## Abstract

The absolute pK_{a} values of 24 representative amine compounds, including cocaine, nicotine, 10 neurotransmitters, and 12 anilines, in aqueous solution were calculated by performing first-principles electronic structure calculations that account for the solvent effects using four different solvation models, i.e., the surface and volume polarization for electrostatic interaction (SVPE) model, the standard polarizable continuum model (PCM), the integral equation formalism for the polarizable continuum model (IEFPCM), and the conductor-like screening solvation model (COSMO). Within the examined computational methods, the calculations using the SVPE model lead to the absolute pK_{a} values with the smallest root-mean-square-deviation (rmsd) value (1.18). When the SVPE model was replaced by the PCM, IEFPCM, and COSMO, the rmsd value of the calculated absolute pK_{a} values became 3.21, 2.72, and 3.08, respectively. All types of calculated pK_{a} values linearly correlate with the experimental pK_{a} values very well. With the empirical corrections using the linear correlation relationships, the theoretical pK_{a} values are much closer to the corresponding experimental data and the rmsd values become 0.51-0.83. The smallest rmsd value (0.51) is also associated with the SVPE model. All of the results suggest that the first-principles electronic structure calculations using the SVPE model are a reliable approach to the pKa prediction for the amine compounds.

Original language | English |
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Pages (from-to) | 10599-10605 |

Number of pages | 7 |

Journal | Journal of Physical Chemistry B |

Volume | 111 |

Issue number | 35 |

DOIs | |

State | Published - Sep 6 2007 |

## ASJC Scopus subject areas

- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry

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