Theoretical (DFT) and experimental studies on multiple hydrogen bonded liquid crystals comprising between aliphatic and aromatic acids

摘要

AbstractLiquid crystalline complex has been designed from non-mesogenic citric acid (CA) and mesogenic 4-undecyloxybenzoic acid (11OBA) in different mole ratio by means of intermolecular hydrogen bond. Optimized geometry for CA+11OBA (1:1) HBLC complex using density functional theory (DFT) at B3LYP level with 6-311G (d, p) basis set has been studied. Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), hydrogen bond length/angle, electrostatic potential (ESP) and Mulliken charge distribution for the HBLC complexes are theoretically determined. Further atomic, molecular properties and charge transfer capability of present HBLC complex is evaluated from HOMO/LUMO energies. Theoretically calculated vibration frequencies of HBLC complex is validated through experimentally recorded Fourier transform infrared (FT-IR) spectrum. Characteristic features of various textures by polarizing optical microscopy (POM) and temperature dependent of various thermodynamic properties of CA+11OBA complexes are carefully investigated. Enantiotropic nematogen and finger print smectic X textures along with their phase sequences are also analyzed. Structural and optical characteristics of present HBLC complexes are evinced by nuclear magnetic resonance (1H NMR) and UV–Vis spectrophotometer (for band gap) techniques. The impact of mesogenic ratio (11OBA) on CA+11OBA complex is also discussed. In this present work, a noteworthy observation of photocatalytic activity of CA+11OBA HBLC complex is noticed. Also, textural changes with phase transition temperature, induced smectic phases, thermal range, enthalpy, and tilt angle are reported. Presenc