Quenching of two conformers of the naphthalene derivative, nabumetone, in water

The quenching of the anti-inflammatory drug nabumetone by iodide was studied by means of steady-state and time-resolved fluorescence techniques. A downward curvature in the Stern–Volmer plot was observed. This behaviour has been interpreted based on the existence of two conformers of the drug that interact with the quencher with different ability, plus the low quenching efficiency of the quencher for both conformers. A drug quencher ground state complex was observed to be formed through an electron transfer from the iodide to the naphthalene ring of the nabumetone.