Synthesis, electrochemical, catalytic and antimicrobial activities of novel unsymmetrical macrocyclic dicompartmental binuclear nickel(II) complexes

Abstract

A series of novel unsymmetrical dicompartmental binuclear nickel(II) complexes have been prepared by simple Schiff base condensation of the compound 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane L with appropriate aliphatic or aromatic diamine, nickel(II) perchlorate and triethylamine. All the complexes were characterized by elemental and spectral analysis. Positive ion FAB mass spectra show the presence of dinickel core in the complexes. The electronic spectra of the complexes show the d–d transition in the range of 550–1040 nm. Electrochemical studies of the complexes show two irreversible one electron reduction process around E pc 1 = - 0.79 to − 1.27 V and E pc 2 = - 1.28 to − 1.43 V . The reduction potential of the binuclear nickel(II) complexes shifts towards anodically upon increasing chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible oxidation waves around 0.72 to +1.52 V. The observed rate constant values for catalysis of the hydrolysis of 4-nitrophenyl phosphate are in the range of 9.20 × 10 −3–16.81 × 10 −3 min −1. The rate constant values for the complexes containing aliphatic diimines are found to be higher than that of the complexes containing aromatic diimines. Spectral, electrochemical and catalytic studies of the complexes were compared on the basis of increasing chain length of the imine compartment. All the complexes were screened for antifungal and anti bacterial activity.