Synthesis, crystal structure, Hirshfeld surface analysis and DNA binding studies of 1-((E)-3-(4-bromophenyl)-1-phenylallylidene)-2-(m-tolyl)hydrazine

Abstract

1-((E)-3-(4-bromophenyl) -1-phenylallylidene)-2-(m-tolyl)hydrazine (4) was synthesized and characterized for structural elucidation by spectroscopy (FT-IR, 1H NMR, and 13C NMR) and single crystal X-ray diffraction. In the title compound, the benzene rings A, B, C were oriented at dihedral angles {A/B = 82.92 (3)°, A/C = 24.12 (3)°and B/C = 75.90 (3)°}. Crystal structure showed that intermolecular CH⋯O and CH⋯N hydrogen bonds linked the molecules, enclosing R22 (10) and R22 (16) ring motifs. The Hirshfeld surface analysis of the crystal structure indicated that the most important contributions for the crystal packing were from H⋯H (46.0%), H⋯C/C⋯H (17.6%), H⋯Br/Br⋯H (12.4%), H⋯O/O⋯H (8.5%) and C⋯C (6.6%) interactions. Hydrogen bonding and van der Waals contacts were the dominant interactions in the crystal packing. Compound's interaction with DNA was further investigated theoretically by DFT and experimentally by UV–visible spectroscopy and cyclic voltammetry. DFT analysis in terms of geometry optimization and computed parameters revealed reactive nature of 4 and the possibility of planar phenyl rings to intercalate within the DNA base pairs. Spectral and voltammetric analysis and related binding parameters suggested intercalation as a possible mode for 4 – DNA binding which was further verified by viscosity measurements.