A Comparitive Study of Antimicrobial Screening of Copper and Nickel Salophen Complexes

• Dr.R.Jeevi Esther Rathnakumari

  english

  Author

The emergence of multidrug-resistant microorganisms has created an urgent demand for the development of novel antimicrobial agents with enhanced biological efficacy. In the present investigation, Copper and Nickel salophen complexes derived from the Schiff base ligand N,Nʹ-bis(salicylidene)-1,2-phenylenediamine were synthesized, characterized, and evaluated for their antimicrobial potential against selected pathogenic microorganisms. The salophen ligand was synthesized through the condensation of salicylaldehyde and 1,2-phenylenediamine in ethanolic medium, followed by complexation with Copper(II) sulfate and Nickel(II) sulfate to obtain the corresponding metal complexes.  Structural characterization of the synthesized ligand and complexes was carried out using FT-IR and ESI-mass spectral analyses. FT-IR spectral data revealed characteristic azomethine ν(C=N) stretching vibrations in the range of 1601–1620 cm⁻¹, confirming Schiff base formation and coordination of azomethine nitrogen atoms with the metal ions. ESI-mass spectra further confirmed the molecular masses of the synthesized Copper and Nickel salophen complexes.  The antimicrobial activity of the complexes was evaluated by agar well diffusion method against Gram-positive bacteria (Staphylococcus spp. and Enterococcus spp.), Gram-negative bacteria (Klebsiella spp. and Escherichia coli), and fungal species (Aspergillus spp.). The Copper salophen complex demonstrated moderate antibacterial activity against Enterococcus spp. with a zone of inhibition of 15 mm, whereas the salophen ligand exhibited 12 mm inhibition. Nickel salophen complex did not show significant antibacterial activity against the tested microorganisms. Antifungal studies revealed slight inhibitory activity of Copper salophen complex against Aspergillus spp. with a 4 mm zone of inhibition.

The enhanced biological activity of the Copper complex was attributed to chelation effects, increased lipophilicity, and improved penetration through microbial cell membranes according to Overtones concept and Tweedy’s chelation theory. The study concludes that Copper salophen complexes possess promising antimicrobial potential and may serve as effective candidates for the development of future metal-based therapeutic agents against resistant microbial pathogens.

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