Fluorescence quenching of naphthols by Cu2+ in micelles

Abstract

Effect of the micelles of anionic, cationic and non-ionic surfactants on the fluorescence quenching of 1- and 2-naphthols has been studied in the presence of copper ion. The excited state lifetime, dynamic and static quenching constants for these systems have been determined. Fluorescence quenching in water and SDS micelle is due to the collision of the fluorophore with the quencher with a small static component. The negatively charged naphtholate ions in the excited state are quenched with significantly higher rates than the neutral naphthol molecules, which are located further inside the mesophase. CTAB micelle is less effective than the SDS micelle for fluorescence quenching. The effect of CTAB on water-assisted excited-state deprotonation has been investigated in the presence of ZnSO4. For TX-100 micelle there is negligible quenching even at higher concentration of the quencher.

Keywords

• Naphthol
• Fluorescence
• Micelle
• Dynamic quenching
• Static quenching
• Excited state lifetime