2 cells. The biological results confirm the molecular design, showing that the new hybrid is effective against both epimastigotes and amastigotes of T. cruzi (IC50 = 22.26 ± 5.78 μM and 143.10 ± 5.79 μM, respectively), with approximately 4.5-fold better capacity than AZT to inhibit the epimastigote form. Additionally, the hybrid was also active against bloodstream T. b. brucei (IC50 = 54.47 ± 6.70 μM), with approximately 2.2-fold better capacity than AZT to inhibit this parasite. It also shows low toxicity in RAW 264.7 macrophages (CC50 > 200 μM) and LLC-MK2 cells (CC50 > 200 μM). For example, hybrid 4 exhibited approximately a 6.6-fold higher SI than 1,4-naphthoquinone 1 against T. cruzi amastigotes. In this context, the work contributes to the broader knowledge base guiding the design of hybrid molecules for antiparasitic chemotherapy. It provides a rational foundation for preparing subsequent, more potent analogues.

Chemistry doi: 10.3390/chemistry8020014

Authors: Xianyu Meng Ying Wang Jie Li Hongxing Wang Chenglong Yu Jia Guo Zhuo Zhang Qingli Qian Buxing Han

The catalytic hydrogenation of carbon dioxide (CO2) represents a transformative approach for reducing greenhouse gas emissions while producing sustainable fuels and chemicals, with ethanol being particularly promising due to its compatibility with existing energy infrastructure. Despite significant progress in converting CO2 to C1 products (e.g., methane, methanol), selective synthesis of C2+ compounds like ethanol remains challenging because of competing reaction pathways and byproduct formation. Recent advances in thermo-catalytic CO2 hydrogenation have explored diverse catalyst systems including noble metals (Rh, Pd, Au, Ir, Pt) and non-noble metals (Co, Cu, Fe), supported on zeolites, metal oxides, perovskites, silica, metal–organic frameworks, and carbon-based materials. These studies reveal that catalytic performance hinges on the synergistic effects of multimetallic sites, tailored support properties and controlled reaction micro-environments to optimize CO2 activation, controlled hydrogenation and C−C coupling. Mechanistic insights highlight the critical balance between CO2 reduction steps and selective C−C bond formation, supported by thermodynamic analysis, advanced characterization techniques and theoretical calculations. However, challenges persist, such as low ethanol yields and undesired byproducts, necessitating innovative catalyst designs and optimized reactor configurations. Future efforts must integrate computational modeling, in situ/operando studies, and renewable hydrogen sources to advance scalable and economically viable processes. This review consolidates key findings, proposes potential reaction mechanisms, and outlines strategies for designing high-efficiency catalysts, ultimately providing reference for industrial application of CO2-to-ethanol technologies.

Chemistry doi: 10.3390/chemistry8020013

Authors: Erick Nazareno García-Intriago Dimas Alberto Pincay-Pilay Mercedes Marcela Pincay-Pilay Carlos Augusto Morales-Paredes María Celina Santos-Fálconez Jorge Gabriel Palacios-Revelo Iris B. Pérez-Almeida Carlos Alfredo Cedeño-Palacios

Cocoa (Theobroma cacao L.) is an important source of bioactive compounds with high antioxidant capacity and antimicrobial properties. However, these compounds are susceptible to degradation by light, oxygen, pH, and temperature, which limits their functionality. This study evaluated the microencapsulation of CCN-51 cocoa extracts by spray drying, using maltodextrin (MD) and gum arabic (GA) as encapsulating agents, with the aim of preserving their bioactive activity and promoting their application in food. Microcapsules formulated with 5%GA showed the highest encapsulation efficiency (77.5%) and the highest phenolic content (92.7 GAE/g), showing significant differences compared to formulations with MD (p < 0.0001). Antioxidant capacity, quantified using the ABTS method, reached 583.3 µmol TE/g for 5% GA, significantly exceeding that of microcapsules with 10%MD (230.9 µmol TE/g; p < 0.0001). In terms of antimicrobial activity, microcapsules containing 5%MD showed greater inhibition against Escherichia coli (22.1 mm) and Staphylococcus aureus (12.3 mm), while those containing GA recorded halos of 10.1 mm and 12.1 mm. When applied to chicken muscle, treatments with 5%GA significantly reduced microbial growth for 72 h, demonstrating that the prepared microcapsules have high bioactivity, stability, and antimicrobial capacity in samples of meat products that are widely consumed and potentially susceptible to spoilage due to microbial growth.

Chemistry doi: 10.3390/chemistry8020012

Authors: Susanta Mandal Tushar Sharma Banstola Dhan Maya Chettri Kimron Protim Phukan Biswajit Gopal Roy

Alkyl-substituted pyridines are ubiquitous structural motifs found in natural products, pharmaceuticals, agrochemicals, and functional organic materials. However, their direct synthesis remains challenging because of the electron-deficient nature of the pyridine ring and the harsh conditions typically required for conventional carbonyl-to-alkane reduction. Herein, we report a mild and environmentally benign Pd/C–H2 catalytic system that enables one-pot oxidative aromatization–deoxygenation of dihydropyridinedione derivatives to afford alkyl-substituted pyridines. The transformation proceeds efficiently at room temperature under atmospheric hydrogen pressure using ethanol as a green solvent, delivering the desired products in up to 91% isolated yield. The protocol exhibits broad substrate scope, high chemoselectivity, operational simplicity, and excellent catalyst recyclability. Mechanistic studies, including hydrogen-free control experiments and intermediate isolation, support a sequential Pd-mediated pathway involving oxidative aromatization, stepwise hydrogen-transfer reduction, and final deoxygenation, with water as the sole stoichiometric by-product. This method provides a sustainable and scalable alternative to classical harsh or reagent-intensive deoxygenation strategies for the synthesis of alkyl-substituted pyridines.

Chemistry doi: 10.3390/chemistry8010011

Authors: Aikun Liu Xu Liu Zixuan Huang Yanqing Ge

Nitrite, as a widely present nitrogen oxide compound in nature, and is extensively distributed in production and daily life; precise and rapid detection of it is of great significance for ensuring human health. This study developed nitrogen-doped carbon dots (N-CDs) using malic acid and 3-diethylaminophenol as precursors by one-step hydrothermal treatment. The obtained N-CDs exhibited strong green fluorescence with a high quantum yield of 20.86%. More importantly, they served as a highly effective fluorescent probe for NO2− sensing, demonstrating a low detection limit of 28.33 μM and a wide linear response range of 400 to 1000 μM. The sensing mechanism was attributed to an electrostatic interaction-enhanced dynamic quenching process. Notably, the probe enabled dual-mode detection: a distinct color change from light pink to dark brown under daylight for visual semi-quantification, and quantitative fluorescence quenching. The N-CDs showed excellent selectivity over common interfering ions. Furthermore, their low cytotoxicity and good biocompatibility allowed for successful bioimaging of exogenous and endogenous NO2− fluctuations in live HeLa cells. This work presents a facile green strategy to synthesize multifunctional N-CDs that realized the sensitive, selective, and visual detection of NO2− in environmental and biological systems.

Chemistry doi: 10.3390/chemistry8010010

Authors: Fernando Rodríguez

A recent theoretical study of CsMnF4 under pressure presents conclusions on its structural, optical, and magnetic behavior that conflict with established experimental evidence. Crucially, that work omits key prior experimental results on CsMnF4 and related Mn3+ fluorides under pressure. This commentary examines the resulting discrepancies, arguing that omissions of this data undermine the theoretical estimates and methodological validity. This paper provides a critical overview centered on two main points: the contested nature of the pressure-induced high-spin to low-spin transition observed in CsMnF4 at ~37 GPa, and a detailed discussion of Jahn–Teller physics in this archetypal system. By reconciling the existing literature with the new theoretical claims, this work aims to clarify the high-pressure behavior of CsMnF4. A thorough analysis on the spectroscopic and magnetic properties of Mn3+ fluorides is included to support this commentary.

Chemistry doi: 10.3390/chemistry8010009

Authors: Suresh Sunuwar Carlos E. Manzanares

In this paper, characteristic ultraviolet absorption spectra are presented for benzene and chlorobenzene in transparent hexagonal water–ice solutions at temperatures between 273 K and 78 K. In addition, the liquid solution spectra at 292 K have also been included. The two lowest symmetry-forbidden transitions from the ground state (1A1g) to the first excited level of symmetry (B2u), denoted as 1B2u ← 1A1g, and the transition from the ground state to the second excited level of symmetry (1B1u), denoted as 1B1u ← 1A1g, of benzene are recorded. The two lowest transitions of chlorobenzene from the ground state (1A1) to the first excited level of symmetry (1B2), denoted as 1B2 ← 1A1, and the transition from the ground state to the second excited level of symmetry (1A1) denoted as, 1A1 ← 1A1, are also studied. The bands are obtained for slowly cooled transparent water–ice solutions. Such ice samples, that were frozen from liquid water and cooled, show gradual changes in the spectra. Our study shows the spectra at eight temperatures, separating the spectra in different regions based on the range for the bands from ground state to the first and second excited states of benzene and chlorobenzene, observing changes in the integrated absorbances as a function of the temperature. For the spectra recorded at 78 K, the peak absorbances as a function of the wavelength are presented and tentatively assigned. Peak assignments are based on the known literature of benzene and chlorobenzene. The temperature range of our study covers some of the average temperatures that have been found in the icy moons of Saturn and the polar regions of Earth.

Chemistry doi: 10.3390/chemistry8010008

Authors: Edwin S. Eyube Ibrahim Yusuf John B. Ayuba Ishaya I. Fwangle Bayo Nyangskebrifun Fatima M. Sahabo Abdullahi A. Hamza

A precise characterization of molecular vibrations and thermodynamic properties is essential for applications in spectroscopy, computational modeling, and chemical process design. In this study, the q-deformed Tietz (qDT) oscillator is applied to examine vibrational energy spectra of diatomic molecules and thermodynamic properties of nonlinear symmetric triatomic molecules. Vibrational energy eigenvalues were obtained analytically using the improved Nikiforov-Uvarov method. The symmetric vibrational mode was described with the qDT oscillator, while asymmetric and bending modes were modeled using the rigid rotor harmonic oscillator (RRHO); translational and rotational contributions were incorporated from standard models. For diatomic molecules (BrF, CO+, CrO, ICl, KRb, NaBr), mean absolute percentage errors (MAPE) ranged from 0.53% to 1.73% for vibrational energy eigenvalues and 0.34% to 1.08% for potential fits. Extending the analysis to triatomic molecules, thermodynamic properties of AlCl2, BF2, Cl2O, OF2, O3, and SO2 were calculated with the qDT model, yielding low MAPE benchmarked against NIST-JANAF reference data: entropy 0.203% to 0.614%, enthalpy 1.792% to 5.861%, Gibbs free energy 0.419% to 1.270%, and constant-pressure heat capacity 1.475% to 4.978%. These results demonstrate the versatility and accuracy of the qDT oscillator as an analytical framework connecting molecular potentials, vibrational energies, and thermodynamic functions, providing a practical and tractable approach for modeling both diatomic and symmetric triatomic systems.

Chemistry doi: 10.3390/chemistry8010007

Authors: Miquel Solà Luigi Cavallo

Cyclic π-conjugated organic species are classical examples of (anti)aromatic compounds. Two key features that characterize their (anti)aromatic behavior are the aromatic stabilization (or destabilization) energy and the degree of bond-length equalization or alternation. Both properties depend strongly on the size of the π-conjugated ring. In small rings, systems with 4n + 2 π electrons exhibit substantial aromatic stabilization and pronounced bond-length equalization, whereas those with 4n π electrons show significant antiaromatic destabilization accompanied by clear bond-length alternation. As the ring size increases, however, the differences in aromatic stabilization energy and bond-length patterns become progressively less distinct.

Chemistry doi: 10.3390/chemistry8010006

Authors: Mahfouz Saeed

Among the most promising alloys for photovoltaic applications is copper–indium–gallium–selenide (CIGS) because of its enhanced optical properties. This study examines the influence of current density and pulse timing on the electrodeposition of Cu(In, Ga)Se2 (CIGS) thin films from a dilute electrolyte. It assesses how these parameters affect deposition quality, film characteristics, and device performance. CIGS absorber layers were electrodeposited using a pulsed-current method, with systematic variations in current density and pulse on/off durations in a low-concentration solution. The deposited precursors were subsequently selenized and incorporated into fully assembled CIGS solar cell architectures. Structural characteristics were analyzed by X-ray diffraction (XRD), whereas composition and elemental distribution were assessed by energy-dispersive X-ray spectroscopy (EDS). Optical properties pertinent to photovoltaic performance were evaluated through transmittance and reflectance measurements. The results indicate that moderate current densities, when combined with brief off-times, produce dense, microcrack-free films exhibiting enhanced crystallinity and near-stoichiometric Cu/(In + Ga) and Ga/(In + Ga) ratios, in contrast to films deposited at higher current densities and extended off-times. These optimized pulse parameters also produce absorber layers with advantageous optical band gaps and improved device performance. Overall, the study demonstrates that regulating pulse parameters in attenuated electrolytes is an effective strategy to optimize CIGS film quality and to facilitate the advancement of economical, solution-based fabrication methods for high-performance CIGS solar cells.

Chemistry doi: 10.3390/chemistry8010005

Authors: Yong Gong Yu Putera Danial Izzat Kamaruzaman Shaun Wyrennraj Ganaprakasam Nurul Ain Abu Bakar Eddy Saputra Rohmatul Amin Muhammad Jefri Mohd Yusof

The increasing use of electronic cigarettes (e-cigarettes) highlights the need for accessible and reliable biomarkers to assess nicotine exposure. Fingernails represent a non-invasive and stable keratin matrix capable of capturing the long-term incorporation of xenobiotics such as cotinine, the primary metabolite of nicotine. This study aimed to optimise cotinine extraction from fingernails using Response Surface Methodology (RSM) with a central composite design prior to quantification by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Three extraction variables were evaluated: NaOH concentration, extraction temperature, and extraction time. Numerical optimisation identified the optimal conditions as 3.74 M NaOH, 50 °C, and 40 min, yielding a predicted recovery of 84.06% with a high desirability value of 0.973. The calibration curve demonstrated excellent linearity (R2 = 0.9998), with a limit of detection of 14.5 µg kg−1 and a limit of quantification of 43.8 µg kg−1. The RSM model exhibited strong predictive performance, with an R2 of 0.9990, an adjusted R2 of 0.9982, and a predicted R2 of 0.9958, supported by a non-significant lack of fit and robust residual diagnostics. Application of the optimised protocol to real fingernail samples successfully differentiated e-cigarette smokers from non-smokers based on characteristic cotinine-associated FTIR spectral features and quantitative measurements, demonstrating the practical utility of the proposed method. Overall, this study establishes a rapid, chromatography-free, and cost-effective analytical approach for monitoring long-term nicotine exposure using keratin-based matrices.

Chemistry doi: 10.3390/chemistry8010004

Authors: Maria Antonietta Dettori Davide Fabbri Roberto Dallocchio Nicola Culeddu Maria Orecchioni Paola Carta

This study investigates the synthesis and photochemical behavior of a series of (E)-1-aryl-1,3-butadienes with different aromatic substituents. Despite their simple structure and straightforward preparation, detailed studies of their photochemical properties, especially UV light-induced (E) to (Z) isomerization, are scarce. Our results demonstrate that these compounds can efficiently undergo photo-triggered geometric changes, highlighting their potential as functional units in photochemical applications. The findings underline the significance of extended conjugation in managing excited-state processes, providing new insights into the dynamics of photoinduced transformations in conjugated diene systems. Additional computational analyses show how geometric modifications influence conformational energies in the synthesized compounds. Overall, these results improve understanding of structure–reactivity relationships and lay the foundation for designing photoresponsive materials based on (E) and (Z)-1-aryl-1,3-butadiene frameworks, with promising applications in photochemistry and materials science.

Chemistry doi: 10.3390/chemistry8010003

Authors: Olga I. Logacheva Oleg A. Pimenov George A. Gamov

This paper presents accurate TD-DFT calculations for several mixed-ligand gold(III) complexes with ligands including Cl−, Br−, I−, OH−, and NH3. The calculated results show excellent agreement with available experimental data. The spectral shapes are determined by charge transfer transitions, which are systematically influenced by the ligand’s position in the spectrochemical series. The main vertical electron transitions and the molecular orbitals involved are identified and discussed. Furthermore, the results indicate that the iodide-containing gold(III) complexes, [AuCl2I2]− and [AuI(OH)3]−, are viable candidates for practical synthesis.

Chemistry doi: 10.3390/chemistry8010002

Authors: Vladimir Glebovich Povarov Olga Vladimirovna Cheremisina Daria Artemovna Alferova

This study examines the activity coefficients of benzene, toluene, and di-(2-ethylhexyl)phosphoric acid (D2EHPA) in binary benzene–D2EHPA and toluene–D2EHPA systems, as well as the ternary n-hexane–toluene–D2EHPA system, using gas chromatography at 293.0 K. The primary objective was to determine UNIFAC model interaction parameters and validate their accuracy for predicting thermodynamic behavior in these systems. Experimental measurements revealed activity coefficient maxima for benzene and toluene at mole fractions of 0.8–0.9, decreasing to 0.46–0.67 in dilute solutions. The UNIFAC interaction parameters were calculated as follows: ACH–HPO4 (−334, 4605), ACCH3–HPO4 (680, 467), and refined CH2–HPO4 (54, 1199). The UNIFAC model achieved deviations of less than 2% from experimental data in both binary and ternary systems. A novel methodology incorporating intermediate standards for gas chromatography was developed to overcome challenges in measuring volatile solvent concentrations, enhancing measurement precision. These findings enable accurate prediction of activity coefficients in mixtures of alkanes, cycloalkanes, and monoaromatic hydrocarbons with D2EHPA, offering significant implications for optimizing metal liquid–liquid extraction processes.

Chemistry doi: 10.3390/chemistry8010001

Authors: Nuaman F. Alheety Sameer A. Awad Mustafa A. Alheety Mohanned Y. Darwesh Jalal A. Abbas Rafaâ Besbes

Benzimidazole derivatives are a privileged family of heterocyclic compounds that have remarkable structural diversity and find various pharmacological and industrial applications. In this article, we report on their synthetic procedures, ranging from classic condensation methodologies to modern green chemistry methodologies (microwave-assisted methods and catalyst-free methods). The biological significance of these derivatives is discussed, and their anticancer, antimicrobial, anti-inflammatory, antioxidant, antiparasitic, antiviral, antihypertensive, antidiabetic, and neuroprotective activities are reported. This article also reviews recent industrial applications, with special reference to hydrogen storage and environmental sustainability. The latest computational techniques, such as density functional theory (DFT), molecular docking, and molecular dynamics simulation, are particularly emphasized because they can be instrumental in understanding structure–activity relationships and rational drug design. In summary, the present review describes the importance of new benzimidazole derivatives, which are considered a different class of multitarget agents in medicinal chemistry and computational drug design.

Chemistry doi: 10.3390/chemistry7060203

Authors: Dragana Medić Ivan Đorđević Maja Nujkić Vladan Nedelkovski Aleksandra Papludis Stefan Đorđievski Nataša Gajić

The recycling of spent lithium-ion batteries (LIBs) requires efficient and sustainable methods for recovering critical metals. In this study, the leaching behavior of LiCoO2 cathode material obtained from spent LIBs was investigated in phosphoric acid, using copper powder recovered from waste LIBs as a reducing agent. Leaching experiments were conducted under various conditions (temperature, solid-to-liquid ratio, agitation rate) and compared with systems without copper. In the absence of copper, lithium and cobalt, recoveries after 30 min were approximately 77% and 23%, respectively. The addition of copper significantly enhanced leaching, achieving >96% recovery for both metals at 80 °C, with most extraction occurring within the first 30 min. Kinetic analysis using the shrinking core model indicated a mixed-control mechanism involving both surface chemical reaction and product layer diffusion. The calculated activation energies were 20.2 kJ·mol−1 for lithium and 16.1 kJ·mol−1 for cobalt. Solid residues were characterized by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). XRD results revealed that the composition of the residues varied with leaching temperature: Co3O4 was consistently detected, whereas Cu8(PO3OH)2(PO4)4·7H2O appeared only when leaching was performed above 50 °C. Thermodynamic calculations supported the reductive role of copper and provided insight into possible reaction pathways. These findings confirm the effectiveness of copper-mediated leaching in phosphoric acid and demonstrate that temperature strongly influences residue phase evolution, thereby offering valuable guidance for the design of sustainable LIB recycling processes.

Chemistry doi: 10.3390/chemistry7060202

Authors: Xingzhi Pang Hong Jiang Jianbing Yang Chaolan Zhang Mingjun Pang Rui Chen Jing Li Bin Sun Dongming Yang Lang Su Zhiqi Zhai

This study investigated the efficiency of biochar in eliminating Cd(II) and Pb(II) ions from slurries generated from construction-derived waste materials. The construction waste slurry samples consisted of genuinely contaminated sludge sediments. To improve the adsorption capacity of biochar for metal ions, coconut shell-derived biochar was subjected to hydrochloric acid treatment. The modified biochar demonstrated an improved porous structure and showed a higher concentration of oxygen-containing functional groups compared to the untreated biochar. After a 48 h contact with the contaminated slurry, the treated biochar attained removal efficiencies of 21.15% for Cd(II) and 19.43% for Pb(II). The kinetic study of the adsorption process conformed to a pseudo-second-order model. Density functional theory (DFT) computations clarified the adsorption mechanism of Cd(II) and Pb(II) by carboxyl (-COOH) and hydroxyl (-OH) functional groups. The findings demonstrated that functional groups contribute lone-pair electrons for the adsorption of heavy metal ions. The carboxyl (-COOH) functional group exhibited a greater affinity for binding Cd(II) and Pb(II) ions than the hydroxyl (-OH) group, which explains the improved adsorption efficiency seen in biochar treated with hydrochloric acid. These findings offer theoretical validation for the use of hydrochloric acid-modified biochar as an efficient adsorbent for the remediation of sludge contaminated with Cd(II) and Pb(II).

Chemistry doi: 10.3390/chemistry7060201

Authors: Junhong Li Kaisheng Song Jun Li

Accurate potential energy surfaces (PESs) are the prerequisite for precise studies of molecular dynamics and spectroscopy. The permutationally invariant polynomial neural network (PIP-NN) method has proven highly successful in constructing full-dimensional PESs for gas-phase molecular systems. Building upon over a decade of development, we present CQPES v1.0 (ChongQing Potential Energy Surface), an open-source software package designed to automate and accelerate PES construction. CQPES integrates data preparation, PIP basis generation, and model training into a modernized Python-based workflow, while retaining high-efficiency Fortran kernels for processing dynamics interfaces. Key features include GPU-accelerated training via TensorFlow, the robust Levenberg–Marquardt optimizer for high-precision fitting, real time monitoring via Jupyter and Tensorboard, and an active learning module that is built on top of these. We demonstrate the capabilities of CQPES through four representative case studies: CH4 to benchmark high-symmetry handling, CH3CN for a typical unimolecular isomerization reaction, OH + CH3OH to test GPU training acceleration on a large system, and Ar + H2O to validate the active learning module. Furthermore, CQPES provides direct interfaces with established dynamics software such as Gaussian 16, Polyrate 2017-C, VENUS96C, RPMDRate v2.0, and Caracal v1.1, enabling immediate application in chemical kinetics and dynamics simulations.

Chemistry doi: 10.3390/chemistry7060200

Authors: Mario Pagliaro Adele Muscolo Mariateresa Russo Francesco Mauriello Giuseppe Avellone Paolo Salvatore Calabrò Rosaria Ciriminna

Learning how discoveries in chemistry are made and utilized by the users of innovation in chemistry offers several benefits both to chemistry innovation practitioners and to research policy makers. We study the research and societal impact of three discoveries in chemistry reported between 2002 and 2022. The analysis confirms that, also in chemistry, science does not develop in a linear fashion, and that scientific developments continue to occur, driven by curiosity from self-determined researchers whose work is driven by intrinsic motivation relying on intellectual gratification. Companies in numerous industrial sectors, well beyond the chemical industrial sector, greatly benefit from chemistry innovation developed at public research institutes and universities. An obvious consequence is that policy makers should continue to support the work of chemistry research institutions using taxpayer money, leaving researchers free to choose research topics and the way to conduct research.

Chemistry doi: 10.3390/chemistry7060199

Authors: Esther Olajumoke Olagunju Matthew Alexander

Antibiotic residues such as ciprofloxacin in aquatic systems contribute to antimicrobial resistance and environmental contamination. Conventional treatment processes are often insufficient for removing pharmaceutical contaminants. In this study, activated carbon synthesized from coconut husk using orthophosphoric acid was evaluated for ciprofloxacin adsorption through equilibrium, kinetic, and thermodynamic analyses. The adsorption capacities were 42.34 mg/g for commercial activated carbon (AC) and 36.72 mg/g for synthesized coconut husk activated carbon (CHAC), at an initial ciprofloxacin concentration of 50 mg/L, achieving 85% and 73% removal, respectively. The experimental data obtained were analyzed using five isotherm models (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips). The Sips isotherm better describes AC sorption data than the Freundlich isotherm model for the CHAC, indicating heterogeneous surface coverage. The kinetic model investigation showed a better fit with the Elovich model for AC and the pseudo-second-order model for CHAC, as indicated by higher R2 values and lower sum-of-squares errors. Thermodynamic parameters indicated spontaneous and exothermic processes, while SEM analysis confirmed surface porosity and heterogeneity. The results demonstrate that the chemically activated coconut husk is an efficient, low-cost, and sustainable material for mitigating pharmaceutical contamination and addressing antimicrobial resistance in water systems.

Chemistry doi: 10.3390/chemistry7060198

Authors: Linda Zh. Nikoshvili Elena S. Bakhvalova Mikhail G. Sulman

At present, various carbon materials are available as supports for metal-containing catalytic species. Carbon-based materials find application in many industrial heterogeneous catalytic processes, such as selective hydrogenation, oxidation, cross-coupling, etc. The simplicity of preparation, low cost, high stability, and the possibility of tuning surface composition and porosity cause the widespread use of metal catalysts supported on carbon materials. The surface chemistry of carbon supports plays a crucial role in catalysis, since it allows for control over the sizes of metal particles and their electronic properties. Moreover, metal-free functionalized carbonaceous materials themselves can act as catalysts. In this review, we discuss the recent progress in the field of the application of carbon supports in catalysis by metals, with a focus on the role of carbon surface functionalities and metal-support interactions in catalytic processes used in fine organic synthesis. Among carbon materials, functionalized/doped (O, N, S, P, B) activated carbons, graphenes, carbon nanotubes, graphitic carbon nitride, and carbonizates of polymers are considered supports for mono- and bimetallic nanoparticles.

Chemistry doi: 10.3390/chemistry7060197

Authors: Junjie Xu Bingyan Wang Yuhao Wang Jinyu Yang Changxin Li

The excessive use of tetracycline (TC) poses a severe threat to the health of humans and ecosystems. Environmentally friendly photocatalytic technology can be effectively used to degrade TC. In this study, an Fe-modified UIO-66 (Fe/UIO-66) catalyst was prepared via a solvothermal method. The structural and optical properties were investigated to elucidate how the electronic interaction between Fe and UIO-66 influenced the light absorption capacity of Fe/UIO-66. A xenon lamp was used to simulate sunlight, and TC was taken as the target pollutant. The results of photocatalytic experiments showed that the degradation efficiency of Fe/UIO-66 for TC reached 80% within 120 min, superior to that of UIO-66. In addition, the experiment also investigated the influence of inorganic salt ions on the catalytic performance, proving that Fe/UIO-66 could be applied for the efficient removal of TC in complex water bodies.

Chemistry doi: 10.3390/chemistry7060196

Authors: Juan C. Segura-Silva Miguel A. Cabrera-Briseño Ricardo González-Cruz Sara A. Cortes-Llamas José G. Alvarado-Rodríguez Elvia Becerra-Martínez A. Aaron Peregrina-Lucano I. Idalia Rangel-Salas

This study describes a series of water-soluble half-sandwich ruthenium(II), rhodium(III), and iridium(III) complexes with α-diimine ligands containing substituted aromatic groups. These ligands were derived from glyoxal and 2-aminophenol (a), 4-methyl-2-aminophenol (b), 4-aminophenol (c), phenyl hydrazine (d), and 1-aminonaphthalene (e). The ruthenium(II) (1b–1e), rhodium(III) (2a–2c, 2e), and iridium(III) complexes (3a–3e) were obtained by reacting the ligands (a–e) with the corresponding dimeric precursor [(η6-p-cym)RuCl2]2 (p-cym = p-cymene) or [(η5-Cp*)MCl2]2 (Cp* = pentamethylcyclopentadienyl, M = Rh, Ir) in air and under nonanhydro conditions. The air-stable and water-soluble ruthenium(II), rhodium(III), and iridium(III) complexes were characterized via nuclear magnetic resonance spectroscopy and electrospray ionization–mass spectrometry. The structures of complexes [(η6-p-cym)Ru(d)Cl]Cl, 1d; [(η5-Cp*)Ir(a)Cl]Cl, 3a; and [(η5-Cp*)Ir(c)Cl]Cl, 3c were determined via single-crystal X-ray diffraction. Additionally, the complexes exhibited catalytic activity as precatalysts in formic acid decomposition. Complex [(η5-Cp*)Ir(d)Cl]Cl, 3d achieved turnover number (TON) and turnover frequency (TOF) values of up to 2150 and 3861 h−1, respectively, at short reaction times. In the hydrogenation of carbon dioxide, [(η6-p-cym)Ru(e)Cl]Cl, 1e attained TON and TOF values of up to 1385 and 69.25 h−1, respectively.

Chemistry doi: 10.3390/chemistry7060195

Authors: Xiu Chen Chen Huang Haidong Li Suoqi Zhao Linzhou Zhang

The presence of vanadium compounds in heavy oils poses a significant challenge by poisoning and deactivating refining catalysts, making their removal an essential processing step. However, this process is challenged by the competitive adsorption of abundant polycyclic aromatic hydrocarbons (PAHs) in heavy oils, due to the similar conjugated π-electron structure of PAHs and vanadyl porphyrins. In the presented study, the adsorption behaviors of vanadyl octaethylporphyrin (VOOEP) and 1-methylpyrene (1-MP) on various solid adsorbents were investigated. Among the adsorbents studied, the primary secondary amine adsorbent (PSA) demonstrated superior performance, achieving high VOOEP adsorption capacity and exceptional selectivity, even in the presence of a large excess of 1-MP. The adsorption kinetics, isotherms, and thermodynamics of VOOEP and 1-MP onto PSA were studied. Four common kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion) were used for data fitting. The adsorption isotherms were modeled using Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The adsorption kinetics for both VOOEP and 1-MP on PSA were best described by the pseudo-second-order model, while equilibrium data were well fitted by the Freundlich isotherm. Thermodynamic analysis confirmed that the adsorption of VOOEP and 1-MP on PSA is a spontaneous and exothermic process. The practical applicability of PSA was confirmed with a heavy deasphalted oil (HDAO), where it efficiently removed vanadium with high selectivity, with lower co-adsorption of desirable oil components. The results indicate that PSA is a promising adsorbent for effectively removing vanadium compounds from heavy oils.

Chemistry doi: 10.3390/chemistry7060194

Authors: Ghania Dekkiche Yassine Chaker Abdelkader Benabdellah EL-Habib Belarbi Noureddine Harid Mustapha Hatti Abdelhalim Zoukel Abdelaziz Rabehi Mustapha Habib

In this work, nickel oxide nanoparticles (NiO NPs) were synthesized sonochemically in the ionic liquid 1,2-(propanediol)-3-methylimidazolium hydrogen sulfate ([PDOHMIM+][HSO4−]) at different loadings (8 wt.%, 15 wt.%, and 30 wt.%), and subsequently coated with polyethylene glycol (PEG). Structural characterization (XRD, FTIR, TEM, TGA) confirmed a cubic NiO spinel phase with an average crystallite size of ~8 nm, which increased to 20–28 nm after PEG coating. Electrical measurements (100 Hz–1 MHz) showed that AC conductivity (σAC) increased with both frequency and NiO content, whereas the dielectric constant (ε′) and loss tangent (tan δ) decreased with frequency. DFT calculations (B3LYP/6–311+G(2d,p)) on the [PDOHMIM+][HSO4−] ion pair showed that there were strong hydrogen bonds, an uneven charge distribution, and stable electrostatic interactions that help keep NiO NPs stable and spread them evenly in the ionic liquid. In general, both experimental and theoretical studies show that PEG-coated [NiO NPs + IL] nanostructures exhibit improved dielectric stability, enhanced interfacial polarization, and tunable electronic properties.

Chemistry doi: 10.3390/chemistry7060193

Authors: Mei Yang Shaobai Wen Jun Zhang Xiangxiang Li Chunwei Yu

Most reported fluorescent Al3+ probes rely on fluorescence signal enhancement or quenching. Since the change in fluorescence intensity is the sole detection signal, various factors such as instrumental efficiency, environmental conditions, and probe concentration can interfere with the signal output. In contrast, ratiometric probes, which utilize two emission bands for self-calibration, provide significant advantages by minimizing or eliminating these uncertainties. In this study, a naphthalimide-rhodamine based the transition between the cyclic and open-ring forms of rhodamine as an Al3+-selective ratiometric probe, in which chitosan was identified as an ideal bridge and biocompatibility. The design concept was that when the target metal ion was present, the fluorescence intensity of naphthalimide remained largely unchanged, serving as an internal standard. In contrast, rhodamine B was employed to label the target molecules, with its fluorescence intensity varying in accordance with the target concentration. A series of experiments were carried out to investigate the fluorometric properties of the grafted polymer P. The results demonstrated that P exhibited selective interaction with Al3+ among the various metals tested. Using the fluorescence intensity ratio (I603 nm/I538 nm) of P, a good linear relationship was achieved for Al3+ concentrations ranging from 1.0 to 35.0 μM with a detection limit of 0.33 μM was obtained. Meanwhile, we employed the standard addition method for the quantitative analysis and detection of Al3+ in commercially available bottled water and tap water, achieving an ideal recovery rate.

Chemistry doi: 10.3390/chemistry7060192

Authors: Peter L. Rodríguez-Kessler Alvaro Muñoz-Castro

Cyclo[48]carbon (C48) exhibits an aesthetically pleasant structure featuring a cyclic polyyne, and it serves as a prototypical medium-sized ring that moves us towards an understanding of its overall magnetic behavior in a challenging molecular shape through analysis of its induced magnetic field. The isotropic induced magnetic field (NICS) profile shows a strong deshielding region at the ring center and a shielding region near the carbon rim, indicating antiaromatic behavior. Under a perpendicular magnetic field, a pronounced deshielding cone extends from the ring center, whereas a parallel external field induces a localized shielding near the carbon backbone. This results in significant magnetic anisotropy above and below the ring plane, characteristic of its medium-sized cyclic structure. Decomposition of the magnetic shielding highlights that paramagnetic effects predominantly govern the magnetic response and anisotropy of C48, with diamagnetic contributions playing a minor role. These insights suggest that chemical modifications targeting frontier orbitals could effectively tune the magnetic properties of cyclo[48]carbon, providing a foundation for the design of substituted derivatives with tailored diamagnetic anisotropy for advanced material applications.