Aggregation-induced emission of an aminated silole: A fluorescence probe for monitoring layer-by-layer self-assembling processes of polyelectrolytes

A new fluorescence technique for monitoring layer-by-layer self-assembling processes of polycations and polyanions is developed in this work. The fluorescent probe is a fluorogenic dye named 1,1-bis[p-(diettlylaminomethyl)phenyl]-2,3,4,5-tetraphenylsilole (A(2)HPS). Whereas fluorescence of a "normal" fluorophore is often quenched by aggregate formation, the protonated salt of A(2)HPS, i.e., [H(2)A(2)HPS](2+), emits strong light in the Suspensions of its nanoaggregates and in the solid films of its blends with poly(diallyldimethylammonium chloride) (PDDAC), thanks to its novel aggregation-induced emission (AIE) characteristics. When ([H(2)A(2)HPS](2+)+PDDAC) cations and poly(styrenesulfonate) (PSS) anions were used to fabricate thin films via layer-by-layer deposition processes on quartz and glass substrates, the emission intensity of [H(2)A(2)HPS](2+) showed linear relationship with the number of ([H(2)A(2)HPS](2+)+ PDDAC)/PSS bilayers, due to the uniform co-deposition of [H(2)A(2)HPS](2+) cations into the PDDAC/PSS bilayers. This proves that the AIE fluorophore is an excellent probe for monitoring the layer-by-layer self-assembling processes of the polyelectrolytes on various substrates. (C) 2008 Elsevier B.V. All rights reserved