Structural, spectral and biological investigations on Cu(II) and Zn(II) complexes derived from NNO donor tridentate Schiff base: Crystal structure of a 1D Cu(II) coordination polymer

Abstract Copper(II) and zinc(II) complexes of an NNO donor tridentate Schiff base, 4-bromo-2-(((3-(methylamino)propyl)imino)methyl)phenol (HL), were synthesised and characterized by different physicochemical methods including single crystal XRD, elemental analysis, IR, electronic and EPR spectral analysis. Copper(II) complex is a 1D coordination polymer in which chlorine acts as a bridging ligand and zinc(II) complex is a bis-ligated one. Hirshfeld surface analysis of the complexes has been carried out which provided better understanding of intermolecular interactions. Effects of solvents on charge transfer bands and d-d bands were investigated and the former shows a negative solvatochromic behaviour and latter a positive behaviour upon increasing solvent polarity. Luminescent properties were analysed and found that copper(II) and zinc(II) complexes exhibit quenching and enhancement of fluorescence respectively which is backed by quantum yield values. Cytotoxic activity of both complexes has been screened in vitro against lymphoma ascites cell lines. In addition, antibacterial activity of complexes has been screened against bacterial species Bacillus cereus, Staphylococcus aureus, Klebsiella pneumonia and Escherichia coli.