Prediction of physical and chemical properties by quantitative structure - property relationships

THE PHYSICAL AND chemical properties of a compound are a function of its molecular structure. Structure-property relationships are developed by finding one or more molecular descriptors that explain variations in the physical or chemical properties of a group of congeners/analogs. While some descriptors can be determined experimentally, deriving them from either the two-dimensional (2-D) or three-dimensional (3-D) molecular structure is generally more convenient and practical. A relationship, once quantified, can be used to estimate the properties of other molecules simply from their structures and without the need for experimental determination or synthesis. This has resulted in the development of quantitative structureproperty relationships (QSPRs)’ as an important tool in chemical, biological, and environmental research. When a structure-property relationship is found, it may also provide insight into which aspect of the molecular structure influences the property. Such insight can facilitate a systematic approach to the design of new molecules with more desirable properties. When applied to biologically active molecules such as drugs, QSPR is usually referred to as a quantitative structure-activity relationship (QSAR). Many commercial software packages are available for determining QSPRs and QSARs, including modules for structure input and for the calculation of physical, chemical, and electronic descriptors.