Synthesis, photophysical and oxygen-sensing properties of a novel bluish-green emission Cu(I) complex

A novel copper(I) complex [Cu(POP)(PTZ)]BF4 (POP = bis[2-(diphenyl-phosphino)phenyl]-ether, PTZ = 5-(2-pyridyl)tetrazole) has been synthesized and characterized by elemental analysis, 1H NMR and IR. Complex [Cu(POP)(PTZ)]BF4 shows bright bluish-green emission centered at 495 nm in solid-state at room temperature, arising from metal to ligand charge-transfer (MLCT) transition. The photoluminescence quantum yield measured in air is 0.12. The excited state lifetime of [Cu(POP)(PTZ)]BF4 is on the order of microsecond indicating the presence of phosphorescent emission. The emission intensity of [Cu(POP)(PTZ)]BF4 appears to be highly sensitive to the O2 concentration, meaning it possesses oxygen-sensing property. The sensing performances of [Cu(POP)(PTZ)]BF4/MCM-41 composite materials are evaluated and the system with 20 mg/g loading level exhibits the best sensitivity (I0/I100 > 11), and the shortest response time (t↓ < 5 s), which is attractive because copper(I) complexes are nontoxic and can be prepared at a fraction of the cost of noble metal-based ones.