Interfacial electronic coupling in copper 4-cyanophenylacetylide/copper phenylacetylide regulates molecular oxygen...

Interfacial regulation of molecular oxygen activation is critical for controlling reactive oxygen species generation in photocatalytic systems. Here, a copper 4-cyanophenylacetylide/copper phenylacetylide heterointerface (CN-PhC₂Cu/PhC₂Cu) was constructed through a one-step in situ strategy to regulate interfacial charge transfer and excited-state processes. Cyano functionalization created an electronic difference between the two copper acetylide components, while their related CCCu coordination frameworks favored intimate interfacial coupling. The optimized 75CNPC removed 95.2 ± 3.9% of diclofenac within 60 min under 455 nm visible-light irradiation and retained appreciable activity in the presence of common water constituents and in different aqueous matrices. Optical, electrochemical, and theoretical analyses indicate that interfacial coupling modulates the local electronic structure, facilitates charge separation, and strengthens O₂ adsorption. Reactive oxygen species (ROS) measurements further reveal a redistribution of O₂ activation channels: electron transfer contributes to ·O₂^- formation, whereas interface-regulated excited-state processes favor triplet-mediated energy transfer and enhanced ¹O₂ generation. Liquid chromatography-mass spectrometry (LC-MS) analysis and toxicity evaluation suggest that DCF undergoes initial activation, structural fragmentation, and progressive oxidation, with several identified transformation products exhibiting reduced predicted toxicity relative to the parent compound. These results demonstrate how the CN-PhC₂Cu/PhC₂Cu coordinates charge transfer, excited-state evolution, and molecular oxygen activation in organometallic photocatalysts.