DFT study of hydrogen-bonded 1,3,5-triazine-water complexes

The 1,3,5-triazine-water hydrogen bonding interactions have been investigated using the density functional theory B3LYP method and 6-31 + + G** basis, obtaining one, two and seven energy minima of the ground states for the 1,3,5-triazine-water, 1,3,5-triazine-(water)2 and 1,3,5-triazine-(water)3 complexes respectively. The fully optimized geometries and binding energies were reported for the various stationary points. The global minima of 1,3,5-triazine-(water)(2) and 1,3,5-triazine-(water)(3) complexes have a hydrogen bond N center dot center dot center dot H--O and a chain of water molecules, terminated by a hydrogen bond O center dot center dot center dot H-C. The binding energies are 13.38, 39.52 and 67.79 kJ/mol for the most stable 1,3,5-triazine-water, 1,3,5-triazine-(water)2 and 1,3,5-triazine-(water)3 complexes respectively, after the basis set superposition error and zero point energy corrections. The H-O symmetric stretching modes of water in the complexes are red-shifted relative to those of the monomer water. In addition, the NBO analysis indicates that inter-molecule charge transfer is 0.02145 e, 0.02501 e and 0.02777 e for the most stable 1 : 1, 1 : 2 and 1 : 3 complexes between 1,3,5-triazine and water, respectively.