Cu(II) Complexes of 4-[(1E)-N-{2-[(Z)-Benzylidene-amino]ethyl}ethanimidoyl]benzene-1,3-diol Schiff Base: Synthesis, Spectroscopic, In-Vitro Antioxidant, Antifungal and Antibacterial Studies

Ikechukwu Ejidike

doi:10.3390/molecules23071581

Abstract

The current study reports the synthesis of copper complexes of a tridentate Schiff base ligand. The compounds of the type [Cu(L)X]∙n(H2O) (where L = tridentate ONN Schiff base ligand, X = Cl−, Br−, SCN−, NO3−, CH3COO−), were characterized on the basis of elemental analyses, FT-IR, UV-vis, molar conductance, 1H-NMR, XRD and thermal analyses. The spectra revealed that the Schiff base ligand acts as a tridentate ligand through two azomethine nitrogen atoms and a phenolic oxygen atom. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature. TGA and DTA studies results gave insight into the dehydration, thermal stability, and thermal decomposition. Square-planar geometry has been assigned to the prepared complexes as indicated by the electronic spectral measurements. Cu(II) compounds showed antiradical potential against DPPH and ABTS radicals. The antimicrobial potential of the Schiff base ligand and its Cu(II) complexes were evaluated by the rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay against some selected bacteria strains: Staphylococcus aureus and Enterococcus faecalis (Gram +ve); Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram −ve), and fungi (Candida albicans and Cryptococcus neoformans). The compounds showed a broad spectrum of antibacterial and antifungal activities, with MIC values ranging from 48.83 to 3125 μg/mL.

Highlights

IntroductionTransition metals are associated with biological processes that are indispensable to life processes
Transition metals are associated with biological processes that are indispensable to life processes.they can coordinate with O- or N-terminals from proteins in a variety of models, and thereby, play a vital role in the conformation and utility of living macromolecules [1,2], and act as antimicrobial agents [3]
2-Hydroxy-1-(4-hydroxyphenyl)ethenone Schiff bases are of particular interest due to their wide range of biological activities, as shown by 4-[(1E)-N-(2-aminoethyl)ethanimidoyl]benzene-1,3-diol [9], and antioxidant and antibacterial activities exemplified by derivatives of 1-phenylbutan-1-one

Summary

Introduction

Transition metals are associated with biological processes that are indispensable to life processes They can coordinate with O- or N-terminals from proteins in a variety of models, and thereby, play a vital role in the conformation and utility of living macromolecules [1,2], and act as antimicrobial agents [3]. Schiff bases containing imino moieties (>C=N–) and their metal complexes have been widely reported to exhibit a variety of interesting biological activities such as antimicrobial, anti-inflammatory, antifungal, antitumor, anticancer activities, antiproliferative and analgesic effects [2,4,5,6,7]. Copper(II) complexes of the quinolin-4(3H)-one Schiff base ligand derived from the reaction of 3-amino-2-methyl-4(3H)-quinazolinone with different substituted aromatic aldehydes was reported [13] to act as avid binding and cleaving agent.

Methods

Results

Conclusion