Abstract: The absorption behaviour of carborane diester liquid crystals viz., bis(4-propyloxyphenyl) 1,12-dicarba-closo-dodecaborane-1,12-dicarboxylate (C22H32B10O6), and bis(4-butoxyphenyl) 1,10-dicarba-closo-decaborane-1,10-dicarboxylate (C24H34B8O6) have been studied in ultraviolet (UV), and visible (Vis) regions. Structure of these nematogenic molecules have been optimized using the Density functional B3LYP with 6-31+G (d) basis set using crystallographic geometry as input. Molecular charge distribution and phase stability of these systems have been analyzed based on Mulliken and Loewdin population analysis. The electronic absorption spectra of the molecules have been simulated by employing the DFT method, semiempirical CNDO/S and INDO/S parameterizations. The UV absorption behaviour and stability of the molecules has been discussed based on the absorption spectra data, and group charge distributions.

Keywords: Liquid crystal; UV-Visible spectra; Oscillator strength; Phase stability.