A theoretical study of the intermolecular interactions in the p-azoxyanisole liquid crystal.

In the present work, we have analyzed the intermolecular interactions in a monomer and dimer of 4,4?-dimethoxyazoxybenzene (PAA) liquid crystal. These interactions were evaluated through the functionals PBE, PW91, M06-L, M06-HF, M06, M06-2X, B97-D and wB97X-D and different basis set. The results suggest that the wB97-XD/6-311++G(d,p), M06-2X/6-311++G(d,p) and M06L/6-311++G(d,p) levels of theory are adequate to analyze the intermolecular interactions of PAA dimers. The intermolecular interactions were analyzed through the non-covalent interaction index (NCI) and the LMO-EDA method. The results indicate that the electrostatic contribution to the total interaction energy in PAA dimers is above 85% suggesting that the alignment in this liquid crystal is caused mainly by the formation of intermolecular hydrogen bonds at the ends of PAA.