ABSTRACT
Virginia Commonwealth University, Richmond, VA 23298, USA
The molecular connectivity chi indices encode aspects of molecular structure for a whole molecule. Each index is a sum of weighted subgraphs in which the weights are functions of the molecular connectivity delta values. The simple delta value is a sigma electron parameter and the valence delta value is a valence electron parameter. The development of the chi indices is presented and illustrated. Several examples are given in which the chi indices are the basis for sound QSAR and QSPR models. The chi indices have also been used to invert QSAR equations to determine molecular structures which are predicted to possess activity values in a desired range. Several fundamental relations on molecular structure are presented. The role of chi indices in molecular similarity is discussed and the possibility for useful database searching is also presented.
