A computational study of hydrogen bonding complexes between 1,2,3-triazine and water

The hydrogen-bonded complexes between 1,2,3-triazine and water have been studied using density functional theory, second-order Moller-Plesset perturbation theory and complete-active-space self-consistent-field methods. For the 1,2,3-triazine-H2O complex, our calculations predicted two comparably stable hydrogen bonding formations with the water molecule interacting to the axis nitrogen and to the off-axis nitrogen of 1,2,3-triazine, respectively. In the lowest 1(n, π*) excited state, only the off-axis structure is found. This prediction of a ground-state like excited-state structure arises due to localization of the excitation on the central nitrogen; it presents a distinctly different paradigm for excited state hydrogen bonding than has been previously identified.