Avoiding gas-phase calculations in theoretical pKa predictions.

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dc.contributor.author Casasnovas Perera, Rodrigo
dc.contributor.author Fernández Payeras, David
dc.contributor.author Ortega Castro, Joaquín
dc.contributor.author Frau Munar, Juan
dc.contributor.author Donoso Pardo, Josefa Laurentina
dc.contributor.author Muñoz Izquierdo, Francisco
dc.date.accessioned 2018-10-26T13:15:59Z
dc.identifier.uri http://hdl.handle.net/11201/148298
dc.description.abstract [eng] CBS-QB3, two simplified and less computationally demanding versions of CBS-QB3, DFT-B3LYP, and HF quantum chemistry methods have been used in conjunction with the CPCM continuum solvent model to calculate the free energies of proton exchange reactions in water solution following an isodesmic reaction approach. According to our results, the precision of the predicted pK a values when compared to experiment is equivalent to that of the thermodynamic cycles that combine gas-phase and solution-phase calculations. However, in the aqueous isodesmic reaction schema, the accuracy of the results is less sensitive to the presence of explicit water molecules and to the global charges of the involved species since the free energies of solvation are not required. In addition, this procedure makes easier the prediction of pK a values for molecules that undergo large conformational changes in solvation process and makes possible the pK a prediction of unstable species in gas-phase such as some zwitterionic tautomers. The successive pK a values of few amino acids corresponding to the ionization of the α-carboxylic acid and α-amine groups, which is one of the problematic cases for thermodynamic cycles, were successfully calculated by employing the aqueous isodesmic reaction yielding mean absolute deviations of 0.22 and 0.19 pK a units for the first and second ionization processes, respectively.
dc.format application/pdf
dc.relation.isformatof Versió postprint del document publicat a: https://doi.org/10.1007/s00214-011-0945-5
dc.relation.ispartof Theoretical Chemistry Accounts, 2011, vol. 130, p. 1-13
dc.subject.classification 54 - Química
dc.subject.other 54 - Chemistry. Crystallography. Mineralogy
dc.title Avoiding gas-phase calculations in theoretical pKa predictions.
dc.type info:eu-repo/semantics/article
dc.type info:eu-repo/semantics/acceptedVersion
dc.date.updated 2018-10-26T13:15:59Z
dc.date.embargoEndDate info:eu-repo/date/embargoEnd/2075-01-01
dc.embargo 2075-01-01
dc.subject.keywords pKa calculations
dc.subject.keywords Chemical Kinetics
dc.subject.keywords Cálculos teóricos
dc.subject.keywords físico-química
dc.subject.keywords isodesmic reaction
dc.rights.accessRights info:eu-repo/semantics/embargoedAccess
dc.identifier.doi https://doi.org/10.1007/s00214-011-0945-5

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