Molecular Topology and Quantum Chemical Descriptors in the Study of Reversed-Phase Liquid Chromatography. Hydrogen-Bonding Behavior of Chalcones and Flavanones

The reversed-phase liquid chromatographic hydrophobicity parameters (log K′w and S) of several chalcones and flavanones were determined with methanol:water mobile phases of different compositions and with trace quantities of n-decylamine and 1-octanol added to the eluent to minimize the silanophilic interactions present in alkylsilane-bonded phases. It has been reported that qualitative hydrogen bonding information can be obtained from the relationship between S and log K′w determined with these chromatographic conditions. To quantitatively describe the hydrogen-bonding discrimination effects observed for the compounds under study, the parameter Δ was defined as follows: Δ(s–log Kw). With topological and molecular orbital calculations, several molecular descriptors were computed for test compounds, and multivariate statistical techniques were used to examine the informative value of the parameter proposed. The results obtained indicate that Δ(s–log Kw) encodes structural information mainly related to the molecular polarity and the ability of compounds to participate in hydrogen-bonding interactions. Similar structural information was also obtained for Δ(s–log Kw) values of 31 structurally dissimilar compounds.