Synthesis, structural characterization, Hirshfeld surface analysis and third-order nonlinear optical properties of Schiff bases derived from 1,1-diphenylmethylamine

Abstract

Two Schiff bases namely, (E)-4-((benzhydrylimino) methyl)-N,N-dimethylaniline (I) and (E)-N-(4-isopropylbenzylidene)-1,1-diphenyl methanamine (II) were synthesized by one pot condensation reaction. The structures were confirmed by single-crystal X-ray diffraction (SXRD) analysis. The molecules are associated by C‒H···π and π···π interactions which are responsible for the formation of supramolecular network. The compounds are further characterized by FT-IR, 1H and 13C NMR spectral analysis. The UV–Vis-NIR and photoluminescence spectral data of the compounds were studied to explore the optical transmission and emission properties respectively. The surface morphological changes in the compounds were observed by scanning electron microscopic (SEM) analysis. TG-DTA methods were used to point out the thermal stability of the compounds. The third-order nonlinear optical property was investigated in detail using Z-scan technique. The optimized geometry, molecular electrostatic potential (MEP) maps, Mulliken atomic charge distribution and first-order molecular hyperpolarizability were calculated using density functional theory (DFT) calculations using the B3LYP method with 6–311 G as basis set. Intermolecular interactions were studied using 3D Hirshfeld surface maps and the percentage contributions of various interactions are studied and quantified by 2D fingerprint plots.