C–H Activation-Based Multicomponent Polyannulations toward Fluorescent Heteroaromatic Polyelectrolytes for Sunlight-Driven Antibacterial Coatings

The development of facile and efficient synthetic methods for functional polyelectrolytes bearing charges on main chains is an important, yet challenging task. Herein, we develop a straightforward C–H activation-based multicomponent polyannulation method that can efficiently transform readily available internal diynes, aldehydes, and amines into diverse functional main-chain charged polyelectrolytes with high molecular weights (Mw up to 55000 g/mol) in high yields of up to 99.2%. Multisubstituted polycyclic heteroaromatic cations are generated in situ in polymer backbones as π spacers via successive C–H activation/annulation processes in a one-pot manner, which are hard to achieve by conventional methods. Benefiting from the unique structures, the obtained polyelectrolytes all exhibit excellent solubility and film-forming ability, high thermal and morphological stability, and readily tunable aggregate-state luminescence properties. Remarkable light-enhanced bactericidal activity against Gram-positive bacteria was achieved due to the efficient reactive oxygen species generation capability of the polycations. Furthermore, the polyelectrolyte thin films can function as good sunlight-triggered antibacterial coating materials on various substrates, demonstrating application potential for the gentle sunlight sterilization of medical facilities.