Synthesis, characterization, crystal structure, electrochemical, solvatochromic and biological investigation of novel N4 and N3 type Cu(ii) Schiff base complexes

Abstract

In the present study, three novel Cu(II) Schiff base complexes [CuL](ClO₄)₂, [CuL′Cl₂] and [CuL′(NO₃)₂] (L: N,N′-bis(2-pyridinylmethylene)-1,2-diphenylethylenediamine and L′: N-(2-pyridinylmethylene)-1,2-diphenylethylenediamine) were synthesized and characterized using infrared spectroscopy, elemental analysis, conductivity measurements and X-ray crystallography. The crystal structure of the [CuL′(NO₃)₂] and [CuL′Cl₂] complexes were determined by X-ray crystallography. However, suitable single crystals for [CuL](ClO₄)₂ could not be obtained. The complexes were assessed to determine their thermal, electrochemical and biological behaviors and electronic absorption. Among the complexes, only the [CuL](ClO₄)₂ complex showed solvatochromic properties in various solvents. The antibacterial activities of these complexes were evaluated in Muller-Hinton broth against Staphylococcus aureus, Escherichia coli and Enterococcus faecalis using the serial dilution technique at concentrations ranging from 2 to 0.0625 mg mL⁻¹. The data demonstrates that the complexes were bacteriostatic agents that inhibit bacterial growth, but had no bactericidal properties.