Unexpected fluorescence enhancement of naphthylethyl lauryl ether in coaggregation with variant aggregators.

Unexpected fluorescence enhancement has been observed during the coaggregation process between naphthylethyl lauryl ether (the fluorescence probe) and vitamin E acetate in aqueous organic binary solutions. Variant aggregators were used to study the influence of structure features on the enhancement. The experiments indicate that a long hydrophobic hydrocarbon chain is of necessity for coaggregation, and a flat group is crucial for the fluorescence enhancement. No enhancement was observed at the absence of coaggregation. The enhancement was attributed to the hindrance of rotations and prolonged life time of the probe by steric hindrance of flat groups in coaggregate. Structure features of aggregates of variant aggregators have also been discussed.