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Malloum A, Conradie J. Microsolvation of phenol in water: structures, hydration free energy and enthalpy. MOLECULAR SIMULATION 2023. [DOI: 10.1080/08927022.2022.2163674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Alhadji Malloum
- Department of Chemistry, University of the Free State, Bloemfontein, South Africa
- Department of Physics, Faculty of Science, University of Maroua, Maroua, Cameroon
| | - Jeanet Conradie
- Department of Chemistry, University of the Free State, Bloemfontein, South Africa
- Department of Chemistry, UiT – The Arctic University of Norway, Tromsø, Norway
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Franco LR, Toledo KCF, Matias TA, Benavides PA, Cezar HM, Araujo CM, Coutinho K, Araki K. Unraveling the acid-base characterization and solvent effects on the structural and electronic properties of a bis-bidentate bridging ligand. Phys Chem Chem Phys 2022; 24:10222-10240. [PMID: 35420602 DOI: 10.1039/d1cp03912a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the interactions and the solvent effects on the distribution of several species in equilibrium and how it can influence the 1H-NMR properties, spectroscopy (UV-vis absorption), and the acid-base equilibria can be especially challenging. This is the case of a bis-bidentate bridging ligand bis(2-pyridyl)-benzo-bis(imidazole), where the two pyridyl and four imidazolyl nitrogen atoms can be protonated in different ways, depending on the solvent, generating many isomeric/tautomeric species. Herein, we report a combined theoretical-experimental approach based on a sequential quantum mechanics/molecular mechanics procedure that was successfully applied to describe in detail the acid-base characterization and its effects on the electronic properties of such a molecule in solution. The calculated free-energies allowed the identification of the main species present in solution as a function of the solvent polarity, and its effects on the magnetic shielding of protons (1H-NMR chemical shifts), the UV-vis absorption spectra, and the acid-base equilibrium constants (pKas) in aqueous solution. Three acid-base equilibrium constants were experimentally/theoretically determined (pKa1 = 1.3/1.2, pKa2 = 2.1/2.2 and pKa5 = 10.1/11.3) involving mono-deprotonated and mono-protonated cis and trans species. Interestingly, other processes with pKa3 = 3.7 and pKa4 = 6.0 were also experimentally determined and assigned to the protonation and deprotonation of dimeric species. The dimerization of the most stable neutral species was investigated by Monte Carlo simulations and its electronic effects were considered for the elucidation of the UV-vis absorption bands, revealing transitions mainly with the charge-transfer characteristic and involving both the monomeric species and the dimeric species. The good matching of the theoretical and experimental results provides an atomistic insight into the solvent effects on the electronic properties of this bis-bidentate bridging ligand.
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Affiliation(s)
- Leandro Rezende Franco
- Instituto de Física, Universidade de São Paulo, Cidade Universitária, 05508-090 São Paulo, SP, Brazil. .,Department of Engineering and Physics, Karlstad University, 65188 Karlstad, Sweden
| | | | - Tiago Araujo Matias
- Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, Butantã, 05508-000 São Paulo, SP, Brazil.
| | - Paola Andrea Benavides
- Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, Butantã, 05508-000 São Paulo, SP, Brazil.
| | - Henrique Musseli Cezar
- Instituto de Física, Universidade de São Paulo, Cidade Universitária, 05508-090 São Paulo, SP, Brazil.
| | - C Moyses Araujo
- Department of Engineering and Physics, Karlstad University, 65188 Karlstad, Sweden.,Materials Theory Division, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, 75120 Uppsala, Sweden
| | - Kaline Coutinho
- Instituto de Física, Universidade de São Paulo, Cidade Universitária, 05508-090 São Paulo, SP, Brazil.
| | - Koiti Araki
- Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, Butantã, 05508-000 São Paulo, SP, Brazil.
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Chou S, Lin S, Chen H, Wu Y. Infrared absorption spectra of phenoxide anions isolated in solid argon. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sheng‐Lung Chou
- Scientific Research Division National Synchrotron Radiation Research Center Hsinchu Taiwan
| | - Shu‐Yu Lin
- Scientific Research Division National Synchrotron Radiation Research Center Hsinchu Taiwan
- Department of Applied Chemistry National Yang Ming Chiao Tung University Hsinchu Taiwan
| | - Hui‐Fen Chen
- Department of Medicinal and Applied Chemistry Kaohsiung Medical University Kaohsiung Taiwan
| | - Yu‐Jong Wu
- Scientific Research Division National Synchrotron Radiation Research Center Hsinchu Taiwan
- Department of Applied Chemistry National Yang Ming Chiao Tung University Hsinchu Taiwan
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Cardenuto MH, Cezar HM, Mikkelsen KV, Sauer SPA, Coutinho K, Canuto S. A QM/MM study of the conformation stability and electronic structure of the photochromic switches derivatives of DHA/VHF in acetonitrile solution. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 251:119434. [PMID: 33465576 DOI: 10.1016/j.saa.2021.119434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/30/2020] [Accepted: 01/03/2021] [Indexed: 06/12/2023]
Abstract
We present a detailed theoretical study of the electronic absorption spectra and thermochemistry of molecular photoswitches composed of one and two photochromic units of dihydroazulene (DHA)/vinylheptafulvene (VHF) molecules. Six different isomers are considered depending on the ring opening/closure forms of the DHA units. The solvent effect of acetonitrile is investigated using a sequential Molecular Mechanics/Quantum Mechanics approach. The thermochemical investigations of these photochromic molecules were performed using the Free Energy Perturbation method, and the simulations were performed using Configurational Bias Monte Carlo. We show that to open the 5-member ring of the DHA, there is no significant gain in thermal release of energy for the back reaction when a unit or two DHA units are considered. Overall, we found agreement between the solvation free energy based on Monte Carlo simulations and the continuum solvent model. However, the cavitation term in the continuum model is shown to be a source of disagreement when the non-electrostatic terms are compared. The electronic absorption spectra are calculated using TDDFT CAM-B3LYP/cc-pVDZ. Agreement with experiment is obtained within 0.1 eV, considering statistically uncorrelated configurations from the simulations. Inhomogeneous broadening is also considered and found to be well described in all cases.
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Affiliation(s)
- Marcelo Hidalgo Cardenuto
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, Cidade Universitária, 05508-090 São Paulo, Brazil
| | - Henrique M Cezar
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, Cidade Universitária, 05508-090 São Paulo, Brazil
| | - Kurt V Mikkelsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Stephan P A Sauer
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Kaline Coutinho
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, Cidade Universitária, 05508-090 São Paulo, Brazil.
| | - Sylvio Canuto
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, Cidade Universitária, 05508-090 São Paulo, Brazil.
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Cezar HM, Canuto S, Coutinho K. DICE: A Monte Carlo Code for Molecular Simulation Including the Configurational Bias Monte Carlo Method. J Chem Inf Model 2020; 60:3472-3488. [DOI: 10.1021/acs.jcim.0c00077] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Henrique M. Cezar
- Instituto de Fisica, Universidade de Sao Paulo, 05508-090 Sao Paulo, SP, Brazil
| | - Sylvio Canuto
- Instituto de Fisica, Universidade de Sao Paulo, 05508-090 Sao Paulo, SP, Brazil
| | - Kaline Coutinho
- Instituto de Fisica, Universidade de Sao Paulo, 05508-090 Sao Paulo, SP, Brazil
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Agapito F, Cabral BJC. Energetics of Radical Formation in Eumelanin Building Blocks: Implications for Understanding Photoprotection Mechanisms in Eumelanin. J Phys Chem A 2016; 120:10018-10022. [PMID: 28002950 DOI: 10.1021/acs.jpca.6b10122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest melanin building blocks are largely unknown. In order to address this fundamental issue, the bond dissociation enthalpies (BDEs) for the melanin monomers 5,6-dihydroxy-1H-indole-2-carboxylic acid (DHICA), 1H-indole-5,6-diol (DHI), and 1H-indole-5,6-dione (IQ) were determined through high-accuracy ab initio quantum chemistry methods. Our results provide strong evidence of the importance on BDEs for explaining the experimentally observed dependence of the antioxidant properties of eumelanin pigments on the DHICA/DHI ratio, and the role that these two species play on the photoprotection mechanism.
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Affiliation(s)
- Filipe Agapito
- Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa , 1749-016 Lisboa, Portugal
| | - Benedito J Costa Cabral
- Departamento de Química e Bioquímica and Grupo de Física Matemática, Faculdade de Ciências, Universidade de Lisboa , 1749-016 Lisboa, Portugal
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Zhang N, Ruan X, Song Y, Liu Z, He G. Molecular dynamics simulation of the hydration structure and hydrogen bonding behavior of phenol in aqueous solution. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.06.048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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8
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Kerzig C, Goez M. Photoionization access to cyclodextrin-encapsulated resveratrol phenoxy radicals and their repair by ascorbate across the phase boundary. Phys Chem Chem Phys 2016; 18:20802-11. [DOI: 10.1039/c6cp03742a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Photoionization with UV-A generates phenoxy radical ResO˙ of the famous red-wine antioxidant resveratrol inside cyclodextrin cavities without the participation of auxiliary reactants. This permits the isolated exploration of the ResO˙ repair by ascorbate at the water–cyclodextrin interface.
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Affiliation(s)
- Christoph Kerzig
- Martin-Luther-Universität Halle-Wittenberg
- Institut für Chemie
- D-06120 Halle (Saale)
- Germany
| | - Martin Goez
- Martin-Luther-Universität Halle-Wittenberg
- Institut für Chemie
- D-06120 Halle (Saale)
- Germany
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Torras J, Seabra GDM, Roitberg AE. A Multiscale Treatment of Angeli's Salt Decomposition. J Chem Theory Comput 2015; 5:37-46. [PMID: 26609819 DOI: 10.1021/ct800236d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sodium trioxodinitrate's (Na2N2O3, Angeli's salt) unique cardiovascular effects have been associated with its ability to yield HNO upon dissociation under physiological conditions. Due to its potential applications in new therapies for heart failure, the dissociation of Angeli's salt has recently received increased attention. The decomposition mechanism has been previously studied by quantum mechanical methods using a continuum approximation (PCM) for the solvent effects. In this work we use our recently developed interface of the Amber and Gaussian packages via the PUPIL package to study Angeli's salt dissociation in a hybrid QM/MM scheme where the water solvent molecules are treated explicitly with classical mechanics while the solute is treated with full quantum mechanics (UB3LYP/6-31+G(d) and UMP2/6-31+G(d)) level. Multiple steered molecular dynamics was used with the Jarzynski relationship to extract the free energy profile for the process. We obtain 4.8 kcal mol(-1) and 6.4 kcal mol(-1) free energy barriers for the N-N bond breaking for UB3LYP and UMP2, respectively. The geometries and Mulliken charges for reactant, transition state, and products have been characterized through a number of hybrid QM/MM molecular dynamics runs with the N-N distance restrained to representative values of each species. The results highlight the role of individual solvent molecules for the reaction energetics and provide a comparison point against implicit solvation methods.
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Affiliation(s)
- Juan Torras
- Departament d'Enginyeria Química, EUETII, Universitat Politècnica de Catalunya, Pça. Rei 15, 08700-Igualada, Spain, and Quantum Theory Project, Departments of Physics and of Chemistry, University of Florida, Gainesville, Florida 32611-8435
| | - Gustavo de M Seabra
- Departament d'Enginyeria Química, EUETII, Universitat Politècnica de Catalunya, Pça. Rei 15, 08700-Igualada, Spain, and Quantum Theory Project, Departments of Physics and of Chemistry, University of Florida, Gainesville, Florida 32611-8435
| | - Adrian E Roitberg
- Departament d'Enginyeria Química, EUETII, Universitat Politècnica de Catalunya, Pça. Rei 15, 08700-Igualada, Spain, and Quantum Theory Project, Departments of Physics and of Chemistry, University of Florida, Gainesville, Florida 32611-8435
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da Cunha AR, Duarte EL, Lamy MT, Coutinho K. Protonation/deprotonation process of Emodin in aqueous solution and pKa determination: UV/Visible spectrophotometric titration and quantum/molecular mechanics calculations. Chem Phys 2014. [DOI: 10.1016/j.chemphys.2014.06.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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11
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Swiatla-Wojcik D, Szala-Bilnik J. Mechanism of OH radical hydration: A comparative computational study of liquid and supercritical solvent. J Chem Phys 2012; 136:064510. [DOI: 10.1063/1.3683436] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Characterization and spectroscopic analysis of phenol–ethanol hydrogen bonded clusters. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.07.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Thermodynamic stability of hydrogen-bonded systems in polar and nonpolar environments. J Comput Chem 2010; 31:2046-55. [DOI: 10.1002/jcc.21491] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Sprynskyy M, Ligor T, Lebedynets M, Buszewski B. Kinetic and equilibrium studies of phenol adsorption by natural and modified forms of the clinoptilolite. JOURNAL OF HAZARDOUS MATERIALS 2009; 169:847-854. [PMID: 19423221 DOI: 10.1016/j.jhazmat.2009.04.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 04/06/2009] [Accepted: 04/06/2009] [Indexed: 05/27/2023]
Abstract
The contribution presents results of investigation of phenol adsorption by the raw, HDTMA- and NaOH-modified clinoptilolite. The experimental data on the sorption kinetic process are modelled using the particle and the film diffusion models with calculation of a rate constant of intraparticle mass transfer. Two main stages may be divided in the kinetic sorption process: (1) initial rapid sorption (amount of phenol sorbed 85-90%) extending over the first 60 min and (2) stage of slow approach to equilibrium covering about 8h. Equilibrium isotherms for phenol adsorption are modelled using the Langmuir, Freundlich and Dubinin-Radushkevich equations. The Freundlich isotherm describes in a greater degree phenol sorption from aqueous solutions of low phenol concentrations, while the Langmuir isotherm fits better to sorption at high initial concentrations.
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Affiliation(s)
- Myroslav Sprynskyy
- Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun,
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15
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Das TN. Hidden chemistry in phenoxyl radical (C6H5O•) coupling reaction mechanism revealed. J PHYS ORG CHEM 2009. [DOI: 10.1002/poc.1534] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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The Sequential qm/mm Method and its Applications to Solvent Effects in Electronic and Structural Properties of Solutes. CHALLENGES AND ADVANCES IN COMPUTATIONAL CHEMISTRY AND PHYSICS 2008. [DOI: 10.1007/978-1-4020-8270-2_7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Bakalbassis EG, Lithoxoidou AT, Vafiadis AP. Theoretical insights, in the liquid phase, into the antioxidant mechanism-related parameters in the 2-monosubstituted phenols. J Phys Chem A 2007; 110:11151-9. [PMID: 16986850 DOI: 10.1021/jp061718p] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The paper describes a DFT/B3LYP study, in the liquid phase, [using the PCM continuum model] on the O-H bond dissociation enthalpy (BDE) and ionization energy (IE) parameter values of the 2-monosubstituted phenols (2-X-ArOH), related to the H-atom transfer (HAT) and single-electron transfer (SET) mechanisms. The solvent and substituent effects on the conformers, the BDEs, and the IEs were studied using four electron-donating (EDG) and five electron-withdrawing (EWG) groups, in seven different solvents. In both the EDG- and/or EWG-substituted species of the parent compounds, radicals, and/or cation radicals, the most stable conformer is varied, depending on the medium and the substitution. The EWG-substituents increase IEs, resulting in a weaker antioxidant activity than the EDG ones; the effect appears stronger on the IEs than on BDEs. However, although the liquid-phase IEs, which are related to solution-phase oxidation potentials, decrease with the polarity and/or the hydrogen-bonding ability of the solvent, the opposite holds true for the BDEs, exhibiting a weaker effect. The gas-phase-calculated IE for benzene is among the most accurate ones in the field, compared to the experiment, that for phenol being the most accurate. In addition, calculated IEs for the 2-X-ArOH are in close agreement with the very few existing experimental ones. It is shown that the oxidation potentials are (a) highly correlated with the gas-phase ones, and (b) strongly solvent dependent. The stabilization/destabilization of the cation radical (SPC) contribution, in all media, is the decisive factor in the DeltaIE calculation. The reasonable correlations found between the DeltaBDE and DeltaIE could account well for the assumption of the simultaneous action of both mechanisms in the 2-X-ArOH, in both the gas and the liquid phase. It seems, however, that the presence of a particular solvent by itself is not sufficient enough for the HAT to SET transition. The involvement of specific ED and/or EW groups in the 2-X-ArOH seems also necessary. It appears that our theoretical approach is not only generally applicable to the set of substituents important to antioxidant activity but also useful in (a) the rational design of phenolic antioxidants and (b) affording accurate BDE and IE parameter values related to both possible antioxidant mechanisms.
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Affiliation(s)
- Evangelos G Bakalbassis
- Laboratory of Applied Quantum Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
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Aparicio S. Computational Study on the Properties and Structure of Methyl Lactate. J Phys Chem A 2007; 111:4671-83. [PMID: 17489567 DOI: 10.1021/jp070841t] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A theoretical study on the properties and molecular level structure of the very important green solvent methyl lactate is carried out in the gas phase and methanol and water solutions, with the solvent treated both explicitly and as a continuum. Torsional barriers giving rise to different conformers by rotation of the hydroxyl and methyl groups were analyzed using density functional theory (DFT) to establish the most stable conformer both in gas phase and solution. DFT computations on lactate dimers were also done to study short-range features, and the effect of the surrounding solvent on intra- and intermolecular hydrogen bonding was analyzed according to the polarizable continuum model approach. We have also studied lactate/water and lactate/methanol small clusters together with the corresponding binding energies. Moreover, classical molecular dynamics simulations (MD) were carried out to study medium- and large-range effects at lower computational cost. MD simulations at different pressure and temperature conditions on pure lactate were carried out, and mixtures with water and methanol of different compositions were also studied. Structural information, analyzed through the radial distribution functions, together with dynamic aspects of pure and mixed fluids were considered. The intramolecular hydrogen bonding ability of methyl lactate together with the possibility of homo- and hetero-intermolecular association determines the behavior of this molecule in pure fluids or in mixed.
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Affiliation(s)
- Santiago Aparicio
- Departamento de Química, Universidad de Burgos, 09001 Burgos, Spain.
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Mintz C, Clark M, Acree WE, Abraham MH. Enthalpy of Solvation Correlations for Gaseous Solutes Dissolved in Water and in 1-Octanol Based on the Abraham Model. J Chem Inf Model 2006; 47:115-21. [PMID: 17238256 DOI: 10.1021/ci600402n] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Data have been assembled on the enthalpies of solvation of 373 compounds in water and 138 compounds in 1-octanol. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental solvation enthalpies to within standard deviations of 3.68 kJ/mol (water) and 2.66 kJ/mol (1-octanol). The derived correlations provide very accurate mathematical descriptions of the observed enthalpies of solvation, which in the case of water span a range of 150 kJ/mol. Division of the experimental values into a training set and a test set shows that there is no bias in predictions and that the predictive capability of the correlations is better than 4 kJ/mol.
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Affiliation(s)
- Christina Mintz
- Department of Chemistry, P.O. Box 305070, University of North Texas, Denton, Texas 76203-5070, USA
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Phongtamrug S, Tashiro K, Miyata M, Chirachanchai S. Supramolecular Structure of N,N-Bis(2-hydroxybenzyl)alkylamine: Flexible Molecular Assembly Framework for Host without Guest and Host with Guest. J Phys Chem B 2006; 110:21365-70. [PMID: 17048966 DOI: 10.1021/jp061778v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
N,N-Bis(2-hydroxybenzyl)alkylamine derivatives form a cage-like assembly consisting of two molecules via inter- and intramolecular hydrogen bonds. The derivatives exhibit themselves as host to accept copper-ion guests under the double-oxygen-bridged dimeric system. Quantum chemical calculation suggested that the host-guest interaction is based on a charge-transfer coordination. Comparison of the crystal structures before and after complexation clarifies a rare example of a host-guest compound where the hosts maintain their cage framework through the change of hydrogen bonds to coordination bonds.
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Affiliation(s)
- Suttinun Phongtamrug
- The Petroleum and Petrochemical College, Chulalongkorn University, Phyathai Road, Pathumwan, Bangkok 10330, Thailand
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23
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Lima MCP, Coutinho K, Canuto S, Rocha WR. Reaction Mechanism and Tautomeric Equilibrium of 2-Mercaptopyrimidine in the Gas Phase and in Aqueous Solution: A Combined Monte Carlo and Quantum Mechanics Study. J Phys Chem A 2006; 110:7253-61. [PMID: 16737277 DOI: 10.1021/jp060821b] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A combined Monte Carlo and quantum mechanical study was carried out to analyze the tautomeric equilibrium of 2-mercaptopyrimidine in the gas phase and in aqueous solution. Second- and fourth-order Møller-Plesset perturbation theory calculations indicate that in the gas phase thiol (Pym-SH) is more stable than the thione (Pym-NH) by ca. 8 kcal/mol. In aqueous solution, thermodynamic perturbation theory implemented on a Monte Carlo NpT simulation indicates that both the differential enthalpy and Gibbs free energy favor the thione form. The calculated differential enthalpy is DeltaH(SH)(-->)(NH)(solv) = -1.7 kcal/mol and the differential Gibbs free energy is DeltaG(SH)(-->)(NH)(solv) = -1.9 kcal/mol. Analysis is made of the contribution of the solute-solvent hydrogen bonds and it is noted that the SH group in the thiol and NH group in the thione tautomers act exclusively as a hydrogen bond donor in aqueous solution. The proton transfer reaction between the tautomeric forms was also investigated in the gas phase and in aqueous solution. Two distinct mechanisms were considered: a direct intramolecular transfer and a water-assisted mechanism. In the gas phase, the intramolecular transfer leads to a large energy barrier of 34.4 kcal/mol, passing through a three-center transition state. The proton transfer with the assistance of one water molecule decreases the energy barrier to 17.2 kcal/mol. In solution, these calculated activation barriers are, respectively, 32.0 and 14.8 kcal/mol. The solvent effect is found to be sizable but it is considerably more important as a participant in the water-assisted mechanism than the solvent field of the solute-solvent interaction. Finally, the calculated total Gibbs free energy is used to estimate the equilibrium constant.
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Affiliation(s)
- Maria Carolina P Lima
- Departamento de Química Fundamental - CCEN, Universidade Federal de Pernambuco, Cidade Universitaria, Recife, PE, Brazil
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Cabral BC, Canuto S. Reply to comment on ‘The enthalpy of the O–H bond homolytic dissociation: Basis-set extrapolated density functional theory and coupled cluster calculations’. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.09.140] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Cabral BC, Canuto S. The enthalpy of the O–H bond homolytic dissociation: Basis-set extrapolated density functional theory and coupled cluster calculations. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.02.100] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Coutinho K, Cabral BC, Canuto S. Can larger dipoles solvate less? solute–solvent hydrogen bond and the differential solvation of phenol and phenoxy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.10.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Cabral do Couto P, Guedes RC, Costa Cabral BJ, Martinho Simões JA. The hydration of the OH radical: Microsolvation modeling and statistical mechanics simulation. J Chem Phys 2003. [DOI: 10.1063/1.1605939] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Guedes RC, Coutinho K, Costa Cabral BJ, Canuto S, Correia CF, Borges dos Santos RM, Martinho Simões JA. Solvent Effects on the Energetics of the Phenol O−H Bond: Differential Solvation of Phenol and Phenoxy Radical in Benzene and Acetonitrile. J Phys Chem A 2003. [DOI: 10.1021/jp035912c] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. C. Guedes
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - Kaline Coutinho
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - B. J. Costa Cabral
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - Sylvio Canuto
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - C. F. Correia
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - R. M. Borges dos Santos
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
| | - J. A. Martinho Simões
- Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal, Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa, Portugal, Universidade de Mogi das Cruzes, CP 411, 08701-970 Mogi das Cruzes, São Paulo, Brazil, Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo, Brazil, and Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8005
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