Abstract:

β-cyclodextrin (β-CD) induced aggregation and micelle formation of cetyltrimethylammnium bromide (CTMAB) in aqueous solution is demonstrated by the dual fluorescence of p-N, N-dimethylaminobenzoic acid (DMABOA) typical of the twisted intramolecular charge transfer (TICT). The locally excited (LE) state of DMABOA is proved to have the characteristic of intramolecular charge transfer (ICT) with a polarity higher than that of ground state but lower than that of TICT state. The peak positions of the two fluorescence bands and their intensity ratio are employed to probe the interaction of β-CD with CTMAB. It is conc1uded that β-CD induces CTMAB aggregation as well as micelle formation and may change micelle structure. The results also indicate that TICT in aqueous solution may be affected by the anisotropy or viscosity of the medium, increasing viscosity disadvantaging the TICT process.

Key words: Micelle formation, Cyclodextrin inducement, Fluorescent probe, Twisted intramolecular charge transfer