Synthesis of fluorescent poly(silyl indole)s via borane-catalyzed C–H silylation of indoles

The development of a new polymerization strategy is essential for the design and synthesis of polymers with new frameworks, since it would effectively expand the diversity of the structures and properties of polymers. Here we report a metal-free B(C₆F₅)₃-catalyzed step-growth polymerization of indoles and hydrosilanes through regioselective dehydrogenation silylation of indoles. A series of indole and silyl-based monomers were designed and synthesized for the preparation of linear poly(silyl indole)s with good solubility through AA + BB-type or AB-type polymerization. In addition, we employed trisilane and biindole as building blocks to construct hyperbranched polymers with rigid structures. All the obtained polymers were fully structurally characterized and observed to fluorescently emit strong bright blue-violet light in both solution and in the solid state under UV light. These poly(silyl indole)s with their novel type of structure demonstrated very promising application potentials in organic optoelectronic materials.