OPTIMAL CHARACTERIZATION OF STRUCTURE FOR PREDICTION OF PROPERTIES

Different topological and physicochemical parameters have been used to predict hydrophobicity (log P, octanol-water) of chemicals. We calculated a hydrogen bonding parameter (HB1) and a large number of molecular connectivity and complexity indices for a diverse set of 382 molecules. It is known from earlier studies that topological indices (TIs) predict properties of congeneric sets reasonably well. Since HB1 is an approximate quantifier of hydrogen bonding and has integral values, we used HB1 to classify the diverse set into strongly and weakly hydrogen bonding subsets. In an attempt to examine the utility of TIs in predicting properties of relatively similar groups of molecules, we carried out a correlation of log P with TIs for a subset (n = 139) of the original diverse set (n = 382) with a weak hydrogen bonding ability (HB1 = 0). Results show that TIs give a better predictive model for the more homogeneous subset as compared to the diverse set of molecules.