QUANTUM CHEMICAL STUDIES OF ORGANIC LIQUID CRYSTAL AS SEMICONDUCTOR-FROM QUANTUM MECHANICS TO FLEXIBLE MATERIALS

Abstract

Now a days, the low cost energy sources are vital to investigate the energy crises and demand of energy for high productivity. Current study involves three Parent discotic liquid crystal compounds namely (1) Benzene-1,3,5-triyl tris(3,5-dialkoxybenzoate), (2) N1, N3, N5-tris(3-alkoxyphenyl)benzene-1,3,5-tricarboxamide, (3) Trialkyl 4, 4’, 4”-(benzenetricarbonyltris (azanediyl)) tribenzoate benzoate and their N, S containing derivatives have been optimized using Quantum chemical DFT studies at B3LYP level of theory together with LanL2DZ basis set whereas charge transfer integrals were calculated employing Single Zeta basis set (SZ) along with GGA(PW91) functional to investigate electron and hole mobilities of DLCs, highest probability of charge transfer was found to be 0.76×102 eV for -NH-CO-CH3 derivative of (1). Lowest dersiable value of HOMO-LUMO gap was achieved as 3.19eV for -NH-CH3 and -S-CH3 containing derivative of (1) leading to the highest value of electrical conductivity 0.8832Sm-1. Thermodynamic parameters and stability of compounds were determined through frequency calculations to examine the better understanding of the thermochemistry and effect of substituents on vibrational frequency analysis of discotic liquid crystal, derivative of (1) having R= -NH-CO-CH3 terminal group came out to be theoretically favored than all other derivatives. UV/Vis spectroscopic analysis was carried out to determine excitation energy, amount of absorbance and hence transmittance of DLCs and their derivatives. Maximum excitation energy 261.98nm was obseved by replacing -NH-CO-CH3 with –CH3 group of derivative of (1). However, lowest absorbance and maximum transmittance was figure out to be 0.60 in -S-CH3 substituted structure of (2). Electrophilic and nucleophilic characteristics of DLCs were monitored by molecular electrostatic potential map at certain potential range i.e., -8.531e-3 esu to +8.531e-3esu. The effect of substituents on parent DLCs was explored to reduce the HOMO-LUMO gap, enhance stability, excitation energy, charge transfer integral and optoelectronic properties of DLCs.