Analysis of structural characteristics of chemical compounds in a large computer-based file. Part III. Statistical association of fragment incidence

Abstract

The statistical association of the incidence of some pairs of bond- and atom-centred structural fragments has been investigated in a sample of chemical structures from the Chemical Abstracts Service Registry System. Both positive and negative values of the association coefficient have been found, and in general, association is small between atoms but larger between simple pairs, bonded pairs, and augmented atoms. The performance of a structural fragment as a screen in substructure searching is affected by association.