Conformational Changes in Structure of 4-Methoxybenzylidene-4'-n-Butylaniline at Temperatures Corresponding to Different Phases and Phase Transitions

Abstract
The conformational behavior of 4-methoxy-benzilidene-4'-n-butylaniline at temperatures corresponding to different phases and phase transitions has been studied by quantum chemistry methods. It was shown that «non-rigidity» of the MBBA molecule is provided by a low mobility of the benzene rings and the butyl group. A comparison of the obtained results with the molecular dynamics simulation data for MBBA is performed. According to quantum-chemical modeling and taking into account the isolated molecule’s approximation the conju-gation of p-electrons of the oxygen atom with the π-electron cloud of the benzene ring leads to the planar position of the methoxy-group. At the same time, the influence of the surround-ing molecules in the bulk phase leads to a rotation of CH₃O-group in the plane which is perpendicular to the plane of the benzene ring.

Keywords: structure, conformation, liquid crystals