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Chemistry

Chemistry is an international, peer-reviewed, open access journal on chemistry published bimonthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), CAPlus / SciFinder, and other databases.
Reliable service: rigorous peer review and professional production.
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 17.2 days after submission; acceptance to publication is undertaken in 2.6 days (median values for papers published in this journal in the second half of 2024).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Extra benefits: no space constraints, no color charges.

Impact Factor: 2.4 (2023); 5-Year Impact Factor: 2.4 (2023)

Imprint Information Journal Flyer Open Access ISSN: 2624-8549

Latest Articles

16 pages, 6576 KiB

Open AccessReview

m-Quinodimethane-Based Fused-Ring Diradicals with Singlet and Triplet Ground States

by Akihiro Shimizu

Chemistry 2025, 7(2), 40; https://doi.org/10.3390/chemistry7020040 - 13 Mar 2025

Diradicals have attracted the attention of chemists due to their unique electronic structures and properties originating from unpaired electrons. One of the fundamental motifs of diradicals is quinodimethane; p- and o-quinodimethanes are singlet Kekulé hydrocarbons, while m-quinodimethane is a triplet [...] Read more.

Diradicals have attracted the attention of chemists due to their unique electronic structures and properties originating from unpaired electrons. One of the fundamental motifs of diradicals is quinodimethane; p- and o-quinodimethanes are singlet Kekulé hydrocarbons, while m-quinodimethane is a triplet non-Kekulé hydrocarbon. Most of the hydrocarbon diradicals studied to date have been limited to p- and o-quinodimethane-based non-fused-ring and fused-ring open-shell singlet diradicals and m-quinodimethane-based non-fused-ring triplet diradicals. In this account, studies on m-quinodimethane-based fused-ring diradicals, including an open-shell singlet Kekulé hydrocarbon, an open-shell singlet zwitterion, non-Kekulé hydrocarbon-based triplet diradical and diradical cation, and a triplet Kekulé hydrocarbon, are summarized. They are designed, successfully synthesized, and isolated as crystals, and their fundamental electronic structures and properties have been elucidated by optical, electrochemical, and magnetic measurements, together with DFT calculations. A series of studies showed that controlling the interaction between the two unpaired electrons of m-quinodimethane through an appropriate molecular design would produce polycyclic diradicals with various open-shell singlet diradical characters and the energy differences between singlet and triplet states. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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10 pages, 2571 KiB

Open AccessArticle

2,4,6-Trichlorophenyl-Substituted [3]Triangulene with Enhanced Stability

by Yiming Yang, Peipei Liu, Xiaoli Zhao and Xueliang Shi

Chemistry 2025, 7(2), 39; https://doi.org/10.3390/chemistry7020039 - 13 Mar 2025

Triangulene, also known as Clar’s hydrocarbon, has been sought after by chemists for more than 70 years but with limited success. Herein, we report an oxidative dehydrogenation method to synthesize two kinetically blocked [3]triangulene derivatives TRI-1 (reported) and TRI-2 (newly synthesized), in which [...] Read more.

Triangulene, also known as Clar’s hydrocarbon, has been sought after by chemists for more than 70 years but with limited success. Herein, we report an oxidative dehydrogenation method to synthesize two kinetically blocked [3]triangulene derivatives TRI-1 (reported) and TRI-2 (newly synthesized), in which the three most reactive sites are substituted by bulky mesityl groups and electron-withdrawing 2,4,6-trichlorophenyl groups, and meanwhile, three vertices of triangulene are substituted by tert-butyl groups. Interestingly, the dihydro-triangulene core possesses two isomers well characterized by UV-vis, NMR spectroscopy, and X-ray crystallographic analysis, which is interestingly substituent-dependent. The newly synthesized TRI-2 is isolated in crystalline form, and X-ray crystallographic analysis reveals that the aryl substituents are nearly perpendicular to the triangulene plane and thus cause little perturbation of the electronic properties of the triangulene. Notably, 2,4,6-trichlorophenyl-substituted TRI-2 exhibits enhanced stability compared to the reported mesityl-substituted TRI-1, e.g., TRI-2 is stable for months in a crystalline state under a nitrogen atmosphere, and TRI-2 in a solution state is also more persistent than TRI-1 (half-life for TRI-1 ≈ 18 h vs. TRI-2 ≈ 132 h). This achievement will facilitate the design and synthesis of stable triangulene dimers and oligomers with higher spin multiplicity. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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72 pages, 3505 KiB

Open AccessReview

Quantum Mechanical Approaches to Strongly Correlated Electron Systems: Structure, Bonding, and Properties of Diradicals, Triradicals, and Polyradicals

by Satoru Yamada, Isamu Shigemoto, Takashi Kawakami, Hiroshi Isobe, Mitsuo Shoji, Koichi Miyagawa and Kizashi Yamaguchi

Chemistry 2025, 7(2), 38; https://doi.org/10.3390/chemistry7020038 - 12 Mar 2025

The structure, bonding, and properties of diradicals, triradicals, and polyradicals have been investigated using broken symmetry (BS) molecular orbital (MO) and BS density functional theory (DFT) methods, which are regarded as the first steps in the mean-field approach toward strongly correlated electron systems [...] Read more.

The structure, bonding, and properties of diradicals, triradicals, and polyradicals have been investigated using broken symmetry (BS) molecular orbital (MO) and BS density functional theory (DFT) methods, which are regarded as the first steps in the mean-field approach toward strongly correlated electron systems (SCES). The natural orbital (NO) analyses of the BS MO and BS DFT solutions were performed to elucidate the natural orbitals of their occupation numbers, which are used for derivations of the diradical character (y) and several chemical indices for the open-shell molecules under investigation. These chemical indices are also obtained using SCES, the next theoretical step, which uses symmetry-recovered resonating BS (RBS) and multi-determinant methods such as multi-reference (MR) configuration interaction (CI) and MR-coupled cluster (CC) methods that employ the NOs generated in the first step. The nonlinear optical response properties of organic open-shell species were theoretically investigated with several procedures, such as MR CI (CC), the numerical Liouville, and Monte Carlo wavefunction methods, as the third step to SCES. The second-order hyperpolarizability (γ) of diradicals such as a phenalenyl radical dimer were mainly investigated in relation to the generation of quantum squeezed lights, which are used for the construction of the quantum entangled states for quantum optical devices such as quantum sensing and quantum computation. Basic quantum mechanical concepts, such as the Pegg–Barnett quantum phase operator, were also revisited in relation to the design and chemical synthesis of stable diradicals and polyradicals such as optical quantum molecular materials and future molecular qubits materials. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

13 pages, 4415 KiB

Open AccessArticle

A Stable π-Expanded o-Quinodimethane via the Photochemical Dearomative Cycloaddition of Corannulene with an Isolable Dialkylsilylene

by Shintaro Ishida, Maiko Mori, Shunya Honda and Takeaki Iwamoto

Chemistry 2025, 7(2), 37; https://doi.org/10.3390/chemistry7020037 - 11 Mar 2025

A stable π-expanded o-quinodimethane derivative (2) was synthesized by photochemical dearomative cycloaddition of corannulene with an isolable dialkylsilylene (1) and isolated as a dark blue solid. Compound 2 adopts a very flat bowl shape in contrast to parent [...] Read more.

A stable π-expanded o-quinodimethane derivative (2) was synthesized by photochemical dearomative cycloaddition of corannulene with an isolable dialkylsilylene (1) and isolated as a dark blue solid. Compound 2 adopts a very flat bowl shape in contrast to parent corannulene. Structural and spectroscopic characteristics, redox properties, and computational study suggest that 2 has a small but significant diradical character (y₀ = 0.11). One-electron reduction of 2 provides the corresponding radical anion as an isolable salt. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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27 pages, 7757 KiB

Open AccessArticle

New Derivatives of Oleanolic Acid: Semi-Synthesis and Evaluation of Their Anti-15-LOX, Anti-α-Glucosidase and Anticancer Activities and Molecular Docking Studies

by Nahla Triaa, Salma Jlizi, Mansour Znati, Hichem Ben Jannet and Jalloul Bouajila

Chemistry 2025, 7(2), 36; https://doi.org/10.3390/chemistry7020036 - 7 Mar 2025

A novel series of oleanolic acid (OA, 1) derivatives incorporating phenolic and coumarin moieties were synthesized. This acid was extracted from olive pomace (Olea europaea L.) using an ultrasound-assisted method. The structures of these novel derivatives of OA were [...] Read more.

A novel series of oleanolic acid (OA, 1) derivatives incorporating phenolic and coumarin moieties were synthesized. This acid was extracted from olive pomace (Olea europaea L.) using an ultrasound-assisted method. The structures of these novel derivatives of OA were characterized through the utilization of ¹H-NMR, ¹³C-NMR and ESI-HRMS analyses. An evaluation of some biological activities of the prepared derivatives was conducted. The evaluation focused principally on the capacity of these structures to inhibit 15-lipoxygenase and α-glucosidase, as well as their anticancer properties when tested against tumour cell lines (HCT-116 and LS-174T) and a non-tumour cell line (HEK-293). In terms of their cytotoxic activity, the majority of the compounds exhibited notable inhibitory effects compared to the starting molecule, OA. Derivatives 4d, 4k and 4m exhibited particularly strong inhibitory effects against the HCT-116 cell line, with IC₅₀ values of 38.5, 39.3, 40.0 µM, respectively. Derivatives 4l, 4e and 5d demonstrated the most effective inhibition against the LS-174T cell line, with IC₅₀ values of 44.0, 44.3, 38.0 µM, respectively. However, compound 2a was the most effective, exhibiting the most potent inhibition of 15-lipoxygenase and α-glucosidase, with IC₅₀ values of 52.4 and 59.5 µM, respectively. Furthermore, molecular docking studies supported in vitro cytotoxic activity, revealing that the most potent compounds exhibited low binding energies and interacted effectively within the EGFR enzyme’s active pocket (PDB: 1M17). These findings highlight the potential of these derivatives as anticancer agents and enzymatic inhibitors, warranting further investigation. Full article

(This article belongs to the Section Medicinal Chemistry)

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16 pages, 981 KiB

Open AccessArticle

Computational Models for Analyzing the Thermodynamic Properties of Linear Triatomic Molecules

by Edwin S. Eyube, Abubakar D. Ahmed, Clement A. Onate, Ekwevugbe Omugbe, Etido P. Inyang, Sanda Amasuwa and Ezekiel K. Makama

Chemistry 2025, 7(2), 35; https://doi.org/10.3390/chemistry7020035 - 5 Mar 2025

This study presents analytical models for simulating the thermal properties of linear triatomic systems, using the modified Rosen–Morse oscillator and harmonic oscillator potential to represent vibrational modes. The models employ existing partition functions to derive the thermodynamic functions for the symmetric, asymmetric, and [...] Read more.

This study presents analytical models for simulating the thermal properties of linear triatomic systems, using the modified Rosen–Morse oscillator and harmonic oscillator potential to represent vibrational modes. The models employ existing partition functions to derive the thermodynamic functions for the symmetric, asymmetric, and 2-fold degenerate bending modes. These thermodynamic functions are applied to gaseous triatomic molecules such as BO₂, HCN, N₃, and Si₂N. The results demonstrate high accuracy, with mean percentage absolute deviations (MPAD) of less than 0.17% for molar entropy and Gibbs free energy. For enthalpy and heat capacity, MPAD values are below 2% compared to National Institute of Standards and Technology (NIST) data. The findings are in strong agreement with the existing literature on gaseous triatomic molecules, confirming the reliability of the proposed models. Full article

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

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19 pages, 3023 KiB

Open AccessArticle

Anti-Orthopoxvirus Activity of Amantadine and Rimantadine Derivatives—In Vitro Testing and Molecular Modeling

by Ivan A. Moskalev, Ekaterina A. Akishina, Evgenij A. Dikusar, Olga I. Yarovaya, Sophia S. Borisevich, Edward M. Khamitov, Alexey Yu. Fedorov, Sergey G. Arkhipov, Nikolay I. Bormotov, Olga A. Serova, Larisa N. Shishkina, Vladimir. I. Potkin and Nariman F. Salakhutdinov

Chemistry 2025, 7(2), 34; https://doi.org/10.3390/chemistry7020034 - 1 Mar 2025

In 2022, the number of mpox cases spiked worldwide, leading to a surge in scientific research on members of the Orthopoxvirus genus and the discovery of new compounds exhibiting anti-orthopoxvirus activity. This work is devoted to the synthesis of compounds containing an adamantane [...] Read more.

In 2022, the number of mpox cases spiked worldwide, leading to a surge in scientific research on members of the Orthopoxvirus genus and the discovery of new compounds exhibiting anti-orthopoxvirus activity. This work is devoted to the synthesis of compounds containing an adamantane fragment and the evaluation of their activity against the vaccinia virus, offering a possible mechanism of the antiviral action of the synthesized agents. Among all the studied adamantane derivatives, three compounds (2, 4, and 12) were found to demonstrate the highest antiviral activity, with the most promising compound 2 (N-(adamantan-1-yl)isonicotinamide) having the lowest toxicity level with a selectivity index (SI) of 115. The pharmacophoric profiles of these compounds are similar to the pharmacophoric profile of tecovirimat, an inhibitor of the membrane viral protein p37. Analysis of the results of molecular modeling suggests that the investigated compounds can inhibit the vaccinia virus by suppressing the phospholipase activity of membrane viral protein p37. Full article

(This article belongs to the Topic Enzymes and Enzyme Inhibitors in Drug Research)

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19 pages, 4738 KiB

Open AccessArticle

An Extensive Study of the Production of Hydrogen by Cellulose and Lignin Pyrolysis Using Rhenium-Based Catalysts

by Mizraim Guillermo Granados-Fitch, Juan Manuel Quintana-Melgoza, Erick Adrian Juarez-Arellano and Miguel Avalos-Borja

Chemistry 2025, 7(2), 33; https://doi.org/10.3390/chemistry7020033 - 1 Mar 2025

The use of rhenium-based catalysts (Re₂C, Re₃B, ReB₂, and ReS₂) obtained by mechanosynthesis in the pyrolysis of cellulose and lignin from 500 to 800 °C using 10 and 20 wt.% of catalysts is reported. The [...] Read more.

The use of rhenium-based catalysts (Re₂C, Re₃B, ReB₂, and ReS₂) obtained by mechanosynthesis in the pyrolysis of cellulose and lignin from 500 to 800 °C using 10 and 20 wt.% of catalysts is reported. The mechanosynthesis of ReS₂ has been reported for the first time. The catalytic pyrolysis of cellulose resulted in maximum H₂ production at 800 °C and 10 wt.% catalyst, with 44% H₂ yield using a Re₃B catalyst. In contrast, lignin catalytic pyrolysis also showed maximum production under the same conditions, with an 86.1% H₂ yield using the NiO/SiO₂ catalyst; however, the catalyst did not drastically enhance H₂ production. H₂ formation by cellulose pyrolysis is a thermocatalytic process, whereas lignin pyrolysis is an entirely thermic process. A reaction mechanism was proposed to explain the H₂ formation by both catalytic cellulose and lignin pyrolysis. Full article

(This article belongs to the Section Catalysis)

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10 pages, 3623 KiB

Open AccessArticle

Solid–Liquid Phase Transition-Induced Magnetic Property Changes in Tetrakis(ethylthio)tetrathiafulvalene Radical Cation Salt

by Toshihiro Sakai, Soichiro Kawamorita, Takeshi Naota and Shuichi Suzuki

Chemistry 2025, 7(2), 32; https://doi.org/10.3390/chemistry7020032 - 1 Mar 2025

We discovered that the radical cation salt [1^•+][NTf₂⁻], composed of tetrakis(ethylthio)tetrathiafulvalene radical cation and bis(N-trifluoromethanesulfonyl)imide ion, exhibits significant changes in its magnetic properties during a solid–liquid phase transition. Single-crystal structure analysis revealed that the radical [...] Read more.

We discovered that the radical cation salt [1^•+][NTf₂⁻], composed of tetrakis(ethylthio)tetrathiafulvalene radical cation and bis(N-trifluoromethanesulfonyl)imide ion, exhibits significant changes in its magnetic properties during a solid–liquid phase transition. Single-crystal structure analysis revealed that the radical cation salt [1^•+][NTf₂⁻] forms an associated structure called a π-dimer in the crystalline phase. The extremely weak ESR signal in the crystalline state indicates strong antiferromagnetic interactions between unpaired electrons within the π-dimer. Upon heating, the crystalline phase transitions into a liquid state without decomposition at 144 °C (417 K). The ESR signals in the liquid state are significantly stronger than those in the solid state, suggesting the formation of a paramagnetic state with weak interactions between radical cations. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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14 pages, 1995 KiB

Open AccessArticle

Computational Design and Synthesis of Phthalimide Derivatives as TGF-β Pathway Inhibitors for Cancer Therapeutics

by Héctor M. Heras-Martínez, Blanca Sánchez-Ramírez, Linda-Lucila Landeros-Martínez, Víctor H. Ramos-Sánchez, Alejandro A. Camacho-Dávila, Kostiantyn O. Marichev, Alejandro Bugarin and David Chávez-Flores

Chemistry 2025, 7(2), 31; https://doi.org/10.3390/chemistry7020031 - 26 Feb 2025

Background: This study investigates the synthesis and pharmacological potential of N-substituted isoindoline-1,3-dione (phthalimide) derivatives. Using the M06 meta-GGA hybrid functional with a polarized 6-311G(d,p) basis set, computational evaluations assessed their impact on apoptosis modulation in colon cancer cells. Molecular docking studies targeted [...] Read more.

Background: This study investigates the synthesis and pharmacological potential of N-substituted isoindoline-1,3-dione (phthalimide) derivatives. Using the M06 meta-GGA hybrid functional with a polarized 6-311G(d,p) basis set, computational evaluations assessed their impact on apoptosis modulation in colon cancer cells. Molecular docking studies targeted the TGF-β protein (PDB: 1RW8) at the ALK5 binding site. On this study fourteen molecules were evaluated (P1–P14) and six (P1, P3, P4, P5, P7, and P13) demonstrated promising binding values. Methods: from the fourteen studied compounds five compounds (P2, P4, P7, P10, and P11) were successfully synthesized and fully characterized. The reactions were monitored via TLC and HPLC confirming high-purity compounds. Functional groups were identified through FTIR and structural characterization was supported by NMR analyses. Results: Density functional theory calculations and docking simulations allowed to classified the compounds as potential ALK5 inhibitors. Synthesized derivatives were developed in yields from 85 to 99% and showed better binding affinities than Capecitabine (−6.95 kcal/mol) used as control compound, with P7 (5-hydroxy-4-oxo-2-phenyl-4H-chromen-7-yl 2-(1,3-dioxoisoindolin-2-yl) acetate) leading the group with a binding energy of −12.28 kcal/mol. Other synthesized compounds also exhibited significant affinities: P4 (−11.42 kcal/mol), P10 (−8.99 kcal/mol), P11 (−7.50 kcal/mol), and P2 (−7.22 kcal/mol). Conclusions: Integrating computational insights with experimental validation highlights the therapeutic potential of phthalimide derivatives, particularly P7. The study underscores a rigorous approach to identifying promising candidates for anticancer therapeutics, warranting further exploration. Full article

(This article belongs to the Special Issue Cutting-Edge Studies of Computational Approaches in Drug Discovery)

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16 pages, 16198 KiB

Open AccessArticle

Effects of Substituent and Scaffold Changes on the Inhibition of Human P5C Reductase by Phenyl-Substituted Aminomethylene Bisphosphonates

by Giuseppe Forlani

Chemistry 2025, 7(2), 30; https://doi.org/10.3390/chemistry7020030 - 25 Feb 2025

Being overexpressed in many cancer types and related to tumor invasiveness, the activity of P5C reductase represents a promising target for cancer therapy, yet no effective inhibitors have been identified so far. Several phenyl-substituted aminomethylenebisphosphonic acids had been found to inhibit the plant [...] Read more.

Being overexpressed in many cancer types and related to tumor invasiveness, the activity of P5C reductase represents a promising target for cancer therapy, yet no effective inhibitors have been identified so far. Several phenyl-substituted aminomethylenebisphosphonic acids had been found to inhibit the plant enzyme in the micro- to millimolar range. The two most active compounds were previously shown to be remarkably active against human P5C reductase (PYCR1, gene ID 5831). To investigate their structure–activity relationships, the human enzyme was heterogously expressed in E. coli, affinity purified and assayed in the presence of increasing concentrations of various aminobisphosphonates differing in substituents on the phenyl ring, using either NADH or NADPH as the electron donor. Some analogues, namely aminoethylenebisphosphonates, hydroxybisphosphonates, aminophosphonates and hydroxyphosphonates, were also evaluated. Results allowed to define the chemical features required for effective inhibition. The aminobisphosphonic moiety was found essential for activity, which was enhanced by the presence of electron-withdrawing substituents on the phenyl ring, provided that an optimal steric hindrance is not exceeded. These results could open up new perspectives on the synthesis of effective inhibitors of human P5C reductase to be used in chemotherapy. Full article

(This article belongs to the Section Medicinal Chemistry)

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36 pages, 4825 KiB

Open AccessReview

Packed Bed Microreactors for Sustainable Chemistry and Process Development

by Lu Zhang and Jun Yue

Chemistry 2025, 7(2), 29; https://doi.org/10.3390/chemistry7020029 - 24 Feb 2025

Microreactor technology is seen as a promising approach to achieve green and sustainable synthesis in chemical fields because of the significant process intensification and fine control over reaction parameters caused by the miniaturization of reactor scale. The incorporation of solid catalysts as a [...] Read more.

Microreactor technology is seen as a promising approach to achieve green and sustainable synthesis in chemical fields because of the significant process intensification and fine control over reaction parameters caused by the miniaturization of reactor scale. The incorporation of solid catalysts as a packed bed in microreactors opens numerous opportunities for the efficient heterogeneous catalysis that plays a pivotal role in many industrially relevant chemical processes. In this review, the recent development in the use of packed bed microreactors as a versatile research tool and intensified production unit will be highlighted in the application areas including the synthesis of valuable chemicals and fuels, high-throughput catalyst screening, and kinetic/chemistry investigation. Selected reaction examples involving different reactant phases and catalyst categories will be particularly discussed, with an emphasis on the reactor performance in relation to the fundamental chemistry and engineering principles under microflow. In the end, future challenges and the outlook of packed bed microreactors for sustainable chemistry and process development will be provided. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Professor George Whitesides on the Occasion of His 85th Birthday Anniversary)

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16 pages, 3603 KiB

Open AccessArticle

Synthesis of Terbenzo- and Tetrabenzoolympicenyl Radicals and Their Cations

by Zewen Guo, Xiaoqi Tian and Zhe Sun

Chemistry 2025, 7(2), 28; https://doi.org/10.3390/chemistry7020028 - 24 Feb 2025

The synthesis of two polycyclic aromatic hydrocarbon (PAH) monoradicals, terbenzoolympicenyl radical (BOR1) and tetrabenzoolympicenyl radical (BOR2), is reported. One-electron oxidation of both BOR1 and BOR2 yielded stable cationic species BOR1+ and BOR2+, whose structures were unambiguously characterized using [...] Read more.

The synthesis of two polycyclic aromatic hydrocarbon (PAH) monoradicals, terbenzoolympicenyl radical (BOR1) and tetrabenzoolympicenyl radical (BOR2), is reported. One-electron oxidation of both BOR1 and BOR2 yielded stable cationic species BOR1+ and BOR2+, whose structures were unambiguously characterized using 2D nuclear magnetic resonance (NMR) spectroscopy. The physical properties of BOR1 and BOR2 were investigated by means of electron paramagnetic resonance (EPR), UV-vis-NIR, cyclic voltammetry (CV), and density functional theory (DFT) calculations. BOR1+ and BOR2+ exhibited intense near-infrared (NIR) absorption, which may be of potential use in the biological fields. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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9 pages, 2847 KiB

Open AccessCommunication

Crystalline Diradical Dianions and Radical Anions of Indenofluorenediones

by Xue Dong, Tao Wang, Yu Zhao, Quanchun Sun, Shuxuan Tang, Yue Zhao and Xinping Wang

Chemistry 2025, 7(1), 27; https://doi.org/10.3390/chemistry7010027 - 19 Feb 2025

Fluorenone derivatives represent promising candidates for electron-transport materials in organic electronic devices. Given that anionic species serve as electron-transfer carriers in electron-transport materials, it is highly desirable to isolate and characterize the radical anions and dianions of indenofluorened derivatives (IFO). In this work, [...] Read more.

Fluorenone derivatives represent promising candidates for electron-transport materials in organic electronic devices. Given that anionic species serve as electron-transfer carriers in electron-transport materials, it is highly desirable to isolate and characterize the radical anions and dianions of indenofluorened derivatives (IFO). In this work, the reduction of three indenofluorenedione derivatives (IFO, 1, 2 and 3) with potassium resulted in three radical anion salts (1K[(crypt-222)], 2K[(crypt-222)] and 3K) and one dianion salt (2[K(crypt-222)]₂). Single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy reveal that 1K[(crypt-222)] and 2K[(crypt-222)] have a full delocalization of the unpaired electron which is supported by calculated spin density distributions. We demonstrate that the polarization of electron spin in 3K is induced by potassium ion coordination through single-crystal X-ray structure analysis and DFT calculations, suggesting the electrostatic effect by potassium ion has a significant influence on the spin density modulation. Superconducting quantum interference device (SQUID) measurements and DFT calculations show that 2[K(crypt-222)]₂ has an open-shell singlet base with a large singlet-triplet energy gap (ΔE_os-t = −7.40 kcal mol⁻¹) so that the excited triplet state is not accessible at room temperature. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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19 pages, 11004 KiB

Open AccessArticle

The Influence of Electron Beam Irradiation on the Performance of Hydrogenation Catalysts Containing Co and Carboneous Particles on Silica

by Mykola I. Arabadzhy, Vyacheslav P. Pashkevych, Olena O. Pariiska, Oleksiy V. Melnychenko, Volodymyr V. Buryanov, Vladyslav V. Subotin, Bohdan V. Vashchenko, Eugeniy M. Ostapchuk, Andriy I. Frolov, Konstantin S. Gavrilenko, Serhiy V. Ryabukhin, Dmytro M. Volochnyuk and Sergey V. Kolotilov

Chemistry 2025, 7(1), 26; https://doi.org/10.3390/chemistry7010026 - 19 Feb 2025

This study was aimed at elucidating the role of the carboneous component in Co–carbon-containing catalysts for the hydrogenation of organic compounds. A Co-C/SiO₂ catalyst was synthesized via pyrolysis of a Co(II) complex with 1,2-diaminobenzene on silica and subsequently irradiated with 2.3 MeV [...] Read more.

This study was aimed at elucidating the role of the carboneous component in Co–carbon-containing catalysts for the hydrogenation of organic compounds. A Co-C/SiO₂ catalyst was synthesized via pyrolysis of a Co(II) complex with 1,2-diaminobenzene on silica and subsequently irradiated with 2.3 MeV electrons, producing Co-C/SiO₂*. A comprehensive characterization using XRD, TEM, IR, and Raman spectroscopy indicated minimal structural changes in the cobalt nanoparticles and carboneous materials. However, the Raman analysis revealed a slight decrease in the structural defect content in the carboneous component upon irradiation, which could occur due to defect healing. The catalytic tests, including the hydrogenation of 26 compounds, demonstrated an enhanced performance of the irradiated catalyst in 17 cases. This performance improvement was attributed to a modification of the carboneous material. It could be concluded that the carboneous components in Co-C composites contributed to their catalytic performance, probably by modifying the electronic structure of Co nanoparticles. In turn, the results provide arguments against the supposition that hydrogenation occurs on the structural defects of the carboneous material. Full article

(This article belongs to the Section Catalysis)

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17 pages, 2267 KiB

Open AccessArticle

Simulating Analyte Extraction via Sorption in Powdered and Lyophilized Pharmaceutical Products Using Butyl Rubbers

by Nikolaos Kritikos, Anna Bletsou, Constantinos Kousoulos and Yannis Dotsikas

Chemistry 2025, 7(1), 25; https://doi.org/10.3390/chemistry7010025 - 18 Feb 2025

A novel extraction method based on solid-to-solid interactions has been developed to investigate the acquisition of contaminants from butyl rubber materials, with potential applications in the pharmaceutical industry. The extraction medium used is silica gel—a cost-effective, non-toxic, heat-resistant, and chemically inert material that [...] Read more.

A novel extraction method based on solid-to-solid interactions has been developed to investigate the acquisition of contaminants from butyl rubber materials, with potential applications in the pharmaceutical industry. The extraction medium used is silica gel—a cost-effective, non-toxic, heat-resistant, and chemically inert material that is easy to handle in laboratory settings. Silica gel also enables straightforward recovery of adsorbed species using standard laboratory solvents. This method effectively exhausts contaminants from typical rubber articles within a reasonable timeframe, even under ambient conditions, while preserving the integrity of the material. Unlike traditional destructive liquid-based extractions, this approach produces significantly cleaner chromatographic profiles. This study focuses on the primary analytes extracted from chlorobutyl rubber, including halogenated rubber volatile impurities (VOIs), and tracks their acquisition over the course of the experiment. The findings provide valuable insights into the diffusion-based process by which pharmaceutical powders acquire contaminants, spanning a wide range of volatility and lipophilicity. Full article

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18 pages, 1166 KiB

Open AccessArticle

Chemical and Biological Investigation of Ceiba chodatii Hassl. Flowers

by Engy Saadalah Ibrahem, John Refaat Fahim, Mamdouh Nabil Samy, Ahmed G. Darwish, Samar Yehia Desoukey, Mohamed Salah Kamel and Samir A. Ross

Chemistry 2025, 7(1), 24; https://doi.org/10.3390/chemistry7010024 - 12 Feb 2025

Ceiba (syn. Chorisia) trees have attracted multifaceted attention not only due to their ornamental and economic value but also for their remarkable metabolic diversity and therapeutic properties. In view of that, this work explores the chemical composition of Ceiba chodatii Hassl. and [...] Read more.

Ceiba (syn. Chorisia) trees have attracted multifaceted attention not only due to their ornamental and economic value but also for their remarkable metabolic diversity and therapeutic properties. In view of that, this work explores the chemical composition of Ceiba chodatii Hassl. and its biological potential. Overall, GC–MS-based analysis of the lipoidal constituents of C. chodatii flowers revealed the presence of diverse classes of metabolites that were dominated by long-chain aliphatic esters (77.016%), ketones (6.396%), aliphatic hydrocarbons (5.757%), fatty alcohols (3.718%), aromatic acid esters (2.794%), alkylamides (1.58%), aldehydes (1.035%), aromatic hydrocarbons (0.31%), and ethers (0.29%). In addition, repeated chromatographic fractionation of different fractions of the total alcoholic extract of the flowers afforded 13 metabolites of varied structural types, including fatty esters and alcohols, phytosterols, monoglycerides, furanoids, and flavonoid glycosides. Structures of the obtained compounds were determined by different spectroscopic techniques, such as 1H- and 13C-NMR, APT, DEPT, and EI–MS analyses. Noteworthily, a wide range of the metabolites identified herein using different analytical approaches were described for the first time in the plant species under study or in those belonging to the genus Ceiba. Finally, the total extract and different fractions of C. chodatii flowers as well as the isolated flavonoids showed weak anti-infective potential against a group of human pathogens at concentration ranges up to 200 and 20 µg/mL, respectively. In contrast, the total extract and different fractions of the flowers exerted mild to moderate anti-proliferative activities against MDA-MB-468 cells, with IC₅₀ in the range of 21.69–47.60 μg/mL. Full article

(This article belongs to the Section Biological and Natural Products)

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12 pages, 4907 KiB

Open AccessArticle

Brazilian Plume (Justicia carnea L.) Leaf Wine-Colored Extract for Natural Dyeing of Mordant-Functionalized Cellulosic Fabric: Color Strength, Coordinates, and Fastness

by Jamiu Mosebolatan Jabar, Olugbenga Oludayo Oluwasina, Odunayo Michael Agunloye, Afolabi Clement Akinmoladun, Olamide Abigael Akande, Elizabeth Toyin Ojo and Hannah Olubukola Olojuolawe

Chemistry 2025, 7(1), 23; https://doi.org/10.3390/chemistry7010023 - 8 Feb 2025

Increasing awareness of protecting the environment from chemically aided naive ecosystem degradation has encouraged the use of eco-friendly (biomass) materials in industrial production globally. This study investigated the application of a natural wine-colored extract from Brazilian plume (BP) leaf, obtained through a microwave-assisted [...] Read more.

Increasing awareness of protecting the environment from chemically aided naive ecosystem degradation has encouraged the use of eco-friendly (biomass) materials in industrial production globally. This study investigated the application of a natural wine-colored extract from Brazilian plume (BP) leaf, obtained through a microwave-assisted modern aqueous extraction technique, for toxic-free dyeing of mordant-functionalized cotton fabric. Dyeing of mordanted cotton fabric was optimized by varying dyeing parameters, such as dyeing contact time (10 to 90 min), pH (1 to 11), liquor ratio (1:5 to 1:30), and temperature (30 to 90 °C). UV-visible and Fourier transform infrared spectroscopic analyses confirmed that the chemical constituents of the extract were not altered by microwave radiation. The desired color strength (

K / S

) and dye-uptake (Q) were obtained at a dyeing time of 50 min, a pH of 7, a liquor ratio of 1:20, and a dyeing temperature of 60 °C. Varieties of elegant shades with desired colorfastness were developed through the involvement of less-toxic electrolyte and herbal mordants as functionalizing agents. BP extract is established as a potential sustainable and ecological colorant for textile industrial application. Full article

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

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13 pages, 14910 KiB

Open AccessArticle

Too Persistent to Resist: Aromaticity in 16e Osmapentalene Radicals Survives Regardless of Redox

by Shijie Pan, Jun Yan, Weitang Li, Zhigang Shuai and Jun Zhu

Chemistry 2025, 7(1), 22; https://doi.org/10.3390/chemistry7010022 - 8 Feb 2025

As one of the most important concepts in organic chemistry, aromaticity has attracted considerable attention from both theoretical and experimental chemists. Limited by the traditional rules (Hückel’s rules and Baird’s rules), species can only achieve aromaticity in a single state (S₀ or [...] Read more.

As one of the most important concepts in organic chemistry, aromaticity has attracted considerable attention from both theoretical and experimental chemists. Limited by the traditional rules (Hückel’s rules and Baird’s rules), species can only achieve aromaticity in a single state (S₀ or T₁) in most cases. In 2018, our group first reported 16 electron osmapentalene that showed aromaticity in both the S₀ and T₁ states, which is defined as adaptive aromaticity. In recent years, although adaptive aromatic compounds have been expanded, the adaptive aromatics containing metal-centered radical has not been reported. Here, we carry out density functional theory calculations to explore the aromaticity of the corresponding radicals based on osmapentalyne and osmapentalenes in their S₀ states. It is found that the corresponding radicals of adaptive aromatic osmapentalene exhibit aromaticity regardless of the radicals formed by oxidation or reduction, supported by a series of aromaticity indices including ΔBL, NICS, AICD, EDDB, and ELF. In contrast, for the nonaromatic or antiaromatic compound in the T₁ state, only its cationic radical shows aromaticity. Furthermore, the spin density localization on the metal center is the key factor for the radicals to achieve aromaticity. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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10 pages, 2021 KiB

Open AccessCommunication

Stable Fluorenyl Radicals Showing Tunable Doublet Emission

by Xudong Hou, Tingting Xu, Jun Zhu, Shaofei Wu and Jishan Wu

Chemistry 2025, 7(1), 21; https://doi.org/10.3390/chemistry7010021 - 7 Feb 2025

Neutral organic radicals with intrinsic spin-allowed doublet emission have emerged as a promising class of luminescent materials, garnering significant research interest. However, the development of stable luminescent radicals with tunable emission remains challenging. Herein, we present the synthesis of a series of 9-(2,4,6-trichlorophenyl)-substituted [...] Read more.

Neutral organic radicals with intrinsic spin-allowed doublet emission have emerged as a promising class of luminescent materials, garnering significant research interest. However, the development of stable luminescent radicals with tunable emission remains challenging. Herein, we present the synthesis of a series of 9-(2,4,6-trichlorophenyl)-substituted fluorenyl radicals functionalized with various substituents at the 3,6-positions. These radicals exhibit enhanced stability through efficient spin delocalization and kinetic protection. Notably, they display red-shifted photoluminescence compared to traditional polychlorotriphenylmethyl radicals, with maximum emission wavelengths ranging from 679 nm to 744 nm. The mechanisms underlying the doublet emission, as well as their electrochemical properties, have been thoroughly investigated. Full article

(This article belongs to the Special Issue Open-Shell Systems—a Memorial Issue Dedicated to Professor Masayoshi Nakano)

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