Electronic and structure conformational analysis (HOMO-LUMO, MEP, NBO, ELF, LOL, AIM) of hydrogen bond binary liquid crystal mixture: DFT/TD-DFT approach

Abstract

Novel hydrogen bond liquid crystal (HBLC) binary mixture is designed and optimized through density functional theory (DFT) calculation and time dependent density functional theory (TD-DFT). HBLC binary mixture is derived from mesogenic compounds of liquid crystalline 4-methoxycinnamic acid (4MCA) and 4-hexyloxybenzoic acid (6OBA). Theoretically predicted vibrational IR assignments HBLC binary mixture is compared with experimental FTIR and validated. TD-DFT calculation is used to identify electronic absorption spectrum of HBLC binary mixture. Molecular electrostatic potential analysis explores the electrophilic/nucleophilic charge distribution and chemical reactivity of binary mixture, whereas natural bond orbital (NBO) study discloses the possible intermolecular hyper-conjugative interaction. HOMO and LUMO study shows charge transfer phenomena between 4MCA and 6OBA compounds. Further, Topological studies confirm the strong hydrogen bond between 4MCA and 6OBA. It is identified as the π- π stacking of the aromatic part of carboxylic acid plays an important role in the improved phase stability of mesophases.