Stille type P-C coupling polycondensation towards phosphorus-crosslinked polythiophenes with P-regulated photocatalytic hydrogen evolution

• Published in: Chemical science (Cambridge) 2023-03, Vol.14 (11), p.299-2998
• Main Authors: Zhang, Zhikai, Zhang, Boyang, Han, Xue, Chen, Hongyi, Xue, Cece, Peng, Min, Ma, Guijun, Ren, Yi
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Carbon; Chemistry; Coupling; Crosslinking; Crosslinking polymerization; Functional materials; Halides; Harnesses; Hydrogen evolution; Light irradiation; NMR; Nuclear magnetic resonance; Phosphorus; Photocatalysis; Polymerization; Polymers; Polythiophene
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d2sc06702a

Recently, exploring new type polymerization protocols has been a major driving force in advancing organic polymers into highly functional materials. Herein we report a new polycondensation protocol to implant the phosphorus (P) atom in the main backbone of crosslinked polythiophenes. The polycondensation harnesses a Stille phosphorus-carbon (P-C) coupling reaction between phosphorus halides and aryl stannanes that has not been reported previously. Mechanistic studies uncovered that the P-electrophile makes the reactivity of a catalytic Pd-center highly sensitive towards the chemical structures of aryl stannanes, which is distinct from the typical Stille carbon-carbon coupling reaction. The efficient P-C polycondensation afforded a series of P-crosslinked polythiophenes (PC-PTs). Leveraging on the direct P-crosslinking polymerization, solid-state 31 P NMR studies revealed highly uniform crosslinking environments. Efficient post-polymerization P-chemistry was also applied to the PC-PTs, which readily yielded the polymers with various P-environments. As a proof of concept, new PC-PTs were applied as the photocatalysts for H 2 evolution under visible light irradiation. PC-PTs with an ionic P(Me)-center exhibit a H 2 evolution rate up to 2050 μmol h −1 g −1 , which is much higher than those of PC-PTs with a P(O)-center (900 μmol h −1 g −1 ) and P( iii )-center (155 μmol h −1 g −1 ). For the first time, the studies reveal that regulating P-center environments can be an effective strategy for fine tuning the photocatalytic H 2 evolution performance of organic polymers. New type of Stille type phosphorus-carbon polycondensation was developed to access phosphorus-crosslinked polythiophenes where regulating P-center environments can be an effective strategy for fine tuning the photocatalytic H 2 evolution performance.