DFT conformational study of banana-shaped mesogens

The conformational energy of the 1,3-phenylene bis[4-4-(methoxy) benzoyloxy] benzoate and 4-chloro-1,3-phenylene bis[4-4'(methoxy) benzoyloxy] benzoate molecules has been studied using the B3LYP density functional, with a double polarized basis set. These molecules can be seen as a model for the aromatic core of recently discovered banana-shaped mesogens. The relationship between the bent molecular shape and the conformations assumed by the phenyl ester dihedrals is studied together with the effect of substitutions on the central ring. In particular, the inclusion of a chlorine atom in the central ring results in an increase of the bending angle, consistently with recent experimental findings. A discussion of the chirality of some of the resulting energy minima conformations is also given. (c) 2005 Elsevier B.V.. All rights reserved.