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…H-O and a chain of water molecules, terminated by a hydrogen bond O…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.

Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water complexes. The results show that the ground state complexes have strong hydrogen bonding interaction with -20.99, -16.73 and -15.31 kJ/mol after basis set superposition error and zero-point vibration energy correction for pyridazine-water, pyrimidine-water and pyrazine-water, respectively, and large red-shift for the symmetric H-O stretching vibration frequencies due to the formation of N…H-O hydrogen bond in the diazine-water complexes. The NBO analysis indicates that intermolecular charge transfer are 0.0316, 0.0255 and 0.0265 e respectively. In addition, the first singlet (n,π*) vertical excitation energy of the monomer and the hydrogen bonding complexes between diazines and water was investigated by time-dependent density functional theory.

Density functional theory B3LYP method with 6-31++G** basis was used to optimize the geometries of the ground states for 1,2,3-triazine-(H2O)n (n=1,2,3) complexes. All calculations indicate that the 1,2,3-triazine-water complexes in the ground states have strong hydrogen-bonding interaction, and the complex having a N HO hydrogen bond and a chain of water molecules which is terminated by a O HC hydrogen bond is the most stable. The HO stretching modes of complexes are red-shifted relative to that of the monomer. In addition, the Natural bond orbit (NBO) analysis indicates that the intermolecular charge transfer between 1,2,3-triazine and water is 0.0222e, 0.0261e and 0.0273e for the most stable 1:1, 1:2 and 1:3 complexes, respectively. The first singlet (n, *) vertical excitation energy of the monomer 1,2,3-triazine and the hydrogen-bonding complexes of 1,2,3-triazine-(H2O)n were investigated by time-dependent density functional theory.

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The structure optimization and frequency calculation of hexaazatriphenylene, triphenylene and their derivatives were carried out at the level of B3LYP/6-31G**, and the most stable configurations were obtained. On the basis of the most stable geometries, the relationships of the total energy with rotation degrees between the dimers were studied, and the lowest energy point was obtained. Based on the semi-classical model of the charge transport, our results predict that hexaazatriphenylene molecules have the largest positive charge transport rate and the smallest negative charge transport rate. Introduction of SH, OH, OR and F groups make the positive charge transport to increase, and the negative charge transport to decrease. The length of alkoxy group has little effect on charge transport properties.