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Okura Y, Santis GD, Hirata K, Melissas VS, Ishiuchi SI, Fujii M, Xantheas SS. Switching of Protonation Sites in Hydrated Nicotine via a Grotthuss Mechanism. J Am Chem Soc 2024; 146:3023-3030. [PMID: 38261007 DOI: 10.1021/jacs.3c08922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The switching of the protonation sites in hydrated nicotine, probed by experimental infrared (IR) spectroscopy and theoretical ab initio calculations, is facilitated via a Grotthuss instead of a bimolecular proton transfer (vehicle) mechanism at the experimental temperature (T = 130 K) as unambiguously confirmed by experiments with deuterated water. In contrast, the bimolecular vehicle mechanism is preferred at higher temperatures (T = 300 K) as determined by theory. The Grotthuss mechanism for the concerted proton transfer results in the production of nicotine's bioactive and addictive pyrrolidine-protonated (Pyrro-H+) protomer with just 5 water molecules. Theoretical analysis suggests that the concerted proton transfer occurs via hydrogen-bonded bridges consisting of a 3 water molecule "core" that connects the pyridine protonated (Pyri-H+) with the pyrrolidine-protonated (Pyrro-H+) protomers. Additional water molecules attached as acceptors to the hydrogen-bonded "core" bridge result in lowering the reaction barrier of the concerted proton transfer down to less than 6 kcal/mol, which is consistent with the experimental observations.
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Affiliation(s)
- Yuika Okura
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Garrett D Santis
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Keisuke Hirata
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | | | - Shun-Ichi Ishiuchi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Sotiris S Xantheas
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States
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Papayannis DK, Papavasileiou KD, Melissas VS. A quantum mechanical approach to the oxidation mechanism of graphene oxide (GO). Heliyon 2024; 10:e24072. [PMID: 38298709 PMCID: PMC10827694 DOI: 10.1016/j.heliyon.2024.e24072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/20/2023] [Accepted: 01/03/2024] [Indexed: 02/02/2024] Open
Abstract
Elucidation of the reaction mechanism concerning the oxidation above the face and at the edge of a large, oxidized graphene (GO) cluster, namely C80H22O, by molecular oxygen in the first excited state (1Δg) was achieved with quantum mechanical calculations using the ONIOM two-layer method. Oxidation on the face of the aforementioned cluster leads to the formation of an ozone molecule, whereas oxygen molecule attack at the edge of the oxidized graphene surface either launches an ozonide -a five-membered ring species- formation during its outward approach or an 1,3-dioxetane -a four-membered ring species- production along its inward invasion. A detailed examination of the proposed pathways suggests that the ozonide formation should overcome almost one and a half times an adiabatic energy barrier with respect to the ozone production and is strongly exergonic by up to -50.1 kcal mol-1, supporting the experimental findings that both compounds are critically involved in the explosive deoxygenation of GO. On the other hand, the 1,3-dioxetane alternative pathway is considered even more exergonic, although it requires an overwhelming adiabatic energy barrier of 29.8 kcal mol-1 to accomplish its target.
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Affiliation(s)
- Dimitrios K. Papayannis
- Department of Material Science and Engineering, University of Ioannina, GR–451 10, Ioannina, Greece
| | - Konstantinos D. Papavasileiou
- Department of ChemoInformatics, NovaMechanics Ltd., CY-1070, Nicosia, Cyprus
- Division of Data Driven Innovation, Entelos Institute, CY-6059, Larnaca, Cyprus
- Department of ChemoInformatics, NovaMechanics MIKE., GR-185 45, Piraeus, Greece
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Diamataris IG, Peristeras LD, Papavasileiou KD, Melissas VS, Boulougouris GC. Statistical Inference of Rate Constants in Chemical and Biochemical Reaction Networks Using an "Inverse" Event-Driven Kinetic Monte Carlo Method. J Phys Chem B 2023; 127:9132-9143. [PMID: 37823789 DOI: 10.1021/acs.jpcb.3c03649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The use of rate models for networks of stochastic reactions is frequently used to comprehend the macroscopically observed dynamic properties of finite size reactive systems as well as their relationship to the underlying molecular events. Τhis particular approach usually stumbles on parameter derivation associated with stochastic kinetics, a quite demanding procedure. The present study incorporates a novel algorithm, which infers kinetic parameters from the system's time evolution, manifested as changes in molecular species populations. The proposed methodology reconstructs distributions required to infer kinetic parameters of a stochastic process pertaining to either a simulation or experimental data. The suggested approach accurately replicates rate constants of the stochastic reaction networks, which have evolved over time by event-driven Monte Carlo (MC) simulations using the Gillespie algorithm. Furthermore, our approach has been successfully used to estimate rate constants of association and dissociation events between molecular species developing during molecular dynamics (MD) simulations. We certainly believe that our method will be remarkably helpful for considering the macroscopic characteristic molecular roots related to stochastic physical and biological processes.
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Affiliation(s)
- Ioannis G Diamataris
- Laboratory of Computational Physical-Chemistry, Department of Molecular Biology and Genetics, University of Thrace, Alexandroupoulis GR-681 00, Greece
| | - Loukas D Peristeras
- Institute of Nanoscience and Nanotechnology, Molecular Thermodynamics and Modelling of Materials Laboratory, National Center for Scientific Research "Demokritos", Attikis, Agia Paraskevi GR-153 10, Greece
| | - Konstantinos D Papavasileiou
- Department of ChemoInformatics, NovaMechanics Ltd., Nicosia CY-1070, Cyprus
- Division of Data Driven Innovation, Entelos Institute, Larnaca CY-6059, Cyprus
- Department of ChemoInformatics, NovaMechanics MIKE., Piraeus GR-185 45, Greece
| | | | - Georgios C Boulougouris
- Laboratory of Computational Physical-Chemistry, Department of Molecular Biology and Genetics, University of Thrace, Alexandroupoulis GR-681 00, Greece
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Chattopadhyay A, Bedjanian Y, Romanias MN, Eleftheriou AD, Melissas VS, Papadimitriou VC, Burkholder JB. OH Radical and Chlorine Atom Kinetics of Substituted Aromatic Compounds: 4-chlorobenzotrifluoride ( p-ClC 6H 4CF 3). J Phys Chem A 2022; 126:5407-5419. [PMID: 35943137 DOI: 10.1021/acs.jpca.2c04455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanisms for the OH radical and Cl atom gas-phase reaction kinetics of substituted aromatic compounds remain a topic of atmospheric and combustion chemistry research. 4-Chlorobenzotrifluoride (p-chlorobenzotrifluoride, p-ClC6H4CF3, PCBTF) is a commonly used substituted aromatic volatile organic compound (VOC) in solvent-based coatings. As such, PCBTF is classified as a volatile chemical product (VCP) whose release into the atmosphere potentially impacts air quality. In this study, rate coefficients, k1, for the OH + PCBTF reaction were measured over the temperature ranges 275-340 and 385-940 K using low-pressure discharge flow-tube reactors coupled with a mass spectrometer detector in the ICARE/CNRS (Orléans, France) laboratory. k1(298-353 K) was also measured using a relative rate method in the thermally regulated atmospheric simulation chamber (THALAMOS; Douai, France). k1(T) displayed a non-Arrhenius temperature dependence with a negative temperature dependence between 275 and 385 K given by k1(275-385 K) = (1.50 ± 0.15) × 10-14 exp((705 ± 30)/T) cm3 molecule-1 s-1, where k1(298 K) = (1.63 ± 0.03) × 10-13 cm3 molecule-1 s-1 and a positive temperature dependence at elevated temperatures given by k1(470-950 K) = (5.42 ± 0.40) × 10-12 exp(-(2507 ± 45) /T) cm3 molecule-1 s-1. The present k1(298 K) results are in reasonable agreement with two previous 296 K (760 Torr, syn. air) relative rate measurements. The rate coefficient for the Cl-atom + PCBTF reaction, k2, was also measured in THALAMOS using a relative rate technique that yielded k2(298 K) = (7.8 ± 2) × 10-16 cm3 molecule-1 s-1. As part of this work, the UV and infrared absorption spectra of PCBTF were measured (NOAA; Boulder, CO, USA). On the basis of the UV absorption spectrum, the atmospheric instantaneous UV photolysis lifetime of PCBTF (ground level, midlatitude, Summer) was estimated to be 3-4 days, assuming a unit photolysis quantum yield. The non-Arrhenius behavior of the OH + PCBTF reaction over the temperature range 275 to 950 K is interpreted using a mechanism for the formation of an OH-PCBTF adduct and its thermochemical stability. The results from this study are included in a discussion of the OH radical and Cl atom kinetics of halogen substituted aromatic compounds for which only limited temperature-dependent kinetic data are available.
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Affiliation(s)
- Aparajeo Chattopadhyay
- Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3327, United States.,Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Yuri Bedjanian
- Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS 45071 Orléans Cedex 2, France
| | - Manolis N Romanias
- Center for Energy and Environment, Institut Mines-Télécom Nord Europe, Université Lille, F-59000 Lille, France
| | - Angeliki D Eleftheriou
- Laboratory of Photochemistry and Chemical Kinetics, Department of Chemistry, University of Crete, Vassilika Vouton, 70013, Heraklion, Crete, Greece
| | | | - Vassileios C Papadimitriou
- Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3327, United States.,Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States.,Laboratory of Photochemistry and Chemical Kinetics, Department of Chemistry, University of Crete, Vassilika Vouton, 70013, Heraklion, Crete, Greece
| | - James B Burkholder
- Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3327, United States
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Takis PG, Papavasileiou KD, Peristeras LD, Boulougouris GC, Melissas VS, Troganis AN. Unscrambling micro-solvation of –COOH and –NH groups in neat dimethyl sulfoxide: insights from 1H-NMR spectroscopy and computational studies. Phys Chem Chem Phys 2017; 19:13710-13722. [DOI: 10.1039/c7cp01592e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study investigates the interactions of –COOH and –NH groups in neat DMSO solutions, with special focus on their thermodynamics and kinetics.
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Affiliation(s)
- Panteleimon G. Takis
- Department of Biological Applications and Technology
- University of Ioannina
- GR-451 10 Ioannina
- Greece
| | - Konstantinos D. Papavasileiou
- National Center for Scientific Research “Demokritos”
- Institute of Nanoscience and Nanotechnology
- Molecular Thermodynamics and Modelling of Materials Laboratory (MTMML)
- GR-153 10 Aghia Paraskevi Attikis
- Greece
| | - Loukas D. Peristeras
- National Center for Scientific Research “Demokritos”
- Institute of Nanoscience and Nanotechnology
- Molecular Thermodynamics and Modelling of Materials Laboratory (MTMML)
- GR-153 10 Aghia Paraskevi Attikis
- Greece
| | - Georgios C. Boulougouris
- Department of Molecular Biology and Genetics
- Democritus University of Thrace
- GR-681 00 Alexandroupolis
- Greece
| | | | - Anastassios N. Troganis
- Department of Biological Applications and Technology
- University of Ioannina
- GR-451 10 Ioannina
- Greece
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Tsolis T, Papavasileiou KD, Divanis SA, Melissas VS, Garoufis A. How half sandwich ruthenium compounds interact with DNA while not being hydrolyzed; a comparative study. J Inorg Biochem 2016; 160:12-23. [PMID: 27118026 DOI: 10.1016/j.jinorgbio.2016.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 03/17/2016] [Accepted: 04/03/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Theodoros Tsolis
- Laboratory of Inorganic Chemistry, Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece
| | - Konstantinos D Papavasileiou
- Institute of Biology, Pharmaceutical Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., GR-116 35 Athens, Greece
| | - Spyridon A Divanis
- Section of Physical Chemistry, Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece
| | - Vasilios S Melissas
- Section of Physical Chemistry, Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece
| | - Achilleas Garoufis
- Laboratory of Inorganic Chemistry, Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece.
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Tzima TD, Ferentinos E, Maganas D, Melissas VS, Sanakis Y, Kyritsis P. Electronic and magnetic properties of the binuclear [Mn2{(OPPh2)2N}4] complex, as revealed by magnetometry, EPR and density functional broken-symmetry studies. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.07.084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Takis PG, Papavasileiou KD, Peristeras LD, Melissas VS, Troganis AN. Probing micro-solvation in “numbers”: the case of neutral dipeptides in water. Phys Chem Chem Phys 2013; 15:7354-62. [DOI: 10.1039/c3cp44606a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Takis PG, Melissas VS, Troganis AN. A “hidden” role of amino and imino groups is unveiled during the micro-solvation study of three biomolecule groups in water. NEW J CHEM 2012. [DOI: 10.1039/c2nj40390k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tzima TD, Sioros G, Duboc C, Kovala-Demertzi D, Melissas VS, Sanakis Y. Multifrequency electron paramagnetic resonance and theoretical studies of a Mn(II) (S=5/2) complex: The role of geometrical elements on the Zero Field Splitting parameters. Polyhedron 2009. [DOI: 10.1016/j.poly.2009.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Papavasileiou KD, Tzima TD, Sanakis Y, Melissas VS. A DFT Study of the Nitric Oxide and Tyrosyl Radical Interaction: A Proposed Radical Mechanism. Chemphyschem 2007; 8:2595-602. [DOI: 10.1002/cphc.200700434] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
The molecular geometries, conformational energies, and zero-point energies of di(trimethylsilylene)methylene have been determined from high-level quantum chemistry calculations. The results are further used in the parametrization of a classical potential energy function suitable for performing simulations of the corresponding polymer, namely, poly(dimethylsilylenemethylene). Di(trimethylsilylene)methylene geometrical parameter optimizations for a proper location of the global minimum and other local minima, constrained at certain dihedral and bond angles, were performed at both the B3LYP/6-311G and MP2(full)/6-311G levels of theory. The global minimum configuration is slightly displaced from a perfectly staggered geometry, approximately by 16.0 degrees, at both levels of theory. Molecular mechanics and Monte Carlo calculations for isolated polymer chains together with molecular dynamics runs for the modeled dimer provide very good results in terms of conformational and thermodynamic properties.
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Affiliation(s)
- Vasilios E Raptis
- Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece
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Mylonas M, Plakatouras JC, Hadjiliadis N, Papavasileiou KD, Melissas VS. An extremely stable Ni(II) complex derived from the hydrolytic cleavage of the C-terminal tail of histone H2A. J Inorg Biochem 2005; 99:637-43. [PMID: 15621298 DOI: 10.1016/j.jinorgbio.2004.11.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 11/09/2004] [Accepted: 11/18/2004] [Indexed: 10/26/2022]
Abstract
The C-terminal blocked tetrapeptides SHHK- and SAHK-, which represent the fragments produced from the hydrolysis of the hexapeptides' -TASHHK-, -TESHHK-, and -TESAHK- complexes with Ni(II), were synthesized and their interactions with Ni(II) ions were studied potentiometrically and spectroscopically. Both tetrapeptides interact strongly with Ni(II) ions leading to square-planar complexes with 4N {NH(2),2N(-),N(im)} coordination. The stability of the Ni-SHHK- complex is about 2 orders of magnitude higher than the Ni-SAHK- complex. Spectroscopic evidence and theoretical predictions suggest the positioning of the free imidazole ring, in the Ni-SHHK- complex, above the coordination plane, explaining the extra stability of the complex.
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Affiliation(s)
- Marios Mylonas
- Department of Chemistry, University of Ioannina, GR 451 10 Ioannina, Greece
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Papayannis DK, Melissas VS, Kosmas AM. Quantum mechanical studies of methyl bromoperoxide isomers and the CH3O + BrO reaction. Phys Chem Chem Phys 2003. [DOI: 10.1039/b302666n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Melissas VS, Truhlar DG. Interpolated variational transition-state theory and semiclassical tunneling calculations of the rate constant of the reaction hydroxyl + ethane at 200-3000 K. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100054a023] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Affiliation(s)
- Demetrios K. Papayannis
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, Greece GR- 451 10, and Molecular Modeling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, Agia Paraskevi Attikis, Greece GR- 153 10
| | - Agnie M. Kosmas
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, Greece GR- 451 10, and Molecular Modeling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, Agia Paraskevi Attikis, Greece GR- 153 10
| | - Vasilios S. Melissas
- Physical Chemistry Laboratory, Department of Chemistry, University of Ioannina, Greece GR- 451 10, and Molecular Modeling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, Agia Paraskevi Attikis, Greece GR- 153 10
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Bakalbassis EG, Chatzopoulou A, Melissas VS, Tsimidou M, Tsolaki M, Vafiadis A. Ab initio and density functional theory studies for the explanation of the antioxidant activity of certain phenolic acids. Lipids 2001; 36:181-90. [PMID: 11269699 DOI: 10.1007/s11745-001-0705-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ab initio and density functional theory molecular orbital calculations were carried out at both the HF/6-31 +G(d) and B3LYP/6-31+G(d) levels for the four antioxidants, p-hydroxycinnamic acid derivatives, namely, the p-coumaric, caffeic, ferulic, and sinapinic acid and the corresponding radicals, in an attempt to explain the structural dependency of the antioxidant activity of these compounds. Optimized resulting geometries, vibrational frequencies, absolute infrared intensities, and electron-donating ability are discussed. Both the high degree of conjugation and the extended spin delocalization in the phenoxyl radicals offer explanation for the scavenging activity of the four acids. In structurally related compounds, the calculated heat of formation value in radical formation appears as a meaningful molecular descriptor of antioxidant activity in accordance with experimental data. This becomes more clear at the B3LYP level.
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Affiliation(s)
- E G Bakalbassis
- Laboratory of Applied Quantum Chemistry, School of Chemistry, Aristotle University of Thessaloniki, Greece.
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Melissas VS, Drougas E, Bakalbassis EG, Kosmas AM. Dynamics of the OH + Cl2 → HOCl + Cl Reaction: Ab Initio Investigation and Quasiclassical Trajectory Calculations of Reaction Selectivity. J Phys Chem A 1999. [DOI: 10.1021/jp9928098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Vasilios S. Melissas
- Molecular Modelling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, 153 10 Agia Paraskevi Attikis, Greece, Laboratory of Physical Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece, and Laboratory of Applied Quantum Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, P.O. Box 135, 540 06 Thessaloniki, Greece
| | - Evangelos Drougas
- Molecular Modelling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, 153 10 Agia Paraskevi Attikis, Greece, Laboratory of Physical Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece, and Laboratory of Applied Quantum Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, P.O. Box 135, 540 06 Thessaloniki, Greece
| | - Evangelos G. Bakalbassis
- Molecular Modelling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, 153 10 Agia Paraskevi Attikis, Greece, Laboratory of Physical Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece, and Laboratory of Applied Quantum Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, P.O. Box 135, 540 06 Thessaloniki, Greece
| | - Agnie M. Kosmas
- Molecular Modelling of Materials Laboratory, Institute of Physical Chemistry, NRCPS “Demokritos”, 153 10 Agia Paraskevi Attikis, Greece, Laboratory of Physical Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece, and Laboratory of Applied Quantum Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, P.O. Box 135, 540 06 Thessaloniki, Greece
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Melissas VS, Truhlar DG. Interpolated variational transition state theory and tunneling calculations of the rate constant of the reaction OH+CH4 at 223–2400 K. J Chem Phys 1993. [DOI: 10.1063/1.465401] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Melissas VS, Truhlar DG, Garrett BC. Optimized calculations of reaction paths and reaction‐path functions for chemical reactions. J Chem Phys 1992. [DOI: 10.1063/1.462674] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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