Reactivity descriptors for the hydrogen bonding ability of pyridine bases

The hydrogen bonding interaction between pyridine bases and water was theoretically studied by applying density functional theory computations at the B3LYP/631G(d,p) level. The theoretically determined binding energies for the complexation process correlate well with the experimental solvatochromic parameters beta for the respective bases. A very good linear relationship was also found between the evaluated binding energies of hydrogen bond formation and the respective electrostatic potential at nuclei (EPN) values at the pyridine nitrogen atom. It was found that the theoretical EPN values correlated linearly with the beta constants and the quantities could be employed as alternative. It was concluded that the electrostatic potential at nuclei characterized quantitatively the reactivity of the studied molecules toward the hydrogen bond formation. EPN values could be applied as hydrogen bond descriptors in QSAR studies.