New acyclic Schiff-base copper(II) complexes and their electrochemical, catalytic, and antimicrobial studies

Abstract

A new series of acyclic mononuclear copper(II) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and copper perchlorate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show a d–d transition in the range 500–800 nm, electrochemical studies of the complexes show irreversible one-electron-reduction process around −1.10 to −1.60 V. The reduction potential of the mononuclear copper(II) complexes shifts toward anodic direction upon increasing the chain length of the imine compartment. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μ _eff = 1.72–1.76 BM, close to the spin-only value of 1.73 BM. Electrochemical and catalytic studies of the complexes were compared on the basis of increasing the chain length of the imine compartment. All the complexes were screened for antifungal and antibacterial activities.

Keywords:

• Schiff-base ligands
• Copper(II) complexes
• Cyclic voltammetry
• Catecholase activity
• Antimicrobial activity

Acknowledgments

Financial support from CSIR, New Delhi is gratefully acknowledged.