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 1,1-silole− 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 σ*−π/π* 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.