Silole-containing poly(silylenevinylene)s: Synthesis, characterization, aggregation-enhanced emission, and explosive detection
Description
Hydrosilylation polymerizations of 1,1-dimethyl-2,5-bis(4-ethynylphenyl)-3,4-diphenylsilole with aromatic silylhydrides including 1,4-bis(dimethylsilyl)benzene, 4,4′-bis(dimethylsilyl)biphenyl, 2,5-bis(dimethylsilyl)thiophene, and 2,7-bis(dimethylsilyl)-9,9-dihexylfluorene in the presence of Rh(PPh3)3Cl catalyst in refluxed tetrahydrofuran afford a series of silole-containing poly(silylenevinylene)s. Under optimum condition, the alkyne polyhydrosilylation reactions progress efficiently and regioselectively, yielding polymers with high molecular weights (Mw up to 95,300) and good stereoregularity (E content close to 99%) in high yields (up to 92%). The polymers are processable and thermally stable, with high decomposition temperatures in the range of 420−449 °C corresponding to 5% weight loss. They are weakly fluorescent in the solution state but become emissive in the aggregate and film states, demonstrating their aggregation-enhanced emission characteristics. The explosive sensing capabilities of the polymers are examined in both solution and aggregate states. The emissions of the polymers aggregates in aqueous mixture are quenched more efficiently by picric acid in an exponential pattern with high quenching constants (up to 27,949 L/ mol), suggesting that the polymers aggregates are sensitive chemosensors for explosive detection.
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