Optimum Structural Descriptors Derived from the Ivanciuc- Balaban Operator #
BioChem Press, Ovidiu Ivanciuc, Teodora Ivanciuc, T Alexandru · 2002
Topological indices represent an important class of structural descriptors, widely used in developing structure– property models, in drug design, virtual synthesis, similarity and diversity assessment. Because there is a considerable interest in deriving additional topological indices for QSPR and QSAR models, we introduce in this paper an extended Ivanciuc–Balaban operator. We consider that the exponent –1/2 used in the standard formula of this operator may not be the optimum for modeling some molecular properties, and we now define a new formula containing an adjustable exponent that is optimized for each investigated property. The Ivanciuc– Balaban structural descriptors were computed for 134 alkanes C6–C10 from seven molecular matrices, namely adjacency A, distance D, reciprocal distance RD, distance–path Dp, reciprocal distance–path RDp, path Szeged Szp, and reciprocal path Szeged RSzp matrix. Structural descriptors derived from the new operator were tested in QSPR studies for several alkane properties and we found that in most cases the optimum value of the exponent is different from –1/2.