Investigation on the growth, structural, vibrational, SHG behaviour and DFT studies of imidazolium hydrogen succinate single crystal.

Good quality NLO single crystal of imidazolium hydrogen succinate was grown by slow evaporation solution method with deionized water as the solvent. The grown crystal was subjected to various analytical measurements. Crystalline phase and structural parameters were investigated from the X-ray diffraction pattern. Optical transparency of 63% with UV cut-off wavelength at 234 nm and band gap (E_g) of 5.2 eV were measured from UV–Vis–NIR spectra. The thermal parameters were measured from TG–DTA. SHG efficiency was measured by Kurtz and Perry powder technique. Density functional theory (DFT) calculations have been investigated by the DFT/B3LYP/6-311G (d, p) method. HOMO–LUMO energy gap value was calculated to be around 5.12 eV, and ionization potential (I), electron affinity (A) and related properties were evaluated. Intermolecular hydrogen bond networks and fingerprint plots were analysed and generated by Hirshfeld surface analysis. Natural bond orbital analysis was found to give a π-delocalization effect with molecular correlation due to charge transfer from the donor–acceptor orbital. The dipole moment, polarizability and first-order polarizability value were calculated. Furthermore, the analysis of the Mulliken atomic charge was performed to understand the charge of the atoms. [ABSTRACT FROM AUTHOR]