[Study on the interactions between a 3H-indole probe molecule and Triton X-100 micelles by spectral methods]

The interactions between a fluorescent molecule, [2-(p-hexylamino) phenyl-3,3-dimethyl-5-ethoxycarbonyl-3H-indole] methyldiioctadecylammonium iodide (A), with Triton X-100 micelle are investigated by absorption and fluorescence spectra. The relatively large binding constant Ks shows that strong interactions between A and micelles do exist. The polarity parameter confirms that the polarity of the environment of A in the micelle is similar to that of methanol. According to the spectral characteristics and pH effects, the various sites of different groups of A in micelles are suggested. Lifetime measurements indicate that A can recognize two sites with Triton X-100 micelle at lower surfactant concentration. However, in the Triton X-100 micelle at higher surfactant concentration, A can only recognize one site.