In Situ Generation of N-Heteroaromatic Polymers: Metal-Free Multicomponent Polymerization for Photopatterning, Morphological Imaging, and Cr(VI) Sensing

Electron-deficient N-heteroaromatic polymers are crucial for the high-tech applications of organic materials, especially in the electronic and optoelectronic fields. Thus, the development of new polymerizations to afford adaptable electron-donating–accepting scaffolds in N-heteroaromatic polymers is in high demand. Herein, we have developed metal-free multicomponent polymerizations of diynes, diamines, and glyoxylates successfully for in situ generation of poly(quinoline)s with high molecular weights (M_w up to 16,900) in nearly quantitative yields. By tuning the electron distributions of the polymer backbones, the resulting poly(quinoline)s showed various aggregation-induced behaviors and photoresponsive abilities: The thin films of the poly(quinoline)s could be fabricated readily into well-resolved photopatterns by photolithography techniques. They could be utilized as fluorescent probes to visualize the morphologies of polymer materials directly; these include spherulites and microphase separation of polymer blends. Their nanoparticles demonstrated sensitive and highly selective fluorescence quenching to hexavalent chromium ion Cr(VI), thereby providing access for biological imaging of Cr(VI) in unicellular algae.