Infrared spectra information and their correlation with QSAR descriptors

In principle, the InfraRed (IR) spectra have very appealing properties for QSAR research: they are generated in the range of low energy molecular inte ractions that play a fundamental role in life (e.g., for molecular recognit ion), and they are extremely specific fingerprints of the molecules. We com pared the information carried by the fingerprint region of the IR spectra ( 1500-600 cm(-1)) with that of a range of descriptors presently in use in th e QSAR field: (a) classical physical chemical and quantum mechanical proper ties (logP, MR, HOMO, LUMO); (b) molecular connectivities; (c) 2-D molecula r distances; and (d) a novel infrared range vibration based theoretical des criptor (EVA). Much redundancy and overlapping was found among descriptors such as connectivities, 2-D distances, and theoretical spectral EVA descrip tors. On the contrary, the complex information carried by IR spectra (finge rprint region) was markedly different from that codified in various molecul ar descriptors presently in use in QSAR practice, thus pointing to the impo rtance of further studying the potential relevance of IR information for QS AR analysis.