Molecules

19 pages, 5729 KiB

Open AccessArticle

Highly Engineered Cr-In/H-SSZ-39 Catalyst for Enhanced Performance in CH₄-SCR of NO_x

by Jiuhu Zhao, Jingjing Jiang, Guanyu Chen, Meng Wang, Xiaoyuan Zuo, Yanjiao Bi and Rongshu Zhu

Molecules 2025, 30(13), 2691; https://doi.org/10.3390/molecules30132691 (registering DOI) - 21 Jun 2025

Abstract

The selective catalytic reduction of NO_x with CH₄ (CH₄-SCR) holds the potential to simultaneously abate harmful NO_x and CH₄ greenhouse gases. In this study, a series of bimetallic M-In/H-SSZ-39 catalysts (where M represents Cr, Co, Ce, and [...] Read more.

The selective catalytic reduction of NO_x with CH₄ (CH₄-SCR) holds the potential to simultaneously abate harmful NO_x and CH₄ greenhouse gases. In this study, a series of bimetallic M-In/H-SSZ-39 catalysts (where M represents Cr, Co, Ce, and Fe) were prepared via an ion exchange method and subsequently evaluated for their CH₄-SCR activity. The influences of the preparation parameters, including the metal ion concentration and calcination temperature, as well as the operating conditions, such as the CH₄/NO ratio, O₂ concentration, water vapor content, and gas hourly space velocity (GHSV), on the catalytic activity of the optimal Cr-In/H-SSZ-39 catalyst were meticulously examined. The results revealed that the Cr-In/H-SSZ-39 catalyst exhibited peak CH₄-SCR catalytic performance when the Cr(NO₃)₃ concentration was 0.0075 M, the In(NO₃)₃ concentration was 0.066 M, and the calcination temperature was 500 °C. Under optimal operating conditions, namely GHSV of 10,000 h⁻¹, 400 ppm NO, 800 ppm CH₄, 15 vol% O₂, and 6 vol% H₂O, the NO_x conversion rate reached 93.4%. To shed light on the excellent performance of Cr-In/H-SSZ-39 under humid conditions, a comparative analysis of the crystalline phase, chemical composition, pore structure, surface chemical state, surface acidity, and redox properties of Cr-In/H-SSZ-39 and In/H-SSZ-39 was conducted. The characterization results indicated that the incorporation of Cr into In/H-SSZ-39 enhanced its acidity and also facilitated the generation of InO⁺ active species, which promoted the oxidation of NO and the activation of CH₄, respectively. A synergistic effect was observed between Cr and In species, which significantly improved the redox properties of the catalyst. Consequently, the activated CH₄ could further interact with InO⁺ to produce carbon-containing intermediates such as HCOO⁻, which ultimately reacted with nitrate-based intermediates to yield N₂, CO₂, and H₂O. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis for Sustainability and Carbon-Neutrality)

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17 pages, 2590 KiB

Open AccessArticle

Enhanced Oxidation of Carbamazepine Using Mn(II)-Activated Peracetic Acid: A Novel Advanced Oxidation Process Involving the Significant Role of Ligand Effects

by Xue Yang, Hai Yu, Liang Hong, Zhihang Huang, Qinda Zeng, Xiao Yao and Yinyuan Qiu

Molecules 2025, 30(13), 2690; https://doi.org/10.3390/molecules30132690 (registering DOI) - 21 Jun 2025

Abstract

In recent years, extensive attention has been paid to advanced oxidation processes (AOPs) with peracetic acid (PAA), a widely used disinfectant, using transition metal ions for the degradation of organic contaminants within water environments. Mn(II) has been widely used as an effective homogeneous [...] Read more.

In recent years, extensive attention has been paid to advanced oxidation processes (AOPs) with peracetic acid (PAA), a widely used disinfectant, using transition metal ions for the degradation of organic contaminants within water environments. Mn(II) has been widely used as an effective homogeneous transition metal catalyst for oxidant activation, but it has shown poor performances with PAA. Since the stability of manganese species can be enhanced through the addition of ligands, this study systematically investigated a novel AOP for the oxidation of carbamazepine (CBZ) using an Mn(II)/PAA system with several different ligands added. The reactive species were explored through UV-vis spectrometry, scavengers, and probe compounds. The results suggest that Mn(III)–ligand complexes and other high-valent Mn species (Mn(V)) were generated and contributed obviously toward efficient CBZ oxidation, while radicals like CH₃CO₂^• and CH₃CO₃^• were minor contributors. The oxidation efficiency of Mn(II)/PAA/ligands depended highly on ligand species, as ethylene diamine tetraacetic acid (EDTA) and oxalate (SO) could promote the oxidation of CBZ, while pyrophosphate (PPP) showed modest enhancement. The results obtained here might contribute to the removal of residue pharmaceuticals under manganese-rich waters and also shed light on PAA-based AOPs that could help broaden our present knowledge of manganese chemistry for decontamination in water treatment. Full article

(This article belongs to the Special Issue Advanced Oxidation/Reduction Processes in Water Treatment)

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14 pages, 2064 KiB

Open AccessArticle

Paramagnetic and Luminescent Properties of Gd(III)/Eu(III) Ascorbate Coordination Polymers

by Marco Ricci and Fabio Carniato

Molecules 2025, 30(13), 2689; https://doi.org/10.3390/molecules30132689 (registering DOI) - 21 Jun 2025

Abstract

Gadolinium-based contrast agents (GBCAs) are the gold standard as MRI probes but are nowadays facing medical limitations and environmental concerns. To address these issues, novel strategies focus on the optimization of Gd(III)-based probes. One promising approach involves incorporating Gd(III) into nanoparticles, particularly coordination [...] Read more.

Gadolinium-based contrast agents (GBCAs) are the gold standard as MRI probes but are nowadays facing medical limitations and environmental concerns. To address these issues, novel strategies focus on the optimization of Gd(III)-based probes. One promising approach involves incorporating Gd(III) into nanoparticles, particularly coordination polymers, which offer improved relaxivity. In this study, we explore the self-assembly of Gd(III) ions with ascorbate ligand, forming extended coordination polymer architectures. Our investigation focuses on understanding the impact of nanoparticles’ growth and aggregation on their relaxivity properties. Notably, the controlled aggregation process leads to a different distribution of the Gd(III) in the surface and in the bulk of the nanoparticles, mainly responsible for their longitudinal relaxivity. Additionally, the introduction of Eu(III) into the network enables the development of a dual-modal probe with paramagnetic and optical features. Full article

(This article belongs to the Special Issue Metal Complexes for Optical and Electronics Applications)

26 pages, 3407 KiB

Open AccessArticle

Novel Azole-Modified Porphyrins for Mitochondria-Targeted Photodynamic Therapy

by Sabarinathan Rangasamy, Elisa Bandini, Alessandro Venturini, Giuseppina Bozzuto, Sofia Migani, Annarica Calcabrini, Simona Sennato, Caterina Zuffa, Lucia Maini, Anaïs Brion, Frédéric Bolze, Cecilia Bombelli and Barbara Ventura

Molecules 2025, 30(13), 2688; https://doi.org/10.3390/molecules30132688 (registering DOI) - 21 Jun 2025

Abstract

Photodynamic therapy is a non-invasive treatment strategy for various types of cancer, based on the use of light to activate a photosensitizer which triggers processes leading to cell death. Given the increasing interest in the development of mitochondria-targeted photosensitizers, in this study we [...] Read more.

Photodynamic therapy is a non-invasive treatment strategy for various types of cancer, based on the use of light to activate a photosensitizer which triggers processes leading to cell death. Given the increasing interest in the development of mitochondria-targeted photosensitizers, in this study we synthesized two novel thiadiazol-substituted porphyrins, 5,10,15,20-tetra(2,1,3-benzothiadiazol-5-yl) porphyrin (C1) and 5,10,15,20-tetra(1,2,3-thiadiazol-4-yl) porphyrin (C2), designed to target mitochondria in cancer cells thanks to the azole residues present in their structure. The two porphyrinic compounds were characterized in terms of structural and photophysical properties, revealing high yields of singlet oxygen production. Their interaction with biological structures was analyzed in a triple-negative human breast carcinoma cell line (MDA-MB-231), either as free compounds or delivered via mitochondriotropic liposome formulations. Both newly synthesized porphyrins entered MDA-MB-231 cells, with compound C2 demonstrating more efficient localization in the cytoplasm and in mitochondria. Dark and phototoxicity tests were also performed: both compounds proved to be effective phototoxic agents, with C2 showing the highest activity, making it a promising photosensitizer for mitochondria-targeted photodynamic therapy. Full article

(This article belongs to the Special Issue Porphyrin-Based Compounds: Synthesis and Application, 2nd Edition)

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27 pages, 2951 KiB

Open AccessArticle

The Influence of Cynips quercusfolii on the Content of Biofunctional Plant Metabolites in Various Morphological Parts of Quercus robur

by Anna Przybylska-Balcerek and Kinga Stuper-Szablewska

Molecules 2025, 30(13), 2687; https://doi.org/10.3390/molecules30132687 (registering DOI) - 21 Jun 2025

Abstract

English oak (Quercus robur) hosts over 200 species of galls formed by insect larvae, most notably the oak gall wasp (Cynips quercusfolii). These galls result from the abnormal growth of plant tissue in response to oviposition, acting as a [...] Read more.

English oak (Quercus robur) hosts over 200 species of galls formed by insect larvae, most notably the oak gall wasp (Cynips quercusfolii). These galls result from the abnormal growth of plant tissue in response to oviposition, acting as a shelter and nutrient source for the larvae. In addition, the galls trigger oxidative stress in the host plant, resulting in the increased production of reactive oxygen species (ROS). This stress response promotes the biosynthesis of antioxidant compounds, including phenolic acids, flavonoids, and tannins. To our knowledge, this is the first study to monitor seasonal changes in phenolic acids, flavonoids, and tannins in relation to C. quercusfolii infestation over a complete vegetation cycle using integrated UPLC profiling and statistical modeling PCA. For the first time, the contents of phenolic acids, flavonoids, and tannins were assessed throughout the vegetation cycle—from flowering to acorn fall. Results showed that galls affect the biochemical profile of the whole plant, suggesting a systemic response to local infection. The results provide new insights into oak defense responses and suggest that gall formation may be associated with systemic metabolic shifts potentially involved in stress mitigation. Furthermore, the study supports the further investigation of oak galls as a valuable source of polyphenols for pharmacological and industrial applications. Full article

(This article belongs to the Special Issue Metabolites of Biofunctional Interest from Plant Sources)

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43 pages, 3139 KiB

Open AccessReview

Focus on PD-1/PD-L1-Targeting Antibodies in Colorectal Cancer: Are There Options Beyond Dostarlimab, Nivolumab, and Pembrolizumab? A Comprehensive Review

by Mateusz Kciuk, Katarzyna Wanke, Weronika Kruczkowska, Beata Marciniak and Renata Kontek

Molecules 2025, 30(13), 2686; https://doi.org/10.3390/molecules30132686 (registering DOI) - 21 Jun 2025

Abstract

The PD-1/PD-L1 pathway has emerged as a critical target in colorectal cancer (CRC) immunotherapy, with pembrolizumab, nivolumab, and dostarlimab demonstrating significant clinical efficacy, particularly in microsatellite instability-high (MSI-H) and mismatch repair-deficient (dMMR) tumors. However, a growing number of additional PD-1/PD-L1 inhibitors, including AMP-224, [...] Read more.

The PD-1/PD-L1 pathway has emerged as a critical target in colorectal cancer (CRC) immunotherapy, with pembrolizumab, nivolumab, and dostarlimab demonstrating significant clinical efficacy, particularly in microsatellite instability-high (MSI-H) and mismatch repair-deficient (dMMR) tumors. However, a growing number of additional PD-1/PD-L1 inhibitors, including AMP-224, atezolizumab, avelumab, camrelizumab, durvalumab, envafolimab, sintilimab, spartalizumab, tislelizumab, and toripalimab, are currently under investigation, offering new possibilities for the expansion of treatment options. This review evaluates the therapeutic potential of these emerging agents, assessing their clinical development, mechanisms of action, and potential advantages over established therapies. Additionally, it explores key challenges such as primary and acquired resistance, limited efficacy in microsatellite-stable (MSS) CRC, and the complexities of combination strategies aimed at enhancing immunotherapeutic responses. By addressing these obstacles and highlighting prospects, this review provides insights into the evolving landscape of PD-1/PD-L1-targeted therapies in CRC and their potential to improve patient outcomes. Full article

(This article belongs to the Special Issue Innovative Anticancer Compounds and Therapeutic Strategies)

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17 pages, 3681 KiB

Open AccessArticle

Vibrational Spectroscopic and Quantum-Chemical Study of Indole–Ketone Hydrogen-Bonded Complexes

by Branislav Jović, Nataša Negru, Dušan Dimić and Branko Kordić

Molecules 2025, 30(13), 2685; https://doi.org/10.3390/molecules30132685 (registering DOI) - 21 Jun 2025

Abstract

This study investigates the structural and energetic properties of hydrogen-bonded complexes between indole and a range of aliphatic, cyclic, and aromatic ketones using a combined vibrational spectroscopic and quantum-chemical approach. FTIR measurements in CCl₄ revealed redshifts in the N-H stretching vibration of [...] Read more.

This study investigates the structural and energetic properties of hydrogen-bonded complexes between indole and a range of aliphatic, cyclic, and aromatic ketones using a combined vibrational spectroscopic and quantum-chemical approach. FTIR measurements in CCl₄ revealed redshifts in the N-H stretching vibration of indole upon complexation, with formation constants (K_a) ranging from 0.3 to 6.6 M⁻¹. Cyclohexanone displayed the strongest binding, while benzophenone exhibited the weakest interaction. Quantum-chemical calculations, employing CREST and MMFF94 conformational sampling, along with M06-2X/6-311++G(d,p) optimizations, confirmed the formation of hydrogen bonds and additional weak interactions that govern the stability of the complex. QTAIM analysis revealed moderate closed-shell hydrogen bonds with electron densities at the bond critical points (ρ) ranging from 0.010 to 0.019 a.u. and potential energy densities (V) from −18.4 to −36.4 kJ mol⁻¹. Multivariate regression analysis established strong correlations (R² = 0.928 and 0.957) between experimental binding constants and theoretical descriptors, including binding energy, NBO charge on oxygen atom, ionization potential, and electrophilicity index, highlighting the interplay between geometric, electronic, and global reactivity factors. This comprehensive study underlines the predictive power of spectroscopic and quantum descriptors for assessing hydrogen bonding in biologically relevant systems. Full article

(This article belongs to the Special Issue Computational Chemistry Insights into Molecular Interactions)

15 pages, 1765 KiB

Open AccessArticle

Proton and Metal Dication Affinities of Tetracyclic Imidazo[4,5-b]Pyridine-Based Molecules: Insights from Mass Spectrometry and DFT Analysis

by Lucija Vrban, Ingrid Ana Martinac, Marijana Hranjec, Marijana Pocrnić, Nives Galić, Renata Kobetić and Robert Vianello

Molecules 2025, 30(13), 2684; https://doi.org/10.3390/molecules30132684 (registering DOI) - 21 Jun 2025

Abstract

The imidazo[4,5-b]pyridine scaffold, a versatile heterocyclic system, is renowned for its biological and chemical significance, yet its coordination chemistry with biologically relevant metal dications remains underexplored. This study investigates the proton and metal dication affinities of twelve tetracyclic organic molecules based [...] Read more.

The imidazo[4,5-b]pyridine scaffold, a versatile heterocyclic system, is renowned for its biological and chemical significance, yet its coordination chemistry with biologically relevant metal dications remains underexplored. This study investigates the proton and metal dication affinities of twelve tetracyclic organic molecules based on the imidazo[4,5-b]pyridine core, focusing on their interactions with Ca(II), Mg(II), Zn(II), and Cu(II). Employing a dual approach of electrospray ionization mass spectrometry (ESI-MS) and density functional theory (DFT) calculations, we characterized the formation, stability, and structural features of metal–ligand complexes. ESI-MS revealed distinct binding behaviors, with Cu(II) and Zn(II) forming stable mono- and dinuclear complexes, often accompanied by reduction processes (e.g., Cu(II) to Cu(I)), while Ca(II) and Mg(II) exhibited lower affinities. DFT analysis elucidated the electronic structures and thermodynamic stabilities, highlighting the imidazole nitrogen as the primary binding site and the influence of regioisomeric variations on affinity. Substituent effects were found to modulate binding strength, with electron-donating groups enhancing basicity and metal coordination. These findings provide a comprehensive understanding of the coordination chemistry of imidazo[4,5-b]pyridine derivatives, offering insights into their potential applications in metalloenzyme modulation, metal-ion sensing, and therapeutic chelation. Full article

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17 pages, 3516 KiB

Open AccessArticle

Is the Greener Approach Better? Application of Electrochemistry in the Synthesis of Perylenediimides

by Patrycja Filipek, Agata Szlapa-Kula, Stanisław Krompiec, Krzysztof Zemlak, Bartłomiej Kula, Karol Erfurt and Michał Filapek

Molecules 2025, 30(13), 2683; https://doi.org/10.3390/molecules30132683 (registering DOI) - 21 Jun 2025

Abstract

Perylenediimides are an interesting group of compounds that are finding more and more applications. However, the synthetic route of obtaining and modifying them is usually very complicated, costly, and time-consuming. Therefore, the conducted research aimed to develop new, greener, electrochemical methods of obtaining [...] Read more.

Perylenediimides are an interesting group of compounds that are finding more and more applications. However, the synthetic route of obtaining and modifying them is usually very complicated, costly, and time-consuming. Therefore, the conducted research aimed to develop new, greener, electrochemical methods of obtaining unknown perylenediimides (containing 2-ethylhexyl at the nitrogen atom). For the products obtained in this way, optical and electrochemical studies were conducted and compared with DFT results (i.e., energy gaps and HOMO and LUMO levels). Asa result of optical studies, different emission wavelengths of two isomers originating from the same excitation wavelength were observed. Electrochemical studies also confirmed significant differences in properties between the obtained isomers. Spectroelectrochemical measurements were also performed; they revealed the electrochromic properties of the obtained isomers in the visible and near-infrared range. Considering all the properties (optical and (spectro)electrochemical), the obtained compounds have a high potential for use in optoelectronic devices. Moreover, unprecedented pi-expansion of cis-DBPDI via 1,2-bis(p-bromophenyl)acetylene Diels–Alder cycloaddition into the bay region was also realized successfully. Summing up, electrosynthesis and further pi-expansion via cycloaddition offer a sea of opportunities for obtaining nanographenes. Full article

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36 pages, 2656 KiB

Open AccessArticle

Systematic Characterization of In Vitro and In Vivo Metabolic Pathways and Identification of Novel Biomarkers of 26 Synthetic Cannabinoids

by Yudie Ning, Tao Wang, Xiao Yang, Fang Guo, Yingwen Xu, Yuan Zhang, Kaile Wang, Meng Hu, Zhe Chen, Zhiwen Wei and Keming Yun

Molecules 2025, 30(13), 2682; https://doi.org/10.3390/molecules30132682 (registering DOI) - 21 Jun 2025

Abstract

In recent years, the harms and abuse of synthetic cannabinoids (SCs) have attracted extensive attention in society. Their structures have been updated rapidly, which brings great challenges for continuous detection and drug identification. The aim of this study was to elucidate the metabolites [...] Read more.

In recent years, the harms and abuse of synthetic cannabinoids (SCs) have attracted extensive attention in society. Their structures have been updated rapidly, which brings great challenges for continuous detection and drug identification. The aim of this study was to elucidate the metabolites of 26 kinds of abused SCs produced in human liver microsomes (HLMs) and rats and to explore the metabolism of indole amides, indazole amides, azaindoles, naphthyl indoles, cyclopropylindoles, naphthyl benzimidazole, and naphthyl pyrrole SCs in vivo and in vitro. Human liver microsomes were incubated with SCs to simulate human metabolic processes, and the in vitro metabolic model of liver microsomes was established. After the SD rats were randomized into groups, 26 kinds of SCs and normal saline were injected respectively to establish the rat model after exposure. The metabolites were identified one by one using a UHPLC-Q-Exactive Orbitrap MS method to explore the metabolic law. A total of 609 metabolites were identified, involving 30 metabolic pathways. The metabolism of SCs was summarized from the parent nuclear group, the head group, the linking group, and the tail side chain, and the mass spectral fragmentation pattern of the metabolites was analyzed in order to provide reference for the examination and identification of SCs-related cases. Full article

(This article belongs to the Section Analytical Chemistry)

12 pages, 814 KiB

Open AccessArticle

Development of LC-MS/MS and GC-MS/MS Methods for the Detection of Ethyl Glucuronide (EtG) and Ethyl Palmitate (EtPa) in Hair

by Sharnette Ashiru, Ethan Webster, Benjamin Barrett, Mathew Wade and Brian Rooney

Molecules 2025, 30(13), 2681; https://doi.org/10.3390/molecules30132681 (registering DOI) - 21 Jun 2025

Abstract

Alcohol abuse is a widespread addiction globally, leading to long-term health issues and social consequences. Ethyl glucuronide (EtG) and ethyl palmitate (EtPa) are frequently requested by local authorities, solicitors, or private individuals to assess long-term chronic excessive alcohol consumption. In this paper, we [...] Read more.

Alcohol abuse is a widespread addiction globally, leading to long-term health issues and social consequences. Ethyl glucuronide (EtG) and ethyl palmitate (EtPa) are frequently requested by local authorities, solicitors, or private individuals to assess long-term chronic excessive alcohol consumption. In this paper, we present a validation process aimed at developing sensitive methods for detecting EtG and EtPa in hair samples. EtG was extracted by overnight sonication in water followed by sample clean-up using solid phase extraction (SPE) and analysis by liquid chromatography–tandem mass spectrometry (LC-MS/MS). EtPa was extracted using a simple ultrasonication extraction followed by analysis using gas chromatography–tandem mass spectrometry (GC-MS/MS). The analytical method was validated by assessing linearity, precision, accuracy, recovery, sensitivity, and selectivity. Both EtG and EtPa methods obtained a coefficient of determination (r2) above 0.999 across concentration ranges of 4, 8, 16, 24, 48, and 96 pg/mg and 120, 240, 360, 480, 600, and 720 pg/mg. Extraction recoveries were both close to 100% with stable retention times and proven sensitivity and selectivity. These methods were validated according to the standards set by the United Kingdom Accreditation Service (UKAS) Lab51 and ISO 17025. Full article

(This article belongs to the Section Analytical Chemistry)

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22 pages, 2704 KiB

Open AccessArticle

Thermal Interaction Mechanisms of Ammonium Perchlorate and Ammonia Borane

by Yunlong Zhang, Rui Pu, Shaoli Chen and Qilong Yan

Molecules 2025, 30(13), 2680; https://doi.org/10.3390/molecules30132680 - 20 Jun 2025

Abstract

Ammonia borane (AB), with a theoretical hydrogen content of 19.6 wt%, is constrained by its low crystalline density (0.758 g/cm³) and poor thermal stability (decomposing at 100 °C). In this study, AB/ammonium perchlorate (AP) composites were synthesized via freeze-drying at a [...] Read more.

Ammonia borane (AB), with a theoretical hydrogen content of 19.6 wt%, is constrained by its low crystalline density (0.758 g/cm³) and poor thermal stability (decomposing at 100 °C). In this study, AB/ammonium perchlorate (AP) composites were synthesized via freeze-drying at a 1:1 molar ratio. The integration of AP introduced intermolecular interactions that suppressed AB decomposition, increasing the onset temperature by 80 °C. Subsequent vacuum calcination at 100 °C for 2 h formed oxygen/fuel-integrated ammonium perchlorate borane (APB), which achieved decomposition temperatures exceeding 350 °C. The proposed mechanism involved AB decomposing into borazine and BN polymers at 100 °C, which then NH₃BH₂⁺/ClO₄⁻ combined to form APB. At 350 °C, APB underwent the following redox reactions: 4NH₃BH₂ClO₄ → N₂↑ + 4HCl↑ + 2B₂O₃ + N₂O↑ + O₂↑ + 7H₂O↑ + H₂↑, while residual AP decomposed. The composite exhibited improved density (1.66 g/cm³) and generated H₂, N₂, O_2, and HCl, demonstrating potential for hydrogen storage. Additionally, safety was enhanced by the suppression of AB’s exothermic decomposition (100–200 °C). APB, with its high energy density and thermal stability, was identified as a promising high-energy additive for high-burning-rate propellants. Full article

(This article belongs to the Special Issue Molecular Design and Synthesis of Novel Energetic Compounds)

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20 pages, 1371 KiB

Open AccessArticle

Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein

by Chen Chen, Zhengfu Zhang, Qiao Zheng, Yingshun Zhou and Shujun Zhang

Molecules 2025, 30(13), 2679; https://doi.org/10.3390/molecules30132679 - 20 Jun 2025

Abstract

Severe acute respiratory syndrome coronavirus 2 has undergone several mutations since 2020, and novel variants continue to emerge to this day. The immune escape ability of the emerging mutants is enhanced and results in robust transmissibility. The neutralizing ability of the antibodies produced [...] Read more.

Severe acute respiratory syndrome coronavirus 2 has undergone several mutations since 2020, and novel variants continue to emerge to this day. The immune escape ability of the emerging mutants is enhanced and results in robust transmissibility. The neutralizing ability of the antibodies produced in the human body during previous infections is decreased against some of these mutants, which poses a severe challenge to the preventive and therapeutic effectiveness of vaccines and antibody drugs. The nucleocapsid protein is one of the main structural proteins of the coronavirus and plays an important role in the life cycle of the novel coronavirus. This protein is one of the key targets for drug development, and the first major step in drug development is to obtain pure nucleocapsid proteins. However, since nucleocapsid proteins have a nucleic acid-binding function and automatically undergo liquid–liquid phase separation and agglomeration, the purification of full-length nucleocapsids is challenging. In this context, a set of easy-to-operate processes was developed in this study for the purification of nucleocapsid proteins. Finally, a pure full-length nucleocapsid protein without nucleic acid contamination was obtained, which exhibited significantly enhanced accessibility for structural and functional virological studies, vaccine development, and related research applications. Further, the nucleic acid-binding domain of the nucleocapsid protein was targeted, and potential severe acute respiratory syndrome coronavirus 2 inhibitors were identified using virtual screening and biolayer interferometry technology. Notably, the eukaryotically expressed nucleocapsid protein demonstrated a significantly greater binding affinity for Light Green SF Yellowish (K_D = 119.7 nM) compared to that demonstrated by its prokaryotic counterpart (K_D = 19.9 × 10³ nM). The findings of this study suggest the importance of considering both protein source and post-translational modifications of the target proteins to be used in drug screening workflows. Therefore, this compound not only represents a novel therapeutic candidate for COVID-19 but also a critical tool for elucidating antiviral mechanisms. Full article

66 pages, 10841 KiB

Open AccessReview

The Role of Glycans in Human Immunity—A Sweet Code

by Igor Tvaroška

Molecules 2025, 30(13), 2678; https://doi.org/10.3390/molecules30132678 - 20 Jun 2025

Abstract

Glycans on the surface of all immune cells are the product of diverse post-translational modifications (glycosylation) that affect almost all proteins and possess enormous structural heterogeneity. Their bioinformational content is decoded by glycan-binding proteins (lectins, GBPs), such as C-type lectins, including selectins, galectins, [...] Read more.

Glycans on the surface of all immune cells are the product of diverse post-translational modifications (glycosylation) that affect almost all proteins and possess enormous structural heterogeneity. Their bioinformational content is decoded by glycan-binding proteins (lectins, GBPs), such as C-type lectins, including selectins, galectins, and Siglecs. Glycans located on the surface of immune cells are involved in many immunological processes through interactions with GBPs. Lectins recognize changes in the glycan epitopes; distinguish among host (self), microbial (non-self), and tumor (modified self) antigens; and consequently regulate immune responses. Understanding GBP–glycan interactions accelerates the development of glycan-targeted therapeutics in severe diseases, including inflammatory and autoimmune diseases and cancer. This review will discuss N- and O-glycosylations and glycosyltransferases involved in the biosynthesis of carbohydrate epitopes and address how interactions between glycan epitopes and GBPs are crucial in immune responses. The pivotal role of the glycan antigen tetrasaccharide sialyl Lewis x in mediating immune and tumor cell trafficking into the extravascular site will be discussed. Next, the role of glycans in modulating bacterial, fungal, viral, and parasitic infections and cancer will be surveyed. Finally, the role of glycosylation in antibodies and carbohydrate vaccines will be analyzed. Full article

(This article belongs to the Collection Advances in Glycosciences)

17 pages, 2816 KiB

Open AccessArticle

Photoluminescence Dependance of 2-Bromo-3-aminobenzo[de]anthracene-7-one on Solvent Polarity for Potential Applications in Color-Tunable Optoelectronics

by Emmanuel Karungani, Elena Kirilova, Liga Avotina, Aleksandrs Puckins, Sergejs Osipovs, Titus Ochodo, Mildred Airo and Francis Otieno

Molecules 2025, 30(13), 2677; https://doi.org/10.3390/molecules30132677 - 20 Jun 2025

Abstract

The novel benzanthrone derivative, 2-bromo-3-aminobenzo[de]anthracene-7-one (2-Br-3-NH₂BA), was synthesized and extensively characterized to investigate its photophysical behavior in various solvents. It was prepared through selective bromination of 3-aminobenzanthrone using N-bromosuccinimide in dimethylformamide at −20 °C. Featuring a donor–π–acceptor (D–π–A) structure, [...] Read more.

The novel benzanthrone derivative, 2-bromo-3-aminobenzo[de]anthracene-7-one (2-Br-3-NH₂BA), was synthesized and extensively characterized to investigate its photophysical behavior in various solvents. It was prepared through selective bromination of 3-aminobenzanthrone using N-bromosuccinimide in dimethylformamide at −20 °C. Featuring a donor–π–acceptor (D–π–A) structure, 2-Br-3-NH₂BA exhibits pronounced solvatochromism due to the intramolecular charge transfer (ICT) between the amino donor and the carbonyl acceptor groups. Optical measurements conducted in eight solvents of varying polarity revealed a significant bathochromic shift in both absorption and fluorescence emission, with emission maxima red-shifting by over 110 nm from non-polar to polar environments. Corresponding reductions in the optical band gap energies, as calculated from Tauc plots, further support solvent-induced electronic state modulation. Additionally, quantum yield analysis showed higher fluorescence efficiency in non-polar solvents, while polar solvents induced twisted intramolecular charge transfer (TICT), leading to emission quenching. These findings demonstrate the sensitivity of 2-Br-3-NH₂BA to environmental polarity, making it a promising candidate for color-tunable luminescent applications in optoelectronics and sensing. However, further studies in the solid state are required to validate its applicability in device architectures such as OLEDs. Full article

(This article belongs to the Special Issue Study on Synthesis and Photochemistry of Dyes)

19 pages, 1290 KiB

Open AccessArticle

Pharmacokinetics of Cannabidiol in Rat Brain Tissue After Single-Dose Administration of Different Formulations

by Zuzana Binova, Frantisek Benes, Marie Zlechovcova, Matej Maly, Petr Kastanek, Monika Cahova, Milena Stranska and Jana Hajslova

Molecules 2025, 30(13), 2676; https://doi.org/10.3390/molecules30132676 - 20 Jun 2025

Abstract

Cannabidiol (CBD), a phytocannabinoid commonly isolated from chemotype III Cannabis sativa plants, is known for its therapeutic potential. However, comprehensive information on its bioavailability is still lacking. The key objective of this study was to investigate the impact of specific formulations on CBD [...] Read more.

Cannabidiol (CBD), a phytocannabinoid commonly isolated from chemotype III Cannabis sativa plants, is known for its therapeutic potential. However, comprehensive information on its bioavailability is still lacking. The key objective of this study was to investigate the impact of specific formulations on CBD delivery to the site of action and, in particular, the brain of experimental animals. As brain tissue is an extremely complex matrix, a highly sensitive method employing liquid chromatography–tandem mass spectrometry (LC-MS/MS) had to be implemented. To make it applicable for multiple analytes, the method was validated for 17 other phytocannabinoids and selected metabolites. Using this method, a pharmacokinetic study was conducted on 200 brain samples collected from rats that had been administered various CBD formulations (carriers) via oral gavage. The peak concentration in brain occurred within 1–2 h; notably, the highest was reached with carriers containing triacylglycerols with the shortest fatty acid chains (caprylic/capric). In addition to the parent compound, 7-hydroxy-cannabidiol and 7-carboxy-cannabidiol were detected, confirming rapid post-administration metabolism. Overall, this research enhances understanding of CBD distribution in the brain and underscores the impact of specific formulations on its bioavailability, offering insights into optimizing CBD-based therapies to be both effective and ‘patient-friendly’. Full article

(This article belongs to the Special Issue Recent Advances in Cannabis and Hemp Research)

15 pages, 3493 KiB

Open AccessArticle

A Pathway for Sugar Production from Agricultural Waste Catalyzed by Sulfonated Magnetic Carbon Microspheres

by Maoru Xu, Yanfeng Duan, Hongfu Li, Shoulin He, Xingyu Zi, Yanting Zhao, Cheng Jiao and Xiaoyun Li

Molecules 2025, 30(13), 2675; https://doi.org/10.3390/molecules30132675 - 20 Jun 2025

Abstract

Lignocellulose is an important renewable biomass resource. However, at present, there is a lack of efficient and environmentally friendly catalytic systems that can selectively convert lignocellulose components into high-value sugars, and the value realization of agricultural waste (such as straw) remains challenging. Carbon-based [...] Read more.

Lignocellulose is an important renewable biomass resource. However, at present, there is a lack of efficient and environmentally friendly catalytic systems that can selectively convert lignocellulose components into high-value sugars, and the value realization of agricultural waste (such as straw) remains challenging. Carbon-based solid acids are used in the valorization of biomass due to their simple preparation and excellent catalytic performance. In this study, the magnetic carbon microspheres catalyst was prepared using concentrated sulfuric acid and hydroxyethyl sulfonic acid as sulfonating agents. Two sulfonation catalysts were applied to the hydrolysis of typical agricultural waste (rice straw). The performance of catalyst conversion to reducing sugar was compared, and the glucose yield was lower than 30%. The sulfonation catalyst of hydroxyethyl sulfonic acid obtained a higher yield of pentose (76.67%) than that of concentrated sulfuric acid (74.25%) in 110 min. The optimal reaction conditions were found: substrate was 0.04 g straw, catalyst was 0.04 g, H₂O/γ-valerolactone ratio was 8:2 in the solvent, and the reaction time was 110 min at 140 °C. Under these conditions, the sulfonation properties of hydroxyethyl sulfonic acid as a green sulfonating agent are similar to those of concentrated sulfuric acid. Its excellent catalytic performance is attributed to the medium B/L acid density ratio on the catalyst surface. In addition, the prepared catalyst can be effectively separated from the reaction residue in the catalytic system. This work provides a green catalytic system for the high-value utilization of agricultural waste from renewable carbon sources. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis for Sustainability and Carbon-Neutrality)

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16 pages, 712 KiB

Open AccessArticle

Catalytic Innovations in the Aza-Michael Reaction: An Experimental Benchmarking Focused on Sustainable Approaches

by Silvia Izquierdo, Carlos J. Durán-Valle, Pedro Cintas and Ignacio M. López-Coca

Molecules 2025, 30(13), 2674; https://doi.org/10.3390/molecules30132674 - 20 Jun 2025

Abstract

This study explores a series of eco-compatible, safe, inexpensive, and recyclable catalysts for the aza-Michael reaction, an essential transformation for constructing C-N bonds. In particular, we focus on hydrothermal carbons (HCB and HCC) prepared from chestnut cupule waste under mild, aqueous conditions, offering [...] Read more.

This study explores a series of eco-compatible, safe, inexpensive, and recyclable catalysts for the aza-Michael reaction, an essential transformation for constructing C-N bonds. In particular, we focus on hydrothermal carbons (HCB and HCC) prepared from chestnut cupule waste under mild, aqueous conditions, offering a sustainable alternative to traditional pyrolytic methods. These carbonaceous solids, thoroughly characterized by physicochemical techniques, exhibit notable catalytic activity, completing aza-Michael reactions in as little as 5–30 min for various model substrates. Their performance was benchmarked against Montmorillonite K10, [Cho][Pro] ionic liquid, and K10+[Cho][Pro], with the latter combination and [Cho][Pro] alone giving the fastest conversions. For example, the reaction of benzylamine with acrylonitrile reached complete conversion (typically 95% yield) in five minutes using [Cho][Pro], K10+[Cho][Pro], or likewise with HCB and HCC. Although the reactions catalyzed by hydrothermal carbons did not outperform in general those using K10-[Cho][Pro] or [Cho][Pro], they proceeded rapidly and afforded good to excellent yields. Furthermore, the HCC catalyst demonstrated excellent recyclability, maintaining its activity and yield over at least five cycles. These findings underscore the potential of hydrothermal carbons as efficient green heterogeneous catalysts, combining high surface area, porosity, and reusability with strong catalytic performance and scalability, in alignment with the principles of the circular economy. Full article

(This article belongs to the Special Issue New Horizons in Heterogeneous Catalysts: From Design to Applications)

21 pages, 6033 KiB

Open AccessArticle

BOPAM’s Bright and Dark Excited States: Insight from Structural, Photophysical, and Quantum Chemical Investigations

by Kexin Yu, Thanh Chung Pham, Jianjun Huang, Yixuan Li, Luc Van Meervelt, Mark Van der Auweraer, Daniel Escudero and Wim Dehaen

Molecules 2025, 30(13), 2673; https://doi.org/10.3390/molecules30132673 - 20 Jun 2025

Abstract

BOPAM exhibits high fluorescence quantum yields, along with exceptional photostability, rendering it a promising platform for applications as fluorescence sensors. However, the development of BOPAM-based fluorophores with extended emission wavelengths remains limited, and the underlying mechanisms of fluorescence quenching via the population of [...] Read more.

BOPAM exhibits high fluorescence quantum yields, along with exceptional photostability, rendering it a promising platform for applications as fluorescence sensors. However, the development of BOPAM-based fluorophores with extended emission wavelengths remains limited, and the underlying mechanisms of fluorescence quenching via the population of dark twisted intramolecular charge transfer (¹TICT) excited states are not yet fully understood. To address these gaps, we synthesized a series of BOPAM derivatives by incorporating electron-donating groups at the boron atoms and the phenyl rings of the BOPAM core. The introduction of bromide, phenyl, and naphthyl groups preserved the intrinsic locally excited (¹LE) emission of BOPAM. In contrast, the incorporation of diphenylamine (BP-DA) and triphenylamine (BP-TA) moieties resulted in a red-shifted emission, attributed to an enhanced intramolecular charge transfer (ICT) process. Notably, in acetonitrile, BP-DA exhibited weak fluorescence originating from a ¹TICT state, which was populated via the S₂ → ¹TICT transition. Furthermore, the emission observed from BP-TA was associated with a higher-lying excited state, likely the initially populated S₂ state possessing a ¹LE character. These findings not only introduce novel red-emissive BOPAM-based fluorophores, but also offer valuable insights into the role of the S₂ state in governing fluorescence quenching mechanisms in BOPAM derivatives. Full article

(This article belongs to the Special Issue BODIPYs: State of the Art and Future Perspectives)

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