GRAPHICAL BOND ORDERS - NOVEL STRUCTURAL DESCRIPTORS

We outline an algorithm for construction of novel molecular descriptor s from known structural invariants or molecular properties viewed as d escriptors. The novel descriptors are bond-additive quantities derived by assigning to each bond a contribution x' obtained by evaluating in variant X for graph G'-e, which is attained from graph G (representing a given molecule) by deleting edge e. The molecular descriptor X'/X i s obtained as a normalized sum of bond contributions, where X' is equa l to the sum of bond orders x'. The approach is illustrated by present ing X'/X descriptors for smaller alkanes for several well-known topolo gical indices, including the connectivity index, Hosoya's Z index, the Wiener index, and others. The algorithm is quite general and allows o ne to include molecular properties as source data for the construction of novel descriptors. This is particularly important in view of a lim ited number of properties used as descriptors in traditional quantitat ive structure-activity studies. The new algorithm literally doubles th e number of descriptors available to traditional chemometricians in th eir quest for novel property-activity relationships.