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Search Results (185)

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Keywords = time-dependent density functional theory (TDDFT) calculations

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17 pages, 1725 KiB  
Article
Ring Opening upon Valence Shell Excitation in β-Butyrolactone: Experimental and Theoretical Methods
by Pedro A. S. Randi, Márcio H. F. Bettega, Nykola C. Jones, Søren V. Hoffmann, Małgorzata A. Śmiałek and Paulo Limão-Vieira
Molecules 2025, 30(15), 3137; https://doi.org/10.3390/molecules30153137 (registering DOI) - 26 Jul 2025
Viewed by 220
Abstract
The valence-shell electronic state spectroscopy of β-butyrolactone (CH3CHCH2CO2) is comprehensively investigated by employing experimental and theoretical methods. We report a novel vacuum ultraviolet (VUV) absorption spectrum in the photon wavelength range from 115 to 320 nm (3.9–10.8 [...] Read more.
The valence-shell electronic state spectroscopy of β-butyrolactone (CH3CHCH2CO2) is comprehensively investigated by employing experimental and theoretical methods. We report a novel vacuum ultraviolet (VUV) absorption spectrum in the photon wavelength range from 115 to 320 nm (3.9–10.8 eV), together with ab initio quantum chemical calculations at the time-dependent density functional (TD-DFT) level of theory. The dominant electronic excitations are assigned to mixed valence-Rydberg and Rydberg transitions. The fine structure in the CH3CHCH2CO2 photoabsorption spectrum has been assigned to C=O stretching, v7a, CH2 wagging, v14a, C–O stretching, v22a, and C=O bending, v26a modes. Photolysis lifetimes in the Earth’s atmosphere from 0 km up to 50 km altitude have been estimated, showing to be a non-relevant sink mechanism compared to reactions with the OH radical. The nuclear dynamics along the C=O and C–C–C coordinates have been investigated at the TD-DFT level of theory, where, upon electronic excitation, the potential energy curves show important carbonyl bond breaking and ring opening, respectively. Within such an intricate molecular landscape, the higher-lying excited electronic states may keep their original Rydberg character or may undergo Rydberg-to-valence conversion, with vibronic coupling as an important mechanism contributing to the spectrum. Full article
(This article belongs to the Special Issue Advances in Density Functional Theory (DFT) Calculation)
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19 pages, 4094 KiB  
Article
Precision Molecular Engineering of Alternating Donor–Acceptor Cycloparaphenylenes: Multidimensional Optoelectronic Response and Chirality Modulation via Polarization-Driven Charge Transfer
by Danmei Zhu, Xinwen Gai, Yi Zou, Ying Jin and Jingang Wang
Molecules 2025, 30(15), 3127; https://doi.org/10.3390/molecules30153127 - 25 Jul 2025
Viewed by 143
Abstract
In this study, three alternating donor–acceptor (D–A) type [12]cycloparaphenylene ([12]CPP) derivatives ([12]CPP 1a, 2a, and 3a) were designed through precise molecular engineering, and their multidimensional photophysical responses and chiroptical properties were systematically investigated. The effects of the alternating D–A architecture on electronic structure, [...] Read more.
In this study, three alternating donor–acceptor (D–A) type [12]cycloparaphenylene ([12]CPP) derivatives ([12]CPP 1a, 2a, and 3a) were designed through precise molecular engineering, and their multidimensional photophysical responses and chiroptical properties were systematically investigated. The effects of the alternating D–A architecture on electronic structure, excited-state dynamics, and optical behavior were elucidated through density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The results show that the alternating D–A design significantly reduced the HOMO–LUMO energy gap (e.g., 3.11 eV for [12]CPP 2a), enhanced charge transfer characteristics, and induced pronounced red-shifted absorption. The introduction of an imide-based acceptor ([12]CPP 2a) further strengthened the electron push-pull interaction, exhibiting superior performance in two-photon absorption, while the symmetrically multifunctionalized structure ([12]CPP 3a) predominantly exhibited localized excitation with the highest absorption intensity but lacked charge transfer features. Chiral analysis reveals that the alternating D–A architecture modulated the distribution of chiral signals, with [12]CPP 1a displaying a strong Cotton effect in the low-wavelength region. These findings not only provide a theoretical basis for the molecular design of functionalized CPP derivatives, but also lay a solid theoretical foundation for expanding their application potential in optoelectronic devices and chiral functional materials. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
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15 pages, 1943 KiB  
Article
Theoretical Study on the Influence of Building Blocks in Benzotrithiophene-Based Covalent Organic Frameworks for Optoelectronic Properties
by Xu Li, Yue Niu, Kexin Ma, Xin Huang, Qingji Wang and Zhiqiang Liang
Catalysts 2025, 15(7), 647; https://doi.org/10.3390/catal15070647 - 2 Jul 2025
Viewed by 410
Abstract
Covalent organic frameworks (COFs) have emerged as unique catalysts for photocatalysis; however, the relationship between their building block units and optoelectronic properties remains elusive. Herein, we explored the influence of building blocks on the optoelectronic properties of benzotrithiophene-based COFs (BTT-COFs) using density functional [...] Read more.
Covalent organic frameworks (COFs) have emerged as unique catalysts for photocatalysis; however, the relationship between their building block units and optoelectronic properties remains elusive. Herein, we explored the influence of building blocks on the optoelectronic properties of benzotrithiophene-based COFs (BTT-COFs) using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The calculation results suggested that three critical factors—the conjugated structure, planarity, and the introduction of nitrogen heteroatoms—significantly influenced charge separation and transfer within BTT-COFs. Structure–property relationships were established through several critical quantitative parameters, such as Sr, t, and CT. Among seven BTT-COFs, BTT-Tpa (Tpa: 4,4′,4″-triaminotriphenylamine) exhibited the most efficient charge separation and the highest charge transfer capability due to the electronegativity of triphenylamine, the delocalization of its lone pair electrons, and its unique star-shaped configuration. These theoretical results will provide an essential foundation for selecting donor–acceptor units in the design of novel COF materials for photocatalytic reaction applications. Full article
(This article belongs to the Section Computational Catalysis)
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26 pages, 3934 KiB  
Article
Structural and Spectroscopic Properties of Magnolol and Honokiol–Experimental and Theoretical Studies
by Jacek Kujawski, Beata Drabińska, Katarzyna Dettlaff, Marcin Skotnicki, Agata Olszewska, Tomasz Ratajczak, Marianna Napierała, Marcin K. Chmielewski, Milena Kasprzak, Radosław Kujawski, Aleksandra Gostyńska-Stawna and Maciej Stawny
Int. J. Mol. Sci. 2025, 26(13), 6085; https://doi.org/10.3390/ijms26136085 - 25 Jun 2025
Viewed by 324
Abstract
This study presents an integrated experimental and theoretical investigation of two pharmacologically significant neolignans—magnolol and honokiol—with the aim of characterizing their structural and spectroscopic properties in detail. Experimental Fourier-transform infrared (FT-IR), ultraviolet–visible (UV-Vis), and nuclear magnetic resonance (1H NMR) spectra were [...] Read more.
This study presents an integrated experimental and theoretical investigation of two pharmacologically significant neolignans—magnolol and honokiol—with the aim of characterizing their structural and spectroscopic properties in detail. Experimental Fourier-transform infrared (FT-IR), ultraviolet–visible (UV-Vis), and nuclear magnetic resonance (1H NMR) spectra were recorded and analyzed. To support and interpret these findings, a series of density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were conducted using several hybrid and long-range corrected functionals (B3LYP, CAM-B3LYP, M06X, PW6B95D3, and ωB97XD). Implicit solvation effects were modeled using the CPCM approach across a variety of solvents. The theoretical spectra were systematically compared to experimental data to determine the most reliable computational approaches. Additionally, natural bond orbital (NBO) analysis, molecular electrostatic potential (MEP) mapping, and frontier molecular orbital (FMO) visualization were performed to explore electronic properties and reactivity descriptors. The results provide valuable insight into the structure–spectrum relationships of magnolol and honokiol and establish a computational benchmark for further studies on neolignan analogues. Full article
(This article belongs to the Section Molecular Biophysics)
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12 pages, 1111 KiB  
Article
Structure–Function Relationship of Novel Tetrakis (Mercapto-Terphenyl)Benzene Cobalt (II) Phthalocyanines: Synthesis and Computational Evaluation
by Sevil Sener and Nursel Acar-Selcuki
Molecules 2025, 30(13), 2693; https://doi.org/10.3390/molecules30132693 - 22 Jun 2025
Viewed by 437
Abstract
This study introduces a newly synthesized Co(II) phthalocyanine complex (Co-Pc, 4) incorporating two (mercapto-terphenyl)thio-dione substituents, along with a detailed exploration of its structural, spectroscopic, and binding characteristics. The key precursor, 4-[(4′′-mercapto-[1,1′:4′,1′′-terphenyl]-4-yl)thio]phthalonitrile (compound 3), was first obtained and subsequently used to construct [...] Read more.
This study introduces a newly synthesized Co(II) phthalocyanine complex (Co-Pc, 4) incorporating two (mercapto-terphenyl)thio-dione substituents, along with a detailed exploration of its structural, spectroscopic, and binding characteristics. The key precursor, 4-[(4′′-mercapto-[1,1′:4′,1′′-terphenyl]-4-yl)thio]phthalonitrile (compound 3), was first obtained and subsequently used to construct the phthalocyanine macrocycle through cyclotetramerization in the presence of cobalt and zinc salts under heat and vacuum in dimethylformamide. The resulting compounds (3 and 4) were characterized using a comprehensive array of analytical techniques, including elemental analysis, UV–Vis spectroscopy, FT-IR, 1H-NMR, and Q-TOF mass spectrometry. Additionally, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to elucidate the electronic structure and geometrical features of Co-Pc 4, providing theoretical support for the experimental findings. The integration of theoretical and experimental findings provides in-depth insight into the electronic behavior and reactivity of compound 4, highlighting its promise as a candidate for photovoltaic applications. Further studies may investigate how structural modifications influence these properties, potentially leading to improved device performance. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
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17 pages, 2784 KiB  
Article
Boron-Centered Compounds: Exploring the Optical Properties of Spiro Derivatives with Imidazo[1,5-a]Pyridines
by Anita Cinco, G. Attilio Ardizzoia, Stefano Brenna, Bruno Therrien and Gioele Colombo
Molecules 2025, 30(12), 2552; https://doi.org/10.3390/molecules30122552 - 11 Jun 2025
Viewed by 645
Abstract
Five boron-centered spiro compounds with imidazo[1,5-a]pyridin-3-yl phenols as ligands were synthesized and thoroughly characterized through 1H-NMR, 13C-NMR, infrared spectroscopy, and X-ray single crystal analysis. The fluorescence properties of these compounds in solution and in the solid state were investigated, [...] Read more.
Five boron-centered spiro compounds with imidazo[1,5-a]pyridin-3-yl phenols as ligands were synthesized and thoroughly characterized through 1H-NMR, 13C-NMR, infrared spectroscopy, and X-ray single crystal analysis. The fluorescence properties of these compounds in solution and in the solid state were investigated, revealing blue emission with wavelengths maxima dependent on the electronic properties of the substituents on the ligands in solution, and an orange-red emission in the solid state. Time-Dependent Density Functional Theory (TD-DFT) calculations were performed to describe the nature of the transitions Full article
(This article belongs to the Special Issue Boron Chemistry and Applications)
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14 pages, 1586 KiB  
Article
Stability-Guided Formulation of a Light-Sensitive D-LSD Capsule for Clinical Investigation
by Bernard Do, Luc Mallet, Maxime Annereau, Danielle Libong, Audrey Solgadi, Florence Vorspan, Muriel Paul and Philippe-Henri Secretan
Pharmaceutics 2025, 17(6), 767; https://doi.org/10.3390/pharmaceutics17060767 - 11 Jun 2025
Viewed by 593
Abstract
Background/Objectives: D-lysergic acid diethylamide (D-LSD) is under investigation as a potential therapeutic strategy for alcohol use disorder (AUD). However, the extreme light sensitivity of D-LSD presents a significant challenge in developing suitable pharmaceutical forms, particularly for clinical trial settings. This study proposes a [...] Read more.
Background/Objectives: D-lysergic acid diethylamide (D-LSD) is under investigation as a potential therapeutic strategy for alcohol use disorder (AUD). However, the extreme light sensitivity of D-LSD presents a significant challenge in developing suitable pharmaceutical forms, particularly for clinical trial settings. This study proposes a liquid-filled capsule formulation designed to provide accurate dosing while protecting D-LSD from photodegradation. Methods: To support formulation development and ensure its suitability as an investigational medicinal product, a multi-tiered analytical strategy was employed. This included liquid chromatography coupled with ion mobility spectrometry and mass spectrometry (LC-IM-MS), along with quantum chemical calculations (density functional theory (DFT) and time dependent-DFT (TD-DFT)), to ensure robust and orthogonal structural characterization of degradation products. Results: Photostress studies demonstrated that while D-LSD in solution rapidly degrades into photoisomers and photooxidative byproducts, the capsule formulation markedly mitigates these transformations under ICH-compliant conditions. Conclusions: These findings highlight the essential role of orthogonal stability profiling in guiding formulation development and demonstrate that this approach may offer a viable, photostable platform for future clinical investigation of D-LSD in the treatment of AUD. Full article
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27 pages, 19227 KiB  
Article
Copper(II) Complex with a 3,3′-Dicarboxy-2,2′-Dihydroxydiphenylmethane-Based Carboxylic Ligand: Synthesis, Spectroscopic, Optical, Density Functional Theory, Cytotoxic, and Molecular Docking Approaches for a Potential Anti-Colon Cancer Control
by Ayman H. Ahmed, Ibrahim O. Althobaiti, Kamal A. Soliman, Yazeed M. Asiri, Ebtsam K. Alenezy, Saad Alrashdi and Ehab S. Gad
Inorganics 2025, 13(5), 151; https://doi.org/10.3390/inorganics13050151 - 6 May 2025
Viewed by 869
Abstract
The chemical interaction of salicylic acid, formaldehyde, and sulfuric acid produced a disalicylic ligand (3,3′-dicarboxy-2,2′-dihydroxydiphenylmethane, DCM), which was then allowed to coordinate with copper (II) ions. The solid compounds’ chemical structures were determined using elemental analysis, UV-Vis, FT-IR, MS, 1H-NMR, PXRD, SEM, [...] Read more.
The chemical interaction of salicylic acid, formaldehyde, and sulfuric acid produced a disalicylic ligand (3,3′-dicarboxy-2,2′-dihydroxydiphenylmethane, DCM), which was then allowed to coordinate with copper (II) ions. The solid compounds’ chemical structures were determined using elemental analysis, UV-Vis, FT-IR, MS, 1H-NMR, PXRD, SEM, TEM, magnetic studies, as well as molecular modeling based on DFT (density functional theory) calculations. It was proposed that the ligand coordinates in a tetradentate fashion with the copper ion to give a square-planar binuclear complex. A significant difference in the diffraction patterns between Cu(II)–DCM (amorphous) and DCM (crystalline) was displayed using an X-ray diffraction analysis. Spherical granules were identified throughout through morphology analysis using SEM and TEM. UV-Vis spectra were used to quantify the optical characteristics such as the energy gap, optical conductivity, refractive index, and penetration depth. The band gap values that lie within the semiconductor region suggested that the compounds could be used for electronic applications. The optimized structure of the synthesized Cu(II)–DCM complex was investigated using DFT and TD-DFT (time-dependent density functional theory) at the B3LYP/6-31G(d, p) level, with the LANL2DZ basis set for Cu in an ethanol solvent and the gas environment modeled by CPCM. The experimental data suggest a square-planar geometry of the Cu(II) binuclear complex. The theoretical calculations support the proposed structure of the compound. The cytotoxicity of the DCM against HCT–116 (human colon cancer) cells was tested, and the outcome exhibited good inhibitions of growth. A molecular docking (MD) examination was carried out to illustrate the binding mode/affinity of the prepared compounds (DCM and Cu(II)–DCM) in the active site of the receptor protein [CDK2 enzyme, PDB ID: 6GUE]. The compounds formed hydrogen bonds with the amino acid residues of the protein, increasing the binding affinity from −7.2 to −9.3 kcal/mol through the coordination process. The information from this current study, particularly the copper complex, is beneficial for exploring new compounds that have anticancer potential. Full article
(This article belongs to the Special Issue Applications and Future Trends for Novel Copper Complexes)
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15 pages, 5164 KiB  
Article
Preparation, Thermal, and Optical Properties of D-A-Type Molecules Based on 1,3,5-Triazine for Violet-Blue Fluorescent Materials
by Lu Wang, Enwang Du, Zhi Liu and Zhiqiang Liu
Materials 2025, 18(9), 2043; https://doi.org/10.3390/ma18092043 - 29 Apr 2025
Viewed by 430
Abstract
Organic violet-blue fluorescent materials have garnered significant interest for a broad spectrum of applications. A series of triazine-based molecules, that is, 2,4,6-tri(9H-carbazol-9-yl)-1,3,5-triazine (TCZT), 2,4,6-tri(1H-indol-1-yl)-1,3,5-triazine (TIDT), and 2,4,6-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)-1,3,5-triazine (TDBCZT), exhibiting violet-blue emission were synthesized via a catalyst-free aromatic nucleophilic substitution reaction. These compounds possess [...] Read more.
Organic violet-blue fluorescent materials have garnered significant interest for a broad spectrum of applications. A series of triazine-based molecules, that is, 2,4,6-tri(9H-carbazol-9-yl)-1,3,5-triazine (TCZT), 2,4,6-tri(1H-indol-1-yl)-1,3,5-triazine (TIDT), and 2,4,6-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)-1,3,5-triazine (TDBCZT), exhibiting violet-blue emission were synthesized via a catalyst-free aromatic nucleophilic substitution reaction. These compounds possess a non-planar and twisted structure with favorable charge-transfer characteristics, demonstrating excellent thermal stability (decomposition temperatures of 370 °C, 384 °C, and 230 °C, respectively). Cyclic voltammetry analysis, combined with time-dependent density functional theory (TD-DFT) calculations at the B3LYP/6-31G(d) level, offered detailed insights into their electronic structures and electrochemical properties. Optical properties were systematically characterized using Ultraviolet–visible (UV–Vis) absorption and photoluminescence (PL) spectroscopy. The compounds exhibited violet-blue luminescence with emission peaks located at 397 nm, 383 nm, and 402 nm in toluene, respectively. In their respective films, the compounds exhibited varying degrees of spectral shifts, with emission peaks at 408 nm, 381 nm, and 369 nm. Moreover, the CIE (Commission Internationale de l’Éclairage) coordinates of TIDT in toluene were (0.155, 0.067), indicative of excellent violet purity. These compounds demonstrated significant two-photon absorption (TPA) properties, with cross-sections of 4.6 GM, 15.3 GM, and 7.4 GM, respectively. Notably, they exhibited large molar absorptivities and substantial photoluminescence quantum yields (PLQYs), suggesting their potential for practical applications as violet-blue fluorescent materials. Full article
(This article belongs to the Section Optical and Photonic Materials)
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20 pages, 2160 KiB  
Article
Conformational Locking of the Geometry in Photoluminescent Cyclometalated N^C^N Ni(II) Complexes
by Maryam Niazi, Iván Maisuls, Lukas A. Mai, Sascha A. Schäfer, Alex Oster, Lukas Santiago Diaz, Dirk M. Guldi, Nikos L. Doltsinis, Cristian A. Strassert and Axel Klein
Molecules 2025, 30(9), 1901; https://doi.org/10.3390/molecules30091901 - 24 Apr 2025
Viewed by 603
Abstract
In our research aimed at replacing precious transition metals like platinum with abundant base metals such as nickel for efficient triplet emitters, we synthesized and studied Ni(II) complexes [Ni(LNHR)Cl]. These complexes containing the N^C^N cyclometalating dipyridyl-phenide ligand, equipped with pending H-bonding [...] Read more.
In our research aimed at replacing precious transition metals like platinum with abundant base metals such as nickel for efficient triplet emitters, we synthesized and studied Ni(II) complexes [Ni(LNHR)Cl]. These complexes containing the N^C^N cyclometalating dipyridyl-phenide ligand, equipped with pending H-bonding amine groups (NH(C₆H₅) (LNHPh) and NH(C₆H₅CH₂), ClLNHBn). Molecular structures determined from experimental X-ray diffractometry and density functional theory (DFT) calculations in the ground state showed marked deviation of the Cl coligand (ancillary ligand) from the ideal planar coordination, with τ4 values of 0.35 and 0.33, respectively, along with hydrogen bonding interactions of the ligand NH function with the Cl coligand. The complexes exhibit long-wavelength absorption bands at approximately 425 nm in solution, with the experimental spectra being accurately reproduced through time-dependent density functional theory (TD-DFT) calculations. Vibrationally structured emission profiles and steady-state photoluminescence quantum yields of 30% for [Ni(LNHPh)Cl] and 40% for [Ni(LNHBn)Cl] (along with dual excited state lifetimes in the ns and in the ms range) were found in frozen 2-methyl-tetrahydrofuran (2MeTHF) glassy matrices at 77 K. Furthermore, within a poly(methyl methacrylate) matrix, the complexes showed emission bands centered at around 550 nm within a temperature range from 6 K to 300 K with lifetimes similar to 77 K. Based on TD-DFT potential scans along the metal–ligand (Ni–N) coordinate, we found that in a rigid environment that restricts the geometry to the Franck-Condon region, either the triplet T5 or the singlet S4 state could contribute to the photoluminescence. Full article
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17 pages, 3207 KiB  
Article
Cyclohexane Vibronic States: A Combined VUV Spectroscopy and Theoretical Study
by Edvaldo Bandeira, Alessandra S. Barbosa, Nykola C. Jones, Søren V. Hoffmann, Márcio H. F. Bettega and Paulo Limão-Vieira
Molecules 2025, 30(7), 1493; https://doi.org/10.3390/molecules30071493 - 27 Mar 2025
Viewed by 363
Abstract
In this work, we provide results from a joint experimental and theoretical study of the vibronic features of cyclohexane (C6H12) in the photon energy range of 6.8–10.8 eV (182–115 nm). The high-resolution vacuum ultraviolet (VUV) photoabsorption measurements, together with [...] Read more.
In this work, we provide results from a joint experimental and theoretical study of the vibronic features of cyclohexane (C6H12) in the photon energy range of 6.8–10.8 eV (182–115 nm). The high-resolution vacuum ultraviolet (VUV) photoabsorption measurements, together with quantum chemical calculations at the time-dependent density functional theory (TDDFT) level, have helped to assign the major electronic excitations to mixed valence–Rydberg and Rydberg transitions. The C6H12 photoabsorption spectrum shows fine structure which has been assigned to CH2 scissoring, v3a1g, CH2 rocking, v4a1g, C–C stretching, v5a1g, and CCC bending/CC torsion, v24eg, modes. Molecular structure calculations at the DFT level for the neutral and cationic electronic ground-states have shown the relevant structural changes that are operative in the higher-lying electronic states. Photolysis lifetimes in the Earth’s atmosphere are shown to be irrelevant, while the main atmospheric sink mechanism is the reaction with the OH radical. Potential energy curves have been obtained at the TDDFT level of theory, showing the relevance of interchange character mainly involving the CH2 scissoring, v3a1g, and CH2 rocking, v4a1g, modes, while Jahn–Teller distortion yields weak vibronic coupling involving the non-totally symmetric CCC bending/CC torsion, v24eg, mode. Full article
(This article belongs to the Special Issue Exclusive Feature Papers in Physical Chemistry, 3nd Edition)
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12 pages, 1562 KiB  
Article
Bioactive Steroids with Structural Diversity from the South China Sea Soft Coral Lobophytum sp. and Sponge Xestospongia sp.
by Lin-Mao Ke, Zi-Ru Zhang, Song-Wei Li, Yan-Bo Zeng, Ming-Zhi Su and Yue-Wei Guo
Mar. Drugs 2025, 23(1), 36; https://doi.org/10.3390/md23010036 - 13 Jan 2025
Cited by 1 | Viewed by 1097
Abstract
A chemical investigation of the soft coral Lobophytum sp. and the sponge Xestospongia sp. from the South China Sea led to the isolation of five steroids, including two new compounds (1 and 4) and one known natural product (3). [...] Read more.
A chemical investigation of the soft coral Lobophytum sp. and the sponge Xestospongia sp. from the South China Sea led to the isolation of five steroids, including two new compounds (1 and 4) and one known natural product (3). Compounds 13 were derived from the soft coral Lobophytum sp., while 4 and 5 were obtained from the sponge Xestospongia sp. The structures of these compounds were determined by extensive spectroscopic analysis, the time-dependent density functional theory–electronic circular dichroism (TDDFT-ECD) calculation method, and comparison with the spectral data previously reported in the literature. The antibacterial and anti-inflammatory activities of isolated compounds were evaluated in vitro. Compounds 13, 4, and 5 exhibited weak antibacterial activity against vancomycin-resistant Enterococcus faecium G1, Streptococcus parauberis KSP28, Photobacterium damselae FP2244, Lactococcus garvieae FP5245, and Pseudomonas aeruginosa ZJ028. Moreover, compound 3 showed significant anti-inflammatory activity by inhibiting lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells, with an IC50 value of 13.48 μM. Full article
(This article belongs to the Special Issue Bioactive Compounds from Soft Corals and Their Derived Microorganisms)
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16 pages, 8337 KiB  
Article
Computational Chemistry Study of pH-Responsive Fluorescent Probes and Development of Supporting Software
by Ximeng Zhu, Yongchun Wei and Xiaogang Liu
Molecules 2025, 30(2), 273; https://doi.org/10.3390/molecules30020273 - 12 Jan 2025
Viewed by 1572
Abstract
This study employs quantum chemical computational methods to predict the spectroscopic properties of fluorescent probes 2,6-bis(2-benzimidazolyl)pyridine (BBP) and (E)-3-(2-(1H-benzo[d]imidazol-2-yl)vinyl)-9-(2-(2-methoxyethoxy)ethyl)-9H-carbazole (BIMC). Using time-dependent density functional theory (TDDFT), we successfully predicted the fluorescence emission wavelengths of BBP [...] Read more.
This study employs quantum chemical computational methods to predict the spectroscopic properties of fluorescent probes 2,6-bis(2-benzimidazolyl)pyridine (BBP) and (E)-3-(2-(1H-benzo[d]imidazol-2-yl)vinyl)-9-(2-(2-methoxyethoxy)ethyl)-9H-carbazole (BIMC). Using time-dependent density functional theory (TDDFT), we successfully predicted the fluorescence emission wavelengths of BBP under various protonation states, achieving an average deviation of 6.0% from experimental excitation energies. Molecular dynamics simulations elucidated the microscopic mechanism underlying BBP’s fluorescence quenching under acidic conditions. The spectroscopic predictions for BIMC were performed using the STEOM-DLPNO-CCSD method, yielding an average deviation of merely 0.57% from experimental values. Based on Einstein’s spontaneous emission formula and empirical internal conversion rate formulas, we calculated fluorescence quantum yields for spectral intensity calibration, enabling the accurate prediction of experimental spectra. To streamline the computational workflow, we developed and open-sourced the EasySpecCalc software v0.0.1 on GitHub, aiming to facilitate the design and development of fluorescent probes. Full article
(This article belongs to the Special Issue Fluorescent Probes in Biomedical Detection and Imaging)
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15 pages, 7521 KiB  
Article
A Novel Fluorescent Chemosensor Based on Rhodamine Schiff Base: Synthesis, Photophysical, Computational and Bioimaging Application in Live Cells
by Oyedoyin Aduroja, Roosevelt Shaw, Sisay Uota, Isaac Abiye, James Wachira and Fasil Abebe
Inorganics 2025, 13(1), 5; https://doi.org/10.3390/inorganics13010005 - 27 Dec 2024
Cited by 3 | Viewed by 1114
Abstract
A novel rhodamine-6G derivative RdN was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb2+ and Cu2+ ions in a solution of CH [...] Read more.
A novel rhodamine-6G derivative RdN was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb2+ and Cu2+ ions in a solution of CH3CN/H2O (9:1, v/v). The spirolactam ring of RdN opens upon complexation with the cations, forming a highly fluorescent complex and a visible color change in the solution. The compound RdN was further studied with the help of computational methods such as the Density Functional Theory (DFT) method and time-dependent density theory (TD-DFT) calculations to study the binding interactions and properties of the molecule. DFT calculations and job plot data supported the 2:1 complex formation between RdN and Pb2+/Cu2+. The limit of detection for Pb2+ was determined to be 0.112 µM and 0.130 µM for Cu2+. The probe RdN was applied to the image of Pb2+ and Cu2+ ions in living cells and is safe for biomedical applications. It is used to monitor Pb2+ in environmental water samples. Full article
(This article belongs to the Special Issue Synthesis and Application of Luminescent Materials, 2nd Edition)
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20 pages, 8137 KiB  
Article
A Simple and Rapid “Turn-On” Fluorescent Probe Based on Binuclear Schiff Base for Zn2+ and Its Application in Cell Imaging and Test Strips
by Jinghui Cheng, Yi Li, Zhiye Zhu, Huijuan Guan, Jinsong Zhai, Yibing Xiang and Man Wang
Molecules 2024, 29(24), 5850; https://doi.org/10.3390/molecules29245850 - 11 Dec 2024
Viewed by 1057
Abstract
A series of colorful binuclear Schiff bases derived from the different diamine bridges including 1,2- ethylenediamine (bis-Et-SA, bis-Et-4-NEt2, bis-Et-5-NO2, bis-Et-Naph), 1,2-phenylenediamine (bis-Ph-SA, bis-Ph-4-NEt2, bis-Ph-5-NO2, bis-Ph-Naph), dicyano-1,2-ethenediamine (bis-CN-SA, bis-CN-4-NEt2, bis-CN-5-NO2, bis-CN-Naph) have [...] Read more.
A series of colorful binuclear Schiff bases derived from the different diamine bridges including 1,2- ethylenediamine (bis-Et-SA, bis-Et-4-NEt2, bis-Et-5-NO2, bis-Et-Naph), 1,2-phenylenediamine (bis-Ph-SA, bis-Ph-4-NEt2, bis-Ph-5-NO2, bis-Ph-Naph), dicyano-1,2-ethenediamine (bis-CN-SA, bis-CN-4-NEt2, bis-CN-5-NO2, bis-CN-Naph) have been designed and prepared. The optical properties of these binuclear Schiff base ligands were fully determined by UV–Vis absorption spectroscopy, fluorescence emission spectroscopy, and time-dependent-density functional theory (TD-DFT) calculations. The inclusion of D-A systems and/or π-extended systems in these binuclear Schiff base ligands not only enables adjustable RGB light absorption and emission spectra (300~700 nm) but also yields high fluorescence quantum efficiencies of up to 0.84 in MeCN solution. Then, with the ESIPT (excited-state intramolecular proton transfer) property, fluorescence analysis showed that the probe bis-Et-SA and bis-Ph-SA could recognize Zn2+ via the “turn on” mode in the MeCN solution. During the detection process, bis-Et-SA and bis-Ph-SA demonstrate rapid response and high selectivity upon the addition of Zn2+. The coordination of Zn2+ with the oxygen atom and Schiff base nitrogen atom in a tetrahedral geometry is confirmed by Job’s plot, FT-IR, and 1H NMR spectroscopy. In addition, the paper test and Hela cells were successfully carried out to detect Zn2+. Moreover, the sensitivity of bis-Et-SA and bis-Ph-SA is much better than that of those Schiff base ligands containing only one chelating unit [O^N^N^O]. Full article
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