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

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-hexyloxyben-zoic 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 distri-bution 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 phe-nomena between 4MCA and 6OBA compounds. Further, Topological studies confirm the strong hydrogen bond between 4MCA and 6OBA. It is identified as the 7C-7C stacking of the aromatic part of carboxylic acid plays an important role in the improved phase stability of mesophases.