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Donald G Truhlar - One of the best experts on this subject based on the ideXlab platform.
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extension of a temperature dependent aqueous Solvation model to compounds containing nitrogen fluorine chlorine bromine and sulfur
Journal of Physical Chemistry B, 2008Co-Authors: Adam C Chamberlin, Christopher J Cramer, Donald G TruhlarAbstract:Most methods for predicting free energies of Solvation have been developed or validated exclusively for room temperature. Recently, we developed a model called SM6T for predicting aqueous Solvation free energies as a function of temperature for solutes composed of C, H, or O, and here we present Solvation model 8 with temperature dependence (SM8T) for predicting the temperature dependence of aqueous free energies of Solvation for compounds containing H, C, N, O, F, S, Cl, and Br in the range 273−373 K. We also describe the database of experimental aqueous free energies of Solvation used to parametrize the model. SM8T partitions the temperature dependence of the free energy of Solvation into two components: the temperature dependence of the bulk electrostatic contribution to the free energy of Solvation, which is computed using the generalized Born equation, and the temperature dependence of first-Solvation-shell effects, which is modeled by terms proportional to the solvent-exposed surface areas of atoms...
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single ion Solvation free energies and the normal hydrogen electrode potential in methanol acetonitrile and dimethyl sulfoxide
Journal of Physical Chemistry B, 2007Co-Authors: Casey P Kelly, Christopher J Cramer, Donald G TruhlarAbstract:The division of thermodynamic Solvation free energies of electrolytes into contributions from individual ionic constituents is conventionally accomplished by using the single-ion Solvation free energy of one reference ion, conventionally the proton, to set the single-ion scales. Thus, the determination of the free energy of Solvation of the proton in various solvents is a fundamental issue of central importance in solution chemistry. In the present article, relative Solvation free energies of ions and ion−solvent clusters in methanol, acetonitrile, and dimethyl sulfoxide (DMSO) have been determined using a combination of experimental and theoretical gas-phase free energies of formation, solution-phase reduction potentials and acid dissociation constants, and gas-phase clustering free energies. Applying the cluster pair approximation to differences between these relative Solvation free energies leads to values of −263.5, −260.2, and −273.3 kcal/mol for the absolute Solvation free energy of the proton in me...
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sm6 a density functional theory continuum Solvation model for calculating aqueous Solvation free energies of neutrals ions and solute water clusters
Journal of Chemical Theory and Computation, 2005Co-Authors: Casey P Kelly, Christopher J Cramer, Donald G TruhlarAbstract:A new charge model, called Charge Model 4 (CM4), and a new continuum solvent model, called Solvation Model 6 (SM6), are presented. Using a database of aqueous Solvation free energies for 273 neutrals, 112 ions, and 31 ion−water clusters, parameter sets for the mPW0 hybrid density functional of Adamo and Barone (Adamo, C.; Barone, V. J. Chem. Phys. 1998, 108, 664−675) were optimized for use with the following four basis sets: MIDI!6D, 6-31G(d), 6-31+G(d), and 6-31+G(d,p). SM6 separates the observable aqueous Solvation free energy into two different components: one arising from long-range bulk electrostatic effects and a second from short-range interactions between the solute and solvent molecules in the first Solvation shell. This partition of the observable Solvation free energy allows SM6 to effectively model a wide range of solutes. For the 273 neutral solutes in the test set, SM6 achieves an average error of ∼0.50 kcal/mol in the aqueous Solvation free energies. For solutes, especially ions, that hav...
Mikhail A Varfolomeev - One of the best experts on this subject based on the ideXlab platform.
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group additivity approach for determination of Solvation enthalpies of aromatic compounds in 1 butyl 3 methylimidazolium tetrafluoroborate based on solution calorimetry data
Journal of Molecular Liquids, 2017Co-Authors: Artashes A Khachatrian, Ziliya I Shamsutdinova, Mikhail A VarfolomeevAbstract:Abstract In this work thermochemistry of Solvation of mono-, di-, tri- and tetra-substituted benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]) ionic liquid was studied. Enthalpies of solution at infinite dilution of 34 substituted benzenes in [BMIM][BF 4 ] were measured at 298.15 K using solution calorimetry technique. Based on the experimental and literature data enthalpies of Solvation of 36 substituted benzenes in [BMIM][BF 4 ] were calculated. It was shown that enthalpies of Solvation of substituted benzenes in [BMIM][BF 4 ] are independent on the mutual position of subtituents and dipole moment of molecules. Group contribution scheme for prediction of enthalpies of Solvation of substituted benzenes was applied. Values of methyl- (CH 3 ), tert -butyl- ( tert -C 4 H 9 ), bromo- (Br), iodo- (I), amino- (NH 2 ), methoxy- (OCH 3 ), dimethylamino- (N(CH 3 ) 2 ), methylcarboxylate- (COOCH 3 ) group contributions to the enthalpies of Solvation in [BMIM][BF 4 ] were derived and compared with molecular solvents. Solvation enthalpies of substituted benzenes in [BMIM][BF 4 ] calculated through group contribution scheme were in good agreement with experimental data.
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enthalpies of solution and enthalpies of Solvation of chloro and nitro substituted benzenes in 1 butyl 3 methyl imidazolium based ionic liquids at 298 15k additivity of group contributions
Thermochimica Acta, 2016Co-Authors: Artashes A Khachatrian, Ziliya I Shamsutdinova, Mikhail A VarfolomeevAbstract:Abstract In this work thermochemistry of solution and Solvation of mono- and di-substituted chloro- and nitro-benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][TfO]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquids was studied. Enthalpies of solution at infinite dilution of benzene, chlorobenzene, nitrobenzene, 1,2-, 1,3-, 1,4-dichlorobenzenes, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1-chloro-2-nitrobenzene, 1-chloro-3-nitrobenzene, and 1-chloro-4-nitrobenzene in three ionic liquids were measured at 298.15 K. On the basis of experimental data enthalpies of Solvation of substituted benzenes in ionic solvents were calculated. Values of Cl and NO2 group contributions to the enthalpies of Solvation were derived and compared with molecular solvents. Enthalpies of Solvation of each series of dichlorobenzenes, chloronitrobenzenes and dinitrobenzenes in studied ionic liquids are equal and do not depend on the mutual position of substituents. This fact shows that dipole moment does not affect the enthalpy of Solvation of organic solutes in ionic liquids. Enthalpies of Solvation of disubstituted benzenes in ionic liquids calculated through group contribution approach were in good agreement with experimental data.
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new method for determination of vaporization and sublimation enthalpy of aromatic compounds at 298 15k using solution calorimetry technique and group additivity scheme
Thermochimica Acta, 2015Co-Authors: Boris N Solomonov, Mikhail A Varfolomeev, Vladimir B. Novikov, Ruslan N. Nagrimanov, Aleksey V Buzyurov, Yulia V Fedorova, Timur A. MukhametzyanovAbstract:Abstract In this work a new method for determination of vaporization/sublimation enthalpies of aromatic compounds directly at T = 298.15 K was developed. This method is based on the general relationship between vaporization/sublimation enthalpy and enthalpies of solution and Solvation of the studied compound in any solvent. According to this method the procedure for determination of vaporization (liquids) or sublimation (solids) enthalpy includes measurement of the solution enthalpy of the compound in a selected solvent and calculation of the Solvation enthalpy for this system. A group-additivity scheme for calculation of Solvation enthalpies is proposed. The Solvation enthalpy of compound is estimated from the Solvation enthalpy of parent aromatic or heteroaromatic compound and contributions of the substituent groups. Limiting solution enthalpies of 34 aromatic compounds (substituted benzenes, naphthalenes, biphenyls, pyrene, anthracene and pyridines) in carbon tetrachloride, benzene, acetonitrile and N,N-dimethylformamide were measured in the present work at 298.15 K. Vaporization/sublimation enthalpies of 78 aromatic and heteroaromatic compounds were determined directly at 298.15 K using experimentally measured solution enthalpies and predicted values of Solvation enthalpies. The results are in good agreement with available literature data.
Peter A. Kollman - One of the best experts on this subject based on the ideXlab platform.
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Solvation Model Based on Weighted Solvent Accessible Surface Area
The Journal of Physical Chemistry B, 2001Co-Authors: Junmei Wang, Wei Wang, Shuanghong Huo, And Matthew Lee, Peter A. KollmanAbstract:We have developed a fast procedure to predict Solvation free energies for both organic and biological molecules. This Solvation model is based on weighted solvent accessible surface area (WSAS). Least-squares fittings have been applied to optimize the weights of SAS for different atom types in order to reproduce the experimental Solvation free energies. Good agreement with experimental results has been obtained. For the 184-molecule set (model I), for which there are experimental Solvation free energies in 1-octanol, we have achieved an average error of 0.36 kcal/mol, better than that of the SM5.42R universal Solvation model1 by Li et al. For the 245-molecule set (model II) that has experimental aqueous Solvation free energies, our WSAS model achieves an average error of 0.48 kcal/mol, marginally larger than that of Li's model (0.46 kcal/mol). We have used a 401-molecule set, the largest training set (model IV) that we know of Solvation model development, to derive the SAS weights in order to reproduce th...
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Solvation Free Energies of Amides and Amines: Disagreement between Free Energy Calculations and Experiment
Journal of the American Chemical Society, 1995Co-Authors: Pierre-yves Morgantini, Peter A. KollmanAbstract:We present molecular dynamidfree energy calculations on the molecules acetamide, N-methylacetamide, N,N-dimethylacetamide, ammonia, methylamine, dimethylamine, and trimethylamine. Unlike the experimental data, which suggest a very non-additive Solvation free energy (N-methylacetamide and methylamine having the most negative free energy of Solvation), the calculations all find that the free energy of Solvation monotonically increases as a function of methyl addition. The disagreement with experiment is surprising, given the very good agreement (within 0.5 kcaYmo1) with experiment for calculation of the Solvation free energy of methane, ethane, propane, water, methanol, and dimethyl ether.
Christopher J Cramer - One of the best experts on this subject based on the ideXlab platform.
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extension of a temperature dependent aqueous Solvation model to compounds containing nitrogen fluorine chlorine bromine and sulfur
Journal of Physical Chemistry B, 2008Co-Authors: Adam C Chamberlin, Christopher J Cramer, Donald G TruhlarAbstract:Most methods for predicting free energies of Solvation have been developed or validated exclusively for room temperature. Recently, we developed a model called SM6T for predicting aqueous Solvation free energies as a function of temperature for solutes composed of C, H, or O, and here we present Solvation model 8 with temperature dependence (SM8T) for predicting the temperature dependence of aqueous free energies of Solvation for compounds containing H, C, N, O, F, S, Cl, and Br in the range 273−373 K. We also describe the database of experimental aqueous free energies of Solvation used to parametrize the model. SM8T partitions the temperature dependence of the free energy of Solvation into two components: the temperature dependence of the bulk electrostatic contribution to the free energy of Solvation, which is computed using the generalized Born equation, and the temperature dependence of first-Solvation-shell effects, which is modeled by terms proportional to the solvent-exposed surface areas of atoms...
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single ion Solvation free energies and the normal hydrogen electrode potential in methanol acetonitrile and dimethyl sulfoxide
Journal of Physical Chemistry B, 2007Co-Authors: Casey P Kelly, Christopher J Cramer, Donald G TruhlarAbstract:The division of thermodynamic Solvation free energies of electrolytes into contributions from individual ionic constituents is conventionally accomplished by using the single-ion Solvation free energy of one reference ion, conventionally the proton, to set the single-ion scales. Thus, the determination of the free energy of Solvation of the proton in various solvents is a fundamental issue of central importance in solution chemistry. In the present article, relative Solvation free energies of ions and ion−solvent clusters in methanol, acetonitrile, and dimethyl sulfoxide (DMSO) have been determined using a combination of experimental and theoretical gas-phase free energies of formation, solution-phase reduction potentials and acid dissociation constants, and gas-phase clustering free energies. Applying the cluster pair approximation to differences between these relative Solvation free energies leads to values of −263.5, −260.2, and −273.3 kcal/mol for the absolute Solvation free energy of the proton in me...
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sm6 a density functional theory continuum Solvation model for calculating aqueous Solvation free energies of neutrals ions and solute water clusters
Journal of Chemical Theory and Computation, 2005Co-Authors: Casey P Kelly, Christopher J Cramer, Donald G TruhlarAbstract:A new charge model, called Charge Model 4 (CM4), and a new continuum solvent model, called Solvation Model 6 (SM6), are presented. Using a database of aqueous Solvation free energies for 273 neutrals, 112 ions, and 31 ion−water clusters, parameter sets for the mPW0 hybrid density functional of Adamo and Barone (Adamo, C.; Barone, V. J. Chem. Phys. 1998, 108, 664−675) were optimized for use with the following four basis sets: MIDI!6D, 6-31G(d), 6-31+G(d), and 6-31+G(d,p). SM6 separates the observable aqueous Solvation free energy into two different components: one arising from long-range bulk electrostatic effects and a second from short-range interactions between the solute and solvent molecules in the first Solvation shell. This partition of the observable Solvation free energy allows SM6 to effectively model a wide range of solutes. For the 273 neutral solutes in the test set, SM6 achieves an average error of ∼0.50 kcal/mol in the aqueous Solvation free energies. For solutes, especially ions, that hav...
And Wei Zhang - One of the best experts on this subject based on the ideXlab platform.
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Empirical Aqueous Solvation Models Based on Accessible Surface Areas with Implicit Electrostatics
The Journal of Physical Chemistry B, 2002Co-Authors: Tingjun Hou, Xuebin Qiao, And Wei ZhangAbstract:In the current work, an empirical Solvation model based on accessible surface areas was reported, which can be used to predict the Solvation free energies for both organic and biological molecules very fast. This Solvation model is based on atom-weighted solvent accessible surface area (SAWSA). The parameterization procedure for different kinds of atoms was performed as follows: first, the atoms in a molecule were defined to different atom types based on SMARTS language; then the solvent accessible surface area for each atom (or charged group) was calculated; finally, a genetic algorithm (GA) was applied to optimize the Solvation parameters for different atom types in order to reproduce the experimental Solvation free energies. The derived model possessed promising predictive ability as indicated by the good statistical significance and good prediction on the external test set. Using the Solvation model based on all 377 neutral molecules, we have achieved an average unsigned error of 0.51 kcal/mol and st...
