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A density functional study on the p K a of small polyprotic molecules
Author(s) -
Baba Takeshi,
Matsui Toru,
Kamiya Katsumasa,
Nakano Masayoshi,
Shigeta Yasuteru
Publication year - 2014
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.24631
Subject(s) - deprotonation , protonation , chemistry , molecule , polarizable continuum model , computational chemistry , aqueous solution , density functional theory , organic chemistry , solvation , ion
The p K a values of several biologically important small molecules in aqueous solution, such as salicylic acid, histamine, and dopamine, were determined by density functional theory combined with the polarizable continuum model, which has been proposed for predicting p K a values of nucleic acids and proteins. These molecules have plural protonation sites and the inherent p K a determines which protons exist at a specific pH. Taking into account the ensemble average, and that the order of the deprotonation steps is specific among several possible pathways, it emerged that the calculated p K a values mostly reproduced the experimental ones within an error of ± 1.0 p K a units. © 2014 Wiley Periodicals, Inc.