Descriptors of the chemical structures

Abstract

Descriptors of the chemical structures are used to characterize and quantify properties of the entire molecules or relevant substructural fragments or the physical or chemical properties of the substances. The quantitative descriptors are based on the molecular structures as represented by constitutional formulas, hence an unambiguous definition of the structures is required, also with regard to the geometry, conformation, isomerism, tautomerism, stereochemistry, etc. The structural descriptors in a QSAR model have to represent the entire spectrum of the molecular or submolecular interactions leading to a particular property (i.e. hydrophobic, polar, electrostatic and steric interactions). Preferably, they should reflect the rate-limiting processes that are involved in producing the activity investigated. More than 200 different parameters have been reported (Dearden, 1990).