Chemistry

15 pages, 1130 KB

Open AccessArticle

Determination of Energy Interaction Parameters for the UNIFAC Model Based on Solvent Activity Coefficients in Benzene–D2EHPA and Toluene–D2EHPA Systems

by Vladimir Glebovich Povarov, Olga Vladimirovna Cheremisina and Daria Artemovna Alferova

Chemistry 2026, 8(1), 2; https://doi.org/10.3390/chemistry8010002 - 23 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Physical Chemistry and Chemical Physics)

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23 pages, 3772 KB

Open AccessReview

Benzimidazole Derivatives: A Review of Advances in Synthesis, Biological Potential, Computational Modelling, and Specialized Material Functions

by Nuaman F. Alheety, Sameer A. Awad, Mustafa A. Alheety, Mohanned Y. Darwesh, Jalal A. Abbas and Rafaâ Besbes

Chemistry 2026, 8(1), 1; https://doi.org/10.3390/chemistry8010001 - 19 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Advances in Rational Drug Design: From Target Identification to Drug Lead Compounds)

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18 pages, 6466 KB

Open AccessArticle

Copper-Mediated Leaching of LiCoO₂ in H₃PO₄: Kinetics and Residue Transformation

by Dragana Medić, Ivan Đorđević, Maja Nujkić, Vladan Nedelkovski, Aleksandra Papludis, Stefan Đorđievski and Nataša Gajić

Chemistry 2025, 7(6), 203; https://doi.org/10.3390/chemistry7060203 - 17 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Green and Environmental Chemistry)

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13 pages, 3264 KB

Open AccessArticle

Insight into the Adsorption Behavior of Cd(II) and Pb(II) from Mud by HCl-Modified Coconut Shell Biochar: Experimental and DFT Studies

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

Chemistry 2025, 7(6), 202; https://doi.org/10.3390/chemistry7060202 - 17 Dec 2025

Abstract

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 [...] Read more.

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). Full article

(This article belongs to the Section Green and Environmental Chemistry)

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22 pages, 6309 KB

Open AccessTutorial

CQPES: A GPU-Aided Software Package for Developing Full-Dimensional Accurate Potential Energy Surfaces by Permutation-Invariant-Polynomial Neural Network

by Junhong Li, Kaisheng Song and Jun Li

Chemistry 2025, 7(6), 201; https://doi.org/10.3390/chemistry7060201 - 17 Dec 2025

Abstract

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, [...] Read more.

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. Full article

(This article belongs to the Collection Featured Reviews, Perspectives, and Commentaries in Contemporary Chemistry)

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13 pages, 860 KB

Open AccessArticle

How Are Discoveries in Chemistry Made? Insight from Three Discoveries and Their Impact

by Mario Pagliaro, Adele Muscolo, Mariateresa Russo, Francesco Mauriello, Giuseppe Avellone, Paolo Salvatore Calabrò and Rosaria Ciriminna

Chemistry 2025, 7(6), 200; https://doi.org/10.3390/chemistry7060200 - 16 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Celebrating the 50th Anniversary of Professor Valentine Ananikov)

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21 pages, 3282 KB

Open AccessArticle

Valorization of Coconut Husk for Mitigating Antimicrobial Resistance: Mechanistic Insights into Ciprofloxacin Removal from Water

by Esther Olajumoke Olagunju and Matthew Alexander

Chemistry 2025, 7(6), 199; https://doi.org/10.3390/chemistry7060199 - 11 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Green and Environmental Chemistry)

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41 pages, 5530 KB

Open AccessReview

The Role of Surface Chemistry in Carbon-Supported Metal-Catalyzed Processes of Fine Organic Synthesis

by Linda Zh. Nikoshvili, Elena S. Bakhvalova and Mikhail G. Sulman

Chemistry 2025, 7(6), 198; https://doi.org/10.3390/chemistry7060198 - 11 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Celebrating the 50th Anniversary of Professor Valentine Ananikov)

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9 pages, 2016 KB

Open AccessArticle

Electron Interaction-Enhanced Photocatalytic Degradation of Tetracycline over Fe/UIO-66

by Junjie Xu, Bingyan Wang, Yuhao Wang, Jinyu Yang and Changxin Li

Chemistry 2025, 7(6), 197; https://doi.org/10.3390/chemistry7060197 - 11 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Modern Photochemistry and Molecular Photonics)

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21 pages, 2917 KB

Open AccessArticle

Ruthenium, Rhodium, and Iridium α-Diimine Complexes as Precatalysts in Carbon Dioxide Hydrogenation and Formic Acid Decomposition

by 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 and I. Idalia Rangel-Salas

Chemistry 2025, 7(6), 196; https://doi.org/10.3390/chemistry7060196 - 4 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Catalysis)

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19 pages, 2087 KB

Open AccessArticle

Selective Adsorption of Vanadyl Porphyrin on Solid Adsorbent in the Presence of Polycyclic Aromatic Hydrocarbon: Kinetics, Equilibrium, and Thermodynamic Studies

by Xiu Chen, Chen Huang, Haidong Li, Suoqi Zhao and Linzhou Zhang

Chemistry 2025, 7(6), 195; https://doi.org/10.3390/chemistry7060195 - 4 Dec 2025

Abstract

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, [...] Read more.

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. Full article

(This article belongs to the Section Molecular Organics)

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20 pages, 4154 KB

Open AccessArticle

PEG-Coated Nanostructured NiO Synthesized Sonochemically in 1,2-(Propanediol)-3-methylimidazolium Hydrogen Sulfate Ionic Liquid: DFT, Structural and Dielectric Characterization

by Ghania Dekkiche, Yassine Chaker, Abdelkader Benabdellah, EL-Habib Belarbi, Noureddine Harid, Mustapha Hatti, Abdelhalim Zoukel, Abdelaziz Rabehi and Mustapha Habib

Chemistry 2025, 7(6), 194; https://doi.org/10.3390/chemistry7060194 - 4 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Chemistry at the Nanoscale)

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15 pages, 1999 KB

Open AccessArticle

Construction of an Internal Standard Ratiometric Al³⁺ Selective Fluorescent Probe Based on Rhodamine B-Modified Naphthalimide-Grafted Chitosan Polymer

by Mei Yang, Shaobai Wen, Jun Zhang, Xiangxiang Li and Chunwei Yu

Chemistry 2025, 7(6), 193; https://doi.org/10.3390/chemistry7060193 - 3 Dec 2025

Abstract

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, [...] Read more.

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 (I_{603 nm}/I_{538 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. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors and Probes for Detection and Imaging)

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10 pages, 1733 KB

Open AccessArticle

Cyclo[48]carbon—Evaluation of Its Inherent Magnetic Behavior and Anisotropy from DFT Calculations

by Peter L. Rodríguez-Kessler and Alvaro Muñoz-Castro

Chemistry 2025, 7(6), 192; https://doi.org/10.3390/chemistry7060192 - 1 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Aromaticity and Antiaromaticity: Refining Concepts and Expanding Perspectives)

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21 pages, 2859 KB

Open AccessArticle

Microwave-Irradiated Eco-Friendly Multicomponent Synthesis of Substituted Pyrazole Derivatives and Evaluation of Their Antibacterial Potential

by Bahle L. Mntambo, Jamiu O. Aribisala, Saheed Sabiu, Senzekile Majola, Robert M. Gengan and Talent R. Makhanya

Chemistry 2025, 7(6), 191; https://doi.org/10.3390/chemistry7060191 - 1 Dec 2025

Abstract

The synthesis of novel pyrazole derivatives (SPDs) and their evaluation for antibacterial potential against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), and Streptococcus pneumoniae (S. pneumoniae) was developed herein. These [...] Read more.

The synthesis of novel pyrazole derivatives (SPDs) and their evaluation for antibacterial potential against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), and Streptococcus pneumoniae (S. pneumoniae) was developed herein. These compounds were obtained via a microwave-assisted eco-friendly multicomponent reaction (MCR) and were characterized for structural confirmation using ¹H NMR, ¹³C NMR, 2D experiments, TOF-MS, and FTIR spectrometry. Antibacterial activity, as measured by minimum inhibitory concentrations (MICs) of SPDs, ranged between 0.212 and 2.50 mg/mL against S. aureus, S. pneumoniae, P. aeruginosa, and E. coli. Compound 4e was the most potent against S. pneumoniae, with an MIC value of 0.0156 mg/mL compared with Amoxicillin’s MIC value of 0.0306 mg/mL. Thus, compound 4e was observed as a potential lead candidate against S. pneumoniae. Further corroboration by molecular docking at the active site of the key penicillin-binding protein (PBP) revealed that the most potent compounds against each organism showed comparable docking scores to those of amoxicillin. In addition, a pharmacokinetics study showed that synthesized SPDs were predicted to be orally bioavailable and non-inhibitors of cytochrome 3A4 and belong to drug classes 4 and 6. Hence, they were suitable for drug development and warrant further studies such as in vitro assays, in silico modeling, DFT studies, and machine learning for drug design. Full article

(This article belongs to the Section Medicinal Chemistry)

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21 pages, 6220 KB

Open AccessReview

High-Entropy Alloys for Electrocatalytic Water Oxidation: Recent Advances on Mechanism and Design

by Luyu Liu, Xiang Ding, Haotian Qin, Siyuan Tang, Linlin Xu and Fuzhan Song

Chemistry 2025, 7(6), 190; https://doi.org/10.3390/chemistry7060190 - 28 Nov 2025

Abstract

Hydrogen energy has been regarded as a promising alternative to fossil fuels due to its high energy density and zero-pollution combustion nature. Compared to other hydrogen generation technologies, water electrolysis provides a promising route for high-purity hydrogen production. Therefore, the development of efficient [...] Read more.

Hydrogen energy has been regarded as a promising alternative to fossil fuels due to its high energy density and zero-pollution combustion nature. Compared to other hydrogen generation technologies, water electrolysis provides a promising route for high-purity hydrogen production. Therefore, the development of efficient electrocatalysts is of great significance. Particularly, high-entropy engineering strategies supply a novel multi-principal element catalyst platform due to their unique structural and electronic properties. This work systematically summarizes recent advancements on high-entropy alloys (HEAs) catalysts on electrocatalytic water oxidation. Especially, it focuses on elucidating two competing fundamental mechanisms: the adsorbate evolution mechanism (AEM) and the lattice oxygen-mediated mechanism (LOM), via high-entropy engineering, which can efficiently modulate electronic configurations and adsorption/desorption behavior. This work aims to supply a theoretical foundation and rational design principles for developing next-generation OER catalysts with high activity and stability. Full article

(This article belongs to the Collection Featured Reviews, Perspectives, and Commentaries in Contemporary Chemistry)

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17 pages, 1724 KB

Open AccessArticle

Adsorption of Crystal Violet Using Kaolin-Based Geopolymer

by Joshua Nosa Edokpayi

Chemistry 2025, 7(6), 189; https://doi.org/10.3390/chemistry7060189 - 26 Nov 2025

Cited by 1

Abstract

The removal of synthetic dyes from water resources is essential for environmental protection and sustainable water management. This study aimed to develop and evaluate a kaolin-based geopolymer (KBG) for the adsorption of crystal violet (CV) dye from aqueous solutions. Natural kaolin, an abundant [...] Read more.

The removal of synthetic dyes from water resources is essential for environmental protection and sustainable water management. This study aimed to develop and evaluate a kaolin-based geopolymer (KBG) for the adsorption of crystal violet (CV) dye from aqueous solutions. Natural kaolin, an abundant aluminosilicate material in South Africa, was activated using an alkaline solution to form the geopolymer. The synthesized material was characterized using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. Batch adsorption experiments were conducted to investigate the effects of contact time (5–180 min), adsorbent dosage (0.05–1.0 g), initial dye concentration (10–150 mg/L), temperature (30–50 °C), pH (2–12), and water chemistry on CV removal efficiency. Characterization results confirmed the successful conversion of kaolin to geopolymer, exhibiting a BET surface area of 11.18 m²/g. The optimum adsorption occurred at pH 10.2, where electrostatic attraction between the negatively charged geopolymer surface and the cationic dye molecules was maximized. Kinetic data fitted best to the pseudo-second-order model, while the Langmuir isotherm provided the best description of the equilibrium data. The adsorption mechanism was attributed to electrostatic attraction, hydrogen bonding, and π–π interactions between CV molecules and the geopolymer surface. Thermodynamic analysis confirmed that the adsorption process was spontaneous and endothermic, indicating enhanced dye uptake at elevated temperatures. Full article

(This article belongs to the Section Green and Environmental Chemistry)

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13 pages, 15558 KB

Open AccessArticle

A Bacteria Sol–Gel Template Approach to Form Palladium Core–Shell Catalysts for Suzuki–Miyaura Reactions

by Vitaliy N. Soromotin, Pavel V. Rybochkin, Violetta A. Pertseva and Olga A. Kamanina

Chemistry 2025, 7(6), 188; https://doi.org/10.3390/chemistry7060188 - 25 Nov 2025

Abstract

This study presents a sustainable and efficient method for fabricating core–shell structured palladium catalysts using a bacterial template and sol–gel synthesis. This synthesis aligns with green chemistry principles by minimizing waste and enhancing resource efficiency. Our results demonstrate that the bacterial template effectively [...] Read more.

This study presents a sustainable and efficient method for fabricating core–shell structured palladium catalysts using a bacterial template and sol–gel synthesis. This synthesis aligns with green chemistry principles by minimizing waste and enhancing resource efficiency. Our results demonstrate that the bacterial template effectively stabilizes Pd nanoparticles (NPs), preventing significant agglomeration during synthesis and subsequent calcination under different atmospheres and final temperatures. The catalyst samples were characterized by SEM, TEM, XRD, and TGA. The 1 wt% Pd/R@SiO₂ catalyst exhibited high activity in the Suzuki–Miyaura cross-coupling reaction, achieving competitive yields. Furthermore, the catalyst demonstrated a stable performance over five consecutive cycles. This work underscores the potential of biotemplated synthesis as a versatile and eco-friendly platform for producing high-performance, tunable catalysts. Full article

(This article belongs to the Special Issue Celebrating the 50th Anniversary of Professor Valentine Ananikov)

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21 pages, 3437 KB

Open AccessArticle

N/S Co-Doped Mesoporous Carbon Hollow Spheres: Toward Efficient and Durable Oxygen Reduction

by I. L. Alonso-Lemus, J. C. Carrillo-Rodríguez, B. Escobar-Morales and F. J. Rodríguez-Varela

Chemistry 2025, 7(6), 187; https://doi.org/10.3390/chemistry7060187 - 24 Nov 2025

Abstract

This study reports the design of N- and S-doped ordered mesoporous carbon hollow spheres (OMCHS) as metal-free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media. Three electrocatalysts were synthesized using molecular precursors: (i) 2-thiophenemethanol (S-OMCHS), (ii) 2-pyridinecarboxaldehyde/2-thiophenemethanol (N1-S-OMCHS), and (iii) pyrrole/2-thiophenemethanol [...] Read more.

This study reports the design of N- and S-doped ordered mesoporous carbon hollow spheres (OMCHS) as metal-free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media. Three electrocatalysts were synthesized using molecular precursors: (i) 2-thiophenemethanol (S-OMCHS), (ii) 2-pyridinecarboxaldehyde/2-thiophenemethanol (N1-S-OMCHS), and (iii) pyrrole/2-thiophenemethanol (N2-S-OMCHS). Among them, S-OMCHS exhibited the best activity (E_onset = 0.88 V, E_½ = 0.81 V, n ≈ 3.95), surpassing both co-doped analogs. After conducting an accelerated degradation test (ADT), S-OMCHS and N1-S-OMCHS showed improved catalytic behavior and outstanding long-term stability. Surface analysis confirmed that performance evolution correlates with heteroatom reorganization: S-OMCHS retained and regenerated thiophene-S and C=O/quinone species, while N1-S-OMCHS converted N-quaternary into N-pyridinic/pyrrolic, both enhancing O₂ adsorption and *OOH reduction through synergistic spin–charge coupling. Conversely, oxidation of N and loss of thiophene-S in N2-S-OMCHS led to partial deactivation. These results establish a direct link between surface chemistry evolution and electrocatalytic durability, demonstrating that controlled heteroatom doping stabilizes active sites and sustains the four-electron ORR pathway. The approach provides a rational design framework for next-generation, metal-free carbon electrocatalysts in alkaline fuel cells and energy conversion technologies. Full article

(This article belongs to the Section Electrochemistry and Photoredox Processes)

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