Molecular and Electronic Structure on n-Alkyl Cyanobiphenyl Nematogens

Abstract

First principle electronic structure calculations ( ab initio and density functional) were performed on a series of substituted cyanobiphenyls to examine the structural and electronic properties as a function of the alkyl tail length and changes in torison angle about the central bond connecting the rings. We find good agreement between our results and previous electronic structure studies for the optimized torsion angle between phenyls in the cyanobiphenyls, and changes in dipole moment for the cyanobiphenyls. We also find the torsion angle and rotational barriers in cyanobiphenyls to be similar to that in simple biphenyl. However, we find large discrepancies with the recent density functional calculations, which reported a much smaller torsion angle in the cyanobiphenyls.