COMPLEXATION OF AL(III) BY 8-HYDROXYQUINOLINE AND DRASTIC FLUORESCENCE ENHANCEMENT IN REVERSE MICELLES

Complexation of Al-III by 8-hydroxyquinoline and fluorescence behavior of the quinolinate(s) were studied in reverse micellar systems at low water content, and compared to aqueous media. Two surfactants were us ed: one was cationic (CTAC: cetyltrimethylammonium chloride) and the o ther was anionic (AOT: sodium bis(2-ethylhexyl)sulfosuccinate). The re sults obtained in the CTAC/dichloromethane system (W = [H2O]/[surfacta nt] = 0.9) showed that complexation occurred very likely in the oil ph ase and no micellar effect was observed. On the contrary, in the prese nce of AOT, specific micellar effects were observed due to the presenc e of the anionic polar heads: stabilization of the positively charged 1:1 and 1:2 chelates, at the expense of the neutral water-insoluble 1: 3 chelate which is formed in aqueous solutions under similar condition s; drastic fluorescence enhancement factors of 120 and 100 in AOT/hept ane (W = 1.5) and AOT/dichloromethane (W = 1.6), respectively. Such fa ctors have never been reported so far in either hydroorganic or direct micellar systems. In return, the length of time for the production of the complex(es) is increased because of the microheterogeneity of the medium and the small sizes of the water pools. (C) 1998 Academic Pres s.