Catalyst-free Polyannulations of Potassium Sulfide and Unactivated Alkynes toward Multifunctional Thiophene-Containing Polymers

Abstract

Facile and efficient transformation of inexpensive inorganic sulfides into high-value polymer materials is of great academic and industrial significance. Herein, we report a catalyst-free polyannulation strategy between potassium sulfide and internal diynes, which can efficiently produce thiophene-containing polymers (TCPs) in N,N-dimethylformamide under mild conditions. The reaction may proceed via a trisulfur radical anion-mediated mechanism, generating thiophene units in situ without the need for thiophene-containing monomers, additives, or transition metals. The resulting TCPs exhibit high molecular weights (up to 16,300 g/mol), excellent solubility and film-forming ability, and remarkable thermal stability. Their thin films display high refractive indices (n589.2 = 1.6579–1.8078) and UV-tunable optical properties. Post-oxidation transforms the polymers into aggregation-induced emission-active materials with remarkably enhanced fluorescence quantum yields in aggregate and solid states. The aggregate-state luminescent TCPs and their S,S-dioxide derivatives demonstrate organelle-specific imaging capabilities and excellent biocompatibility, highlighting their potential for advanced optical and bioimaging applications.