EXCIPLEX FORMATION BETWEEN PYRENE DERIVATIVES AND N,N-DIMETHYLANILINE IN AEROSOL-OT REVERSED MICELLES

The fluorescence spectra, fluorescence decay times, and the fluorescence quantum yield of the exciplexes formed between several fluorescent probes containing the pyrene chromophore with dimethylaniline were studied in reversed micellar solutions made from sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and water in n-heptane. The pyrene probes used were 1-methylpyrene (1-MP), (1-pyrenylmethyl)-trimethylammonium iodide (PMTMA), (4-(1-pyrenyl)butyl)trimethylammonium bromide (PBTMA), and (11-(1-pyrenyl)undecyl)trimethylammonium iodide (PUTMA). For the detergent-like probes, which are bound to the micellar interface, the fluorescent properties are dependent on the length of the aliphatic chain of the probe and the water to AOT ratio in the reversed micelles (R). The fluorescence emission maxima shift to the red and the fluorescence quantum yields and fluorescence decay times decrease with the water content of the micelle. For probes like 1-MP which are not bound to the interface, the emission maxima shift to the blue with an increase in R. The PBTMA-DMA exciplex was also studied in n-decane solutions.