Catalytic hydrosilylation routes to divinylbenzene bridged silole and silafluorene polymers. Applications to surface imaging of explosive particulates

The syntheses, spectroscopic characterization, and fluorescence quenching efficiencies of 1,1silole- and 1,1-silafluorene-phenylenedivinylene polymers are reported. Model dimeric metallole compounds containing a phenylenedivinylene bridge have been synthesized to provide detailed structural and spectroscopic insight into conformational effects and electron delocalization. Poly((tetraphenyl)silole-phenylenedivinylene) and poly(silafluorene-phenylenedivinylene) both maintain-a regioregular trans-vinylene Si-C backbone with sigma*-pi/pi r* conjugation. Various hydrosilylation catalysts were screened to evaluate their ability to produce high molecular weight polymers and to direct a strictly trans product. Molecular weights (M(w)) for these polymers are in the range of 8400-9600. Fluorescence spectroscopy shows a significant bathochromic shift for the silafluorene polymer from solution to the solid state. A surface detection method for the analysis of solid particulates of TNT, DNT, PA, RDX, HMX, Tetryl, TNG, and PETN by fluorescence quenching was explored. The blue-emitting silafluorene polymer exhibited improved sensitivity for detecting explosive particle residues as compared to previously reported metallole polymers. Detection limits as low as 100 pg cm(-2) for TNT are obtained. The Stern-Volmer equation quantitatively models the fluorescence quenching of these polymers by TNT, RDX, and PETN in thin solid-state films.