Multifunctional poly(N-sulfonylamidine)s constructed by Cu-catalyzed three-component polycouplings of diynes, disulfonyl azide, and amino esters

The development of efficient multicomponent polymerization (MCP) to prepare heteroatom-rich macromolecules, especially those with complicated structures and multifunctionality, is gathering increasing research interest from chemists. In this work, we report a facile one-pot three-component polymerization method to prepare multifunctional polymers. The Cu-catalyzed polycoupling reactions of aromatic diynes, disulfonyl azide, and optically active amino esters proceeded in a mild manner under room temperature, furnishing regular poly(N-sulfonylamidine)s with high molecular weights (M_w up to 35 900) and in satisfactory yields (up to 87%). The model compound was synthesized to verify the complete transformation from monomers to the desired polymeric products. All the polymers possess excellent solubility in common organic solvents, good film-forming ability, and high thermal stability. The backbones of the polymers are induced to helically rotate by the optically active chiral amino esters, resulting in the circular dichroism (CD) absorption in the solutions and cast films. The polymers are almost nonemissive in solutions, whereas their nanoaggregates or thin films fluoresce intensely upon photoexcitation, showing a unique phenomenon of aggregation-induced emission (AIE). The thin films of these polymers possess high refractive indices (RI = 1.7327-1.6419) in a wide wavelength region of 400-893 nm and low optical dispersions (D down to 0.0247). Well-resolved two-dimensional fluorescent photopatterns can be generated by UV irradiation of these thin films via a copper photomask in air. This work provides an efficient approach toward synthesizing multifunctional heteroatom-rich polymeric materials, overcoming the drawbacks of conventional polymerizations.