Aspects of oxopyridine-water interactions

The hydration schemes of the lactam and lactim tautomers of 2- and 4-hydroxypyridines have been established by appropriate electrostatic calculations. It is shown that hydration stabilizes more of the lactam than the lactim tautomers of these molecules. Ab initio SCF MO calculations performed for the complex of 4-pyridone with water show that the binding energies for water situated out of the plane of pyridone are smaller than when water is placed in the plane of the molecule. The comparison of the ab initio results with earlier CNDO/2 ones shows that the latter greatly overestimate the stability of the nonplanar complexes.