DFT conformational study of five-ring bent-core mesogens with a central 1,3‐phenylene unit

Muthanna Journal of Pure Sciences – MJPS

Vol.3 – No. 2 / October 2016

Shatha Raheem Helal Alhimidia, Muhsen Abood Muhsen Al-Ibadib and
Abbas H. Abo Nasriaa
a Department of Physics, College of Science, University of Kufa
b Department of Chemistry, College of Science, University of Kufa

Abstract

The potential energy surfaces of the five-ring bent-core molecules with a central 1,3-phenylene unit, including azobenzene with alkyloxy as terminal chains, has been investigated by using density functional theory (DFT). The PBE1PBE/6-31G(d,p) level of theory has been used for some computations in addition to the BP86 function, where used to study the influence of rotation of the connection groups. These computations were performed on the conformational behavior of the connection groups, included ester linkage group, N=N group and terminal OR group, of the five-ring bent-core compound in a systematic way. The relaxed rotation barrier with respect to the six torsion angles (φ1, φ2, φ3, φ4, φ5 and φ6) were calculated. It is interesting to note that the oxygen atoms of the linkage group, which are directly connected to the rings, give banana-shaped compounds with energy barrier by about 0.9 kcal mol-1 and high flexibility, whereas the ester group connected to phenyl ring by a carbon atom shows a high energy barrier by about 10.2 kcal mol-1 and a relatively limited conformational degree of freedom. The dependency of the Dipole moment on conformers with constraints to the torsion angle was studied.

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