Chemistry

18 pages, 1419 KB

Open AccessArticle

Preparation of Dithiocarbamate and Carboxyl Co-Modified Chitosan and Its Adsorption of Heavy Metal Copper from Copper–Ammonia Wastewater

by Chaoyang He, Tingting Jiang, Langbo Yi and Wenyong Hu

Chemistry 2026, 8(2), 16; https://doi.org/10.3390/chemistry8020016 - 30 Jan 2026

Abstract

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 [...] Read more.

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 (Q_m) 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. Full article

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

15 pages, 615 KB

Open AccessArticle

Novel 1,4-Naphthoquinone-Zidovudine Hybrid: Design, Synthesis, and In Vitro Evaluation of Its Anti-Trypanosomatid and Cytotoxic Activities

by 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 and Marco Edilson Freire de Lima

Chemistry 2026, 8(2), 15; https://doi.org/10.3390/chemistry8020015 - 29 Jan 2026

Abstract

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 [...] Read more.

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. 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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35 pages, 2952 KB

Open AccessReview

Thermo-Catalytic Carbon Dioxide Hydrogenation to Ethanol

by Xianyu Meng, Ying Wang, Jie Li, Hongxing Wang, Chenglong Yu, Jia Guo, Zhuo Zhang, Qingli Qian and Buxing Han

Chemistry 2026, 8(2), 14; https://doi.org/10.3390/chemistry8020014 - 28 Jan 2026

Abstract

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 CO [...] Read more.

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. Full article

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

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22 pages, 2073 KB

Open AccessArticle

Development of Cocoa (Theobroma cacao L.) CCN-51 Microcapsules with Antioxidant and Antimicrobial Properties

by 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 and Carlos Alfredo Cedeño-Palacios

Chemistry 2026, 8(2), 13; https://doi.org/10.3390/chemistry8020013 - 26 Jan 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Chemistry of Natural Products and Biomolecules)

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12 pages, 545 KB

Open AccessArticle

Pd/C–H₂-Catalyzed One-Pot Aromatization–Deoxygenation of Dihydropyridinediones: A Green, Scalable Route to Alkyl Pyridines

by Susanta Mandal, Tushar Sharma Banstola, Dhan Maya Chettri, Kimron Protim Phukan and Biswajit Gopal Roy

Chemistry 2026, 8(2), 12; https://doi.org/10.3390/chemistry8020012 - 26 Jan 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Molecular Organics)

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14 pages, 3924 KB

Open AccessArticle

Nitrogen-Doped Carbon Dots as Fluorescent and Colorimetric Probes for Nitrite Detection

by Aikun Liu, Xu Liu, Zixuan Huang and Yanqing Ge

Chemistry 2026, 8(1), 11; https://doi.org/10.3390/chemistry8010011 - 20 Jan 2026

Abstract

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 [...] Read more.

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. Full article

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

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14 pages, 5308 KB

Open AccessCommentary

An Appraisal of the Understanding Pressure Effects on Structural, Optical, and Magnetic Properties of CsMnF₄ and Other 3dⁿ Compounds

by Fernando Rodríguez

Chemistry 2026, 8(1), 10; https://doi.org/10.3390/chemistry8010010 - 16 Jan 2026

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Section Inorganic and Solid State Chemistry)

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14 pages, 1542 KB

Open AccessArticle

Ultraviolet Absorption Spectra of Benzene and Chlorobenzene in Water-Ice Solutions at Temperatures Between 78 K and 273 K

by Suresh Sunuwar and Carlos E. Manzanares

Chemistry 2026, 8(1), 9; https://doi.org/10.3390/chemistry8010009 - 9 Jan 2026

Abstract

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 [...] Read more.

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 (¹A_1g) to the first excited level of symmetry (B_2u), denoted as ¹B_2u ← ¹A_1g, and the transition from the ground state to the second excited level of symmetry (¹B_1u), denoted as ¹B_1u ← ¹A_1g, 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. Full article

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

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32 pages, 2990 KB

Open AccessArticle

Unified Analytical Treatment of Molecular Energy Spectra and Thermodynamic Properties with the q-Deformed Tietz Model

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

Chemistry 2026, 8(1), 8; https://doi.org/10.3390/chemistry8010008 - 9 Jan 2026

Abstract

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 [...] Read more.

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. Full article

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11 pages, 1245 KB

Open AccessCommentary

Energetic Preferences in Cyclic π-Conjugated Systems: Aromaticity Localizes and Antiaromaticity Spreads

by Miquel Solà and Luigi Cavallo

Chemistry 2026, 8(1), 7; https://doi.org/10.3390/chemistry8010007 - 9 Jan 2026

Abstract

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 [...] Read more.

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. Full article

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

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16 pages, 5352 KB

Open AccessArticle

CIGS Electrodeposition from Diluted Electrolyte: Effect of Current Density and Pulse Timing on Deposition Quality and Film Properties

by Mahfouz Saeed

Chemistry 2026, 8(1), 6; https://doi.org/10.3390/chemistry8010006 - 8 Jan 2026

Abstract

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 [...] Read more.

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. Full article

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

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22 pages, 2280 KB

Open AccessArticle

Optimisation of Cotinine Extraction from Fingernails Using Response Surface Methodology for Fourier Transform Infrared Spectroscopy Analysis

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

Chemistry 2026, 8(1), 5; https://doi.org/10.3390/chemistry8010005 - 6 Jan 2026

Abstract

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. [...] Read more.

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. Full article

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22 pages, 6992 KB

Open AccessArticle

Photoinduced Geometric Isomerization of 1-Aryl-1,3-Butadienes: Influence of Substituent on Photoreactivity—Structural and Photochemical Insights

by Maria Antonietta Dettori, Davide Fabbri, Roberto Dallocchio, Nicola Culeddu, Maria Orecchioni and Paola Carta

Chemistry 2026, 8(1), 4; https://doi.org/10.3390/chemistry8010004 - 31 Dec 2025

Abstract

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, [...] Read more.

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. Full article

(This article belongs to the Section Photochemistry and Excited States)

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11 pages, 1712 KB

Open AccessCommunication

UV–Vis Spectra of Gold(III) Complexes with Different Halides, Hydroxide, and Ammonia According to TD-DFT Calculations

by Olga I. Logacheva, Oleg A. Pimenov and George A. Gamov

Chemistry 2026, 8(1), 3; https://doi.org/10.3390/chemistry8010003 - 29 Dec 2025

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Topic Theoretical, Quantum and Computational Chemistry—2nd Edition)

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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

Cited by 2

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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