Development of amoxicillin-Fe(III) complex material for enhanced antimicrobial activities: in vitro antibacterial evaluations

Coordination with transition metals can increase the effectiveness of antibiotics against bacteria. In this context, the paper aimed to synthesise the complex of Fe (III) (ferric) with amoxicillin as a ligand in aqueous solution along with characterizing the molecular structure using spectroscopic studies, Fourier Transform infra-red (FT-IR) spectroscopy, dynamic light scattering (DLS), thermogravimetric analysis (TG), elemental (CHNS) analysis, powder x-ray diffraction (PXRD), scanning electron microscope (SEM), and energy dispersive x-ray (EDX). Further, the antibacterial activity of the amoxicillin-iron Fe(III) complex was elucidated. The strong band at 3400 cm−1 in the pure amoxicillin, which shifted to 3300 cm−1 in the complexes, is assigned to υ (OH) stretching frequency. The band of υ NH (amide) was obtained at 2950 cm−1, and the band of υ C=O (lactam) appeared at 1770 cm−1. The υ (–COO) mode was absorbed as a characteristic peak in the region of 1500 cm−1 in free amoxicillin, which was shifted to the region of 1450 cm−1 in the complex. The PXRD shows that the metal complex of amoxicillin has a crystalline size of 613.03 nm. The refractive peaks of the amoxicillin- Fe complex are obtained at 12.2°, 15.1°, 18.4°, 19.3°, 23.8°, 25.9°, 28.6°, and 28.8°. Further, the obtained amoxicillin complex of Fe(III) was evaluated for its biological activity on some bacterial species, which include Alcaligenes sp. MMA, Burkholderia sp. WA, and Stenotrophomonas sp. WA5. No bacterial growth was observed in the complex, which shows that the complex has bactericidal activity against the bacteria, as it is a newer antimicrobial agent for the bacteria, and bacteria have not yet developed resistance. Bacterial growth was observed in the case of amoxicillin, showing the bacteria’s resistance to the antibiotic.