Original Paper

Molecular modeling annual

, Volume 8, Issue 4, pp 95-101

First online:

A QSPR-Approach to the Estimation of the pK HB of Six-Membered Nitrogen-Heterocycles using Quantum Mechanically Derived Descriptors

  • Matthias HennemannAffiliated withComputer-Chemie-Centrum der Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91054 Erlangen, Germany. E-mail: clark@chemie.uni-erlangen.de Phone: +49-9131-8522948 Fax: +49-9131-8526565
  • , Timothy ClarkAffiliated withComputer-Chemie-Centrum der Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91054 Erlangen, Germany. E-mail: clark@chemie.uni-erlangen.de Phone: +49-9131-8522948 Fax: +49-9131-8526565

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Abstract.

Descriptors derived from semiempirical (AM1) molecular orbital calculations have been used to construct a quantitative structure-property relationship (QSPR) for the thermodynamic hydrogen-bond basicity, pK HB, of a series of six-membered aromatic nitrogen-heterocycles. The resulting model uses four-descriptors (the Coulson charge on the nitrogen atom, the energy of the localized nitrogen lone-pair orbital, the p-orbital contribution to this MO and an accessibility angle). The model gives r2 cv=0.95 for 51 compounds with a standard deviation between calculation and experiment of 0.13 log units.

Keywords. pKHB– Hydrogen bonding – QSPR – AM1