Hyperbranched Conjugated Polysiloles: Synthesis, Structure, Aggregation-Enhanced Emission, Multicolor Fluorescent Photopatterning, and Superamplified Detection of Explosives

Hyperbranched poly(2,5-silole)s [hb-P1(m), m = 1, 6] are synthesized for the first time in this work. 1,1-Dialkyl-2,5-bis(4-ethynylphenyl)-3,4-diphenylsiloles [1(m)] were polymerized by TaBr5, affording hb-P1(m) with high molecular weights (Mw up to 2.5 × 105) in high yields (up to 98%). The structures of hb-P1(m) were characterized by spectroscopic methods and the degree of branching of hb-P1(6) was determined to be 0.55. The hyperbranched polymers are soluble and stable, with no changes in solubility observed after they have been stored under ambient conditions for more than two years. Absorption and emission spectra of hb-P1(m) are red-shifted from those of 1(m), indicating that the polymers are more conjugated than the monomers. Both 1(m) and hb-P1(m) are nonemissive or weekly fluorescent when dissolved in their good solvents but become highly emissive when aggregated in their poor solvents or fabricated into thin solid films, showing unusual phenomena of aggregation-induced (AIE) and -enhanced emissi...