Iron(III) and copper(II) complexes bearing 8-quinolinol with amino-acids mixed ligands: Synthesis, characterization and antibacterial investigation

Abstract

Four d-orbital metal complexes with mixed ligands derived from 8-hydroxyquinoline (HQ) and amino acids (AA): l-alanine and methionine have been synthesized through a mild reflux in alkaline solution and characterized by elemental analyses, infrared, electronic transition, and temperature dependant magnetic susceptibility. The IR spectroscopy revealed that iron and copper ions coordinated through carbonyl (CO), hydroxyl group (OH) of the amino acids, N-pyridine ring of hydroxyquinoline. The elemental analysis measurement with other obtained data suggested an octahedral geometry for the iron(III) complexes and tetrahedral geometry for the copper(II) complexes. From the molar magnetic susceptibility measurement, the iron(III) system (S = 5/2) d5 (non-degenerate 6A1) with χmT = 0.38 cm3 Kmol−1 showed an antiferromagnetic while Cu2+ ions system (S = ½) (2T2g) has χmT = 4.77 cm3 Kmol−1 described as paramagnetic behaviour. In vitro antimicrobial investigations of the metal complexes against standard bacteria species gave significant inhibition with, copper complex showing highest inhibitions against Pseudomonas aeruginosa (ATCC27853) of 43 mm at 10 μg/ml signalling its potential as pharmaceutical or chemotherapeutic agents.

Keywords

• Metal complexes
• Mixed ligands
• Magnetic susceptibility
• Antibacterial activity