Synthesis, molecular geometry, Hirshfeld surface analysis, spectroscopic (NMR, UV–visible), DFT and TD-DFT calculations of an azoimidazole-based Schiff base.

The molecular structure of Schiff base ZIm was investigated using spectroscopic (NMR, UV–vis) techniques. Theoretical calculations of the mentioned compound have been carried out using density functional theory at the B3LYP/6-31G(d) level of theory. Geometrical parameters such as bond lengths (Å) and angles (°) obtained by DFT calculations show excellent agreement with X-ray analysis result. The Hirshfeld surface (HS) analysis shows the different percentage interactions: H/H (49.8%), H/C (28.7%), N/H (15.2%) and O/H (5.7%) interactions. The 1H and 13C NMR chemical shifts with respect to TMS were calculated using the gauge-independent atomic orbital (GIAO) method in CDCl3 and compared with the experimental data. The UV–Vis spectrum of ZIm was computed with the B3LYP and CAMB3LYP functionals and the 6-31G(d) basis set in different solvents such as CHCl3, CH3CN, MeOH and DMSO. The frontier molecular orbital's (FMO's) analysis and molecular electrostatic potential surface (MEP) were investigated using theoretical calculations. The theoretical results show good agreement with the experimental results. [ABSTRACT FROM AUTHOR]