Investigation of the relationships between logP and various chromatographic indices for a series of substituted coumarins. Evaluation of their similarity/dissimilarity using multivariate statistics

High Performance Liquid Chromatography and Reversed Phase Thin Layer Chromatography were applied in a series of substituted coumarins, in the aim to evaluate the conformity of the retention data with octanol water partition coefficients. The investigated compounds contain substituted amidoximes, or substituted heterocycles directly attached to the coumarinic skeleton. The interrelationships between the extrapolated capacity factors logk(w) and R-Mw the corresponding slopes S-HPLC, S-TLC and the Chromatographic Indices rho(oHPLC), rho(oTLC), as well as their correlation with logP were established. Conformation effects, concerning particularly molecules with planar structures, were found to interfere in retention, leading to deviations from the partition mechanism in both RP-TLC and HPLC. Moreover, HPLC appeared to be more sensitive to secondary effects in retention. The similarities/dissimilarities between logP and the various chromatographic indices at a more fundamental molecular level were further investigated by means of multivariate data analysis using calculated molecular descriptors.