Molecular basis of quantitative structure-properties relationships (QSPR):A quantum similarity approach

Since the dawn of quantitative structure-properties relationships (QSPR), e mpirical parameters related to structural, electronic and hydrophobic molec ular properties have been used as molecular descriptors to determine such r elationships. Among all these parameters, Hammett sigma constants and the l ogarithm of the octanol-water partition coefficient, log P, have been massi vely employed in QSPR studies. In the present paper, a new molecular descri ptor, based on quantum similarity measures (QSM), is proposed as a general substitute of these empirical parameters. This work continues previous anal yses related to the use of QSM to QSPR, introducing molecular quantum selfs imilarity measures (MQS-SM) as a single working parameter in some cases. Th e use of MQS-SM as a molecular descriptor is first confirmed from the corre lation with the aforementioned empirical parameters. The Hammett equation h as been examined using MQS-SM for a series of substituted carboxylic acids. Then, for a series of aliphatic alcohols and acetic acid esters, log P val ues have been correlated with the self-similarity measure between density f unctions in water and octanol of a given molecule. And finally, some exampl es and applications of MQS-SM to determine QSAR are presented. In all studi ed cases MQS-SM appeared to be excellent molecular descriptors usable in ge neral QSPR applications of chemical interest.