Synthesis of indole borate ligand with Ni(II) and Cu(II) complexes

A new borate derivative (2,2',2'',2'''-((ʎ4-boranetetrayl)tetrakis(1H-indole-1,3-diyl))tetraacetic acid)(BIN) was synthesized from the reaction of indole-3-acetic acid (IAA) with sodium tetrahydroborate NaBH4 at a 4:1 mole ratio. This ligand was characterized by 1HNMR, FTIR, electronic spectra (UV-Vis.) thermal analysis (TG and DTG), elemental analysis (CHN) and melting point. Nickel and copper complexes were also synthesized and characterized by CHN, UV-Vis, atomic absorption, FTIR, melting point, magnetic susceptibility and molar conductivity. Results of analyses were in agreement with suggested structures. The results showed that the structure of nickel complex was octahedral while the copper complex was square planar and both complexes were nonelectrolytes. Antimicrobial activity against four kinds of bacteria Staphylococcus aureus and Streptococcus (G+), E. coli and Pseudomonas aeruginosa (G‒) as well as one fungus Candida albican exhibited that the copper complex has higher antimicrobial activity. Total antioxidant results showed that the BIN ligand has higher activity at 50 and 100 μg/mL while the copper complex has more antioxidant activity at 150 μg/mL. Bull. Chem. Soc. Ethiop. 2025, 39(4), 703-712. DOI: https://dx.doi.org/10.4314/bcse.v39i4.8