Enhancing antimicrobial efficacy: 8-Hydroxyquinoline incorporation into metal-organic frameworks with iron ion coupling

The antimicrobial properties of 8-Hydroxyquinoline (8-Hq), a small organic compound known for its metal-chelating capabilities, hold significant promise. However, its limited solubility in water poses a challenge for practical applications. In this study, we address this limitation by augmenting the antimicrobial efficacy of 8-Hq through its integration into the metal-organic framework UiO-66 (named 8-Hq@UiO-66) and coupling it with iron ions (designated as Fe/8-Hq@UiO-66) via an adsorption process. The sorption isotherm and adsorption kinetics were meticulously examined using Langmuir's adsorption model and the pseudo-second-order kinetic model. Material characterization techniques including powder X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption isotherms, ultraviolet–visible spectroscopy, and photoluminescence spectroscopy revealed the coordination of zirconium clusters and iron with the nitrogen and hydroxyl groups of 8-Hq, respectively. Furthermore, our investigation into metal ion adsorption demonstrated that the 8-Hq@UiO-66 composite displayed a notable selectivity for iron ions over other metal ions in aqueous media. Under optimized conditions, the adsorption capacity for iron ions ranged from approximately 34–46 mg g–1. Importantly, the Fe/8-Hq@UiO-66 composite exhibited potent antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. These findings underscore the potential of incorporating 8-Hq into porous metal-organic frameworks and coupling it with iron ions to enhance its antimicrobial efficacy.