Unraveled mesophase dynamics of discotic liquid crystal using combination of vibrational spectroscopy and DFT.

[Display omitted] • Optimized structure monomer and dimer structures of A10 DLC using DFT. • Microscopic molecular dynamics were revealed through FT-IR, FT-Raman, and DFT. • Predicted the mesomorphic models of nematic and columnar of A10. • QTAIM analysis predicts the strength and nature of hydrogen bonding. Utilizing temperature-dependent Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectroscopies, we delved into the spectral properties of 4-((2,3,4-tris(decyloxy)phenyl)diazenyl)benzoic acid, a fascinating discotic liquid crystal (DLC) named A10. Our investigation unravels valuable insights into conformational dynamics, intermolecular hydrogen bonding, and structural stability, throughout enantiotropic phase transitions (Isotropic (Iso) → Discotic Nematic (N D) → Columnar (Col) → Crystalline (Cry)) during cooling. To further understand the mesogen's phasmid structure at atomic level, density functional theory (DFT) is employed, utilizing the B3LYP/6-3116G(d,p) method for optimization and frequency calculations of monomer and dimer of A10. The alignment of computationally predicted molecular models with observed vibrational spectra at room temperature affirms the precision of our theoretical model. Innovatively, our study has uncovered the potential formation of dimer assemblies, demonstrating the persistence of intermolecular hydrogen bonding within these dimers throughout each phase transition of the DLC. Furthermore, we have identified the strength of both intermolecular and intramolecular hydrogen bonding. These findings expand our knowledge of this unique material and pave the way for further research in the field of liquid crystals. [ABSTRACT FROM AUTHOR]