PHOTOCHEMISTRY IN MICROEMULSIONS - FLUORESCENCE QUENCHING OF 1-NAPHTHOL AND 2-NAPHTHOL BY CU2+

The fluorescence characteristics of 1- and 2-naphthol in the presence of copper ion have been studied in aqueous medium and sodium lauryl su lphate (NaLS)-isobutanol-hexane-water microemulsion. On excitation 1-n aphthol (1-ROH) dissociates completely and 2-naphthol (2-ROH) partiall y in aqueous medium. The dissociation of 2-ROH is suppressed completel y and that of 1-ROH partially in the microemulsion. The extent of diss ociation of 1-ROH varies with changing microemulsion formulation. The dissociation behaviour and fluorescence quenching of naphthols by Cu2 in the microemulsion suggest a compartmentalization of the fluorophor es. Various quenching models have been analysed to explain the quenchi ng efficiency. A generalized model explaining both the dynamic and tra nsient quenching processes has been proposed. The probable number of q uenchers present in the quenching sphere of action has been calculated .