Charge Separation to Facilitate the Conversion of Copper-Phenylacetylide from Aggregation-Induced Emission to Efficient Photocatalysis

Aggregation-induced emission (AIE) materials are considered promising photocatalyst candidates due to their robust light-harvesting and efficient photoexcitation, if their photoexcited carriers can be separated effectively. Herein, by skillfully selecting multi-alkynyl ligands instead of phenylacetylene to construct multi-channel charge separation, copper-phenylacetylide (CP-1) with AIE properties is successfully transformed into efficient photocatalysts CP-2P (copper-1,4-diethynylbenzene) and CP-2M (copper-1,3-diethylnylbenzene). In these structures, the multi-alkynyl ligands connects the copper-ladder into multi-dimensional metal-organic frameworks with greatly reduced bandgap, enhances charge transfer and separation, and facilitated oxygen adsorption and activation. As a representative, CP-2P has the best photocatalytic activity and stability for photocatalytic aerobic oxidation, such as thioanisole oxidation (conv. > 99%, methyl phenyl sulfoxide sel. (sic) 94%), benzyl alcohol oxidation (conv. > 99%, benzaldehyde sel. > 99%) and benzylamine oxidation (conv. > 99%, N-benzylidene benzylamine sel. > 99%), which can be used for large-scale sunlight-driven organic photosynthesis. This work confirms the feasibility of controlled conversion of the conventional copper-alkynyl from AIE material to efficient photocatalyst using charge separation strategy, which provides an important guidance for the rational design of new high-efficiency photocatalyst.