Construction of Functional Macromolecules with Well-Defined Structures by Indium-Catalyzed Three-Component Polycoupling of Alkynes, Aldehydes, and Amines

We present here a new programmable polymerization route for the synthesis of new conjugated polymers via one-pot reaction route. The three-component polycoupling reactions of terephthalaldehyde and dibenzylamine with 4,4′-diethynyl-1,1′-biphenyl, bis(4-ethynylphenyl)dimethylsilane, 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene, N,N-bis(4-ethynylphenyl)aniline, or 2,5-bis(4-ethynylphenyl)-1,1-dimethyl-3,4-diphenylsilole are catalyzed by indium(III) chloride in o-xylene at 140 °C, affording soluble polymers with well-defined structures and high molecular weights (Mw up to 51 200) in high yields (up to 96.9%). Model reaction was carried out to elucidate the chemical structures of the polymers. The resulting polymers are processable and enjoy high thermal stability. The polymers carrying tetraphenylethene and silole units are weakly emissive in solutions but become strong emitters when aggregated in poor solvents or fabricated as thin films in the solid state, displaying a phenomenon of aggregation-enhanced emission characteristic. Thin films of the polymers show high refractive indices (n = 1.7529–1.6041) in a wide wavelength region of 400–1600 nm with low optical dispersions (D′ down to 0.005). The polymers are readily metallified by complexation of their triple bonds with cobalt octacarbonyls. Pyrolysis of the resulting organometallic polymers at high temperature under inert atmosphere generates nanostructured ceramics with high magnetic susceptibility (Ms up to 80.7 emu/g) and near-zero coercivity (Hc down to 0.19 kOe).