Optical absorption behavior and spectral shifts of fluorinated liquid crystals in ultraviolet region: A comparative study based on DFT and semiempirical approaches

Abstract

Fluorinated liquid crystals p-phenylene-4-methoxybenzoate-4-trifluoromethylbenzoate (FLUORO1), and 4-propyloxyphenyl-4-(4-trifluoromethyl benzoyloxy) benzoate (FLUORO2) have been optimized by the density functional B3LYP with 6-31+G(d) basis set using crystallographic geometry as input. Using the optimized geometry, electronic structures of the molecules have been evaluated using the density functional theory (DFT), and semiempirical calculations. Molecular charge distribution, and phase stability of these systems have been analyzed based on Mulliken, and Loewdin population analysis. The absorption spectra of the molecules have been simulated by employing DFT method, semiempirical CNDO/S+CI, and INDO/S+CI parameterizations. The optical absorption behavior and the spectral shifts of these systems have been analyzed with respect to the changes in molecular structure, and the employed parameterizations. The effects of substituted groups on transition energies, HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), its gap, and absorption spectral shifts have been discussed. An attempt has been made to understand the application, and operation of the molecules in ultraviolet and visible light regions.