2,3,4,5-Tetraphenysilole-Based Small Molecules And Functional Polymers:Synthesis, Characteriz-ation And Applications

Silole-based π-conjugated compounds and their polymers have been actively studied as promising electroluminescent materials because of their unique electronic structure (low-lying LUMO level), formed by σ*-π*conjugation. In this thesis, we synthesized and characterized three kinds silole-containing compounds, the main results are outlined as follows:In the first chapter, we present the synthesis and characterization of a novel series of σ*-π*conjugated silole-containing poly(silylenevinylene)s (P1/5-P4/5). Under optimum condition, the alkyne polyhydrosilylation reactions progress in high yields (up to92%). The polymers are processable and thermally stable, with high decomposition temperatures in the range of420-449℃corresponding to5%weight loss. The P1/5-P3/5lose5%of their weights (Td) at441-449℃, which are higher than that of P4/5(420℃). Moreover, P1/5-P3/5remain about60%weight even at temperatures up to750℃, which is attributive to their high silicon contents and/or possible cross-linking reaction. Such good thermal properties reveal their potential utility as ceramic precursors. They are weakly fluorescent in the solution state but become emissive in the aggregate and film states, demonstrating their aggregation-enhanced emission (AEE) characteristics. The emissions of the polymers aggregates in aqueous mixture are quenched more efficiently by picric acid (PA) in an exponential pattern with high quenching constants (up to27949L mol-1), suggesting that the polymers aggregates are sensitive chemosensors for explosive detection.In the second chapter, we present the synthesis and characterization of silole-containing linear and hyperbranched D-A conjugated polymersith triphenylamine as electron-donor (D) and silole as electron-acceptor (A). They exhibited high thermal stability (5%weight loss at～400℃) and show aggregation-enhanced emission characteristics accompanied by intramolecular charge transfer effect.In the third chapter, we present synthesis and characterization of two naphthyl substituted compounds based on2,3,4,5-tetraphenysilole. The conjugation of the molecules is elongted and the molecules become more rigidity when the naphthalene moieties are introduced to2,3,4,5-tetraphenysilole. The thermal stability is also improved with decomposition temperatures at400℃. The greatly enhanced emission efficiencies of the compounds in the solid state suggest that they are of aggregation-induced emission (AIE) characteristics. The phenomenon suggests that the attachment of naphthalene moiety can’t change the AIE characteristics of silole unit. Experimental and theoretical studies show that β-naphthyl substituted compouds have smaller bandgap than a-naphthyl substituted compounds, rendering redshifts in UV and fluorescence spectra.