Polyelectrolyte matrix-enabled multi-step energy transfer light-harvesting system for enhanced photocatalytic benzimidazole synthesis

Abstract

Natural photosynthesis system is characterized by a multi-step sequential energy transfer process, and the construction of an efficient and sequential artificial light-harvesting system (ALHS) to simulate natural photosynthesis has become a research hotspot. In this study, we developed and constructed a supramolecular self-assembly system through electrostatic interactions between the positively charged methylpyridine-modified cyanide-substituted phenylethylene derivative (DCMI) and the negatively charged polyelectrolyte material sodium polyphenylene sulfonate (RSS), which exhibited obvious fluorescence enhancement in the polyelectrolyte matrix and could be used as an energy donor to construct a multi-step sequential energy transfer system. By employing three different fluorescent dyes, namely, rhodamine B (RhB), sulforhodamine 101 (SR101), and cyanine 5 (Cy5), as energy acceptors, energy could be transferred sequentially from DCMI-RSS to RhB, SR101, and Cy5, showing significant energy transfer efficiency of the ALHS. Notably, the production of superoxide anion radicals (O₂˙⁻) gradually increased in the multi-step energy transfer system. Furthermore, to fully utilize the collected energy and generated O₂˙⁻, the ALHS promoted the photooxidation reaction of phenylenediamine and benzaldehyde for the photocatalytic synthesis of benzimidazole with an extremely high yield. This study provides useful insights into the construction of ALHSs based on polyelectrolyte frameworks.