THE AIBLHiCoS METHOD: PREDICTING AQUEOUS pKa VALUES FROM GAS PHASE EQUILIBRIUM BOND LENGTHS

UoM administered thesis: Master of Philosophy

  • Authors:
  • Cate Anstoter

Abstract

The proposed AIBLHiCoS method predicts a given compound's pKa in aqueous solution, from a single ab initio bond length only, after geometry-optimisation in the gas phase. The methodology builds upon work done by the Popelier group previously, which established that a single 'active bond length' had high correlation with experimental pKa values. Previously the phenol family was studied, this work provided the foundations for the work within this report on the chemically similar family of the naphthols.Here we provide simple and predictive equations for naphthols and chemically similar biomolecules. Each linear equation corresponds to a High-Correlation Subset (HiCoS), which expresses the novel type of linear free energy relationship (LFER) discovered here. The naphthol family exhibits a clear and strong relationship with the phenol family, with the "active" C-O bond always producing the highest correlations.A number of different levels of theory were explored in order to ensure the correlations found were rigorously well defined. To provide the greatest insight into the AIBLHiCoS method the details of data procurement and analysis are given.The proposed method can isolate erroneous experiments, operate in non-aqueous solution, and at different temperatures. Moreover, the existence of 'active fragments' is demonstrated in a variety of sizeable biomolecules for which the pKa is successfully predicted, and often better than by commercial packages currently employed.

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Original languageEnglish
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Award date1 Aug 2016