Spectroscopic, crystal structural, theoretical and biological studies of phenylacetohydrazide Schiff base derivatives and their copper complexes

Abstract

Two phenylacetohydrazide Schiff base derivatives: N’-(1-(2-hydroxyphenyl)ethylidene)-2-phenylacetohydrazide, HL1, and N’-((1-hydroxynaphthalen-2-yl)methylene)-2-phenylacetohydrazide, HL2, were synthesized. HL1 dimerizes in presence of HCl, probably via radical mechanism to give (2,2’-((1E)-hydrazine-1,2-diylidenebis(ethan-1-yl-1-ylidene))diphenol (DIM). Thermal reactions of Cu(II) ions with the two Schiff base ligands resulted in formation of the binuclear complexes [(CuL1)2] and [(CuL2)2]. The stoichiometry and structures of the reported compounds were investigated by several spectroscopic and analytical techniques. The structure of the HL1 ligand and its complex [(CuL1)2] as well as the DIM derivative were analyzed by single crystal X-ray analysis. The X-ray analysis revealed the binuclear coordination of the copper complex with the formation of five- and six-membered rings with every ligand. The molecular geometries of the ligands and their copper complexes were investigated using the DFT‐B3LYP/GENECP level of theory. The optimized structures of the studied complexes are consistent with the finding of the X-ray analysis. The quantum, non-quantum global reactivity descriptors and the non-linear optical properties were calculated. Biological studies including, antimicrobial and antioxidant activities of the complexes along with fluorescence quenching studies and viscosity measurements are carried out. The molecular docking of the two ligands and [(CuL2)2] complex is also reported. The different biological studies as well as molecular docking are correlated to each other and supported the fact that the complexes can bind to DNA via intercalative mode and showed a various DNA binding potency.