Evaluation of novel metal-Schiff base complexes as potent inhibitors against microbiologically influenced corrosion (MIC)

Abstract

Novel metallic complexes derived from a three coordinate hydrazine Schiff base ligand featuring an NNO electron donor system were prepared and characterized using FTIR, UV-Vis, ESI-MS, ¹H, ¹³C-NMR, and CHN elemental analysis, supported by magnetic susceptibility and molar conductivity measurements. Structural studies confirmed a 2:1 molar ratio (L:M) for Mn⁺², Co⁺², Ni⁺², Cu⁺², and Zn⁺² complexes, while Zr⁺⁴ exhibited a binuclear structure. Spectroscopic analysis revealed the ligand exists primarily in its enolic form. Based on the principle of structural similarity, an octahedral geometry was proposed for the divalent metal compounds and definitively confirmed for Cu⁺² via single-crystal X-ray diffraction (SC-XRD). To address microbial corrosion (MIC) challenges, the biological activity of these compounds (10^-3M) was evaluated as biocides against sulfate reducing bacteria (SRBs), fungal species (Botrytis aclada and Absidia corymbifera), and common pathogens. These included Gram positive bacteria (Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis) and Gram negative bacteria (Pseudomonas aeruginosa). Notably, the Schiff base and its complexes exhibited significant antimicrobial activity, demonstrating performance comparable to synthetic chlorine based biopesticides.

KEY WORDS: Schiff base, Hydrazones, Microbiological corrosion, Bacillus, Bortryis acaladia, Absidiomycete corimpifira

Bull. Chem. Soc. Ethiop. 2026, 40(10), 2221-2235.                                                  

DOI: https://dx.doi.org/10.4314/bcse.v40i10.12