Photophysical properties of levofloxacin and norfloxacin drugs and their fluorescence quenching mechanism with caffeine

Abstract

Levofloxacin and norfloxacin are drugs used to treat various infections originating from bacterial species. In this research, the photophysical properties of the drugs were investigated using ultraviolet–visible absorption and fluorescence spectroscopic techniques. The results indicated the fluorescence quantum yields, lifetime, and non-radiative decay of the drugs are affected by solvent polarity and drug concentration. The binding mechanism of levofloxacin–caffeine and norfloxacin–caffeine were determined using the fluorescence quenching method. The quenching of drugs induced by caffeine is due to ground state complexes. The binding occurs spontaneously due to electrostatics, hydrogen and Van der Waals force play a major role in the reaction.