A green-emitting Cu complex for oxygen-sensing purpose: Synthesis, characterization and photophysical features

• A green-emitting Cu(I) complex was reported for oxygen sensing purpose.
• π–π attraction within complex molecules was eliminated to favor O2 sensing.
• Sensing composite was constructed using MCM-41 as supporting matrix.
• Short response time of 10 s and sensitivity of 5.56 were obtained.

In the present work, a green-emitting Cu(I) complex [Cu(BT-Et)(POP)]BF4 was synthesized and fully characterized, where BT-Et = 4-(1-ethyl-1H-benzo[d]imidazol-2-yl)thiazole, POP = bis(2-(diphenylphosphanyl)phenyl) ether, respectively. An ethyl group was connected onto the diamine ligand to breach π–π attraction within solid [Cu(BT-Et)(POP)]BF4, favoring O2 molecule attack and sensitivity improvement. Its molecular identity was confirmed by single crystal analysis and theoretical calculation. [Cu(BT-Et)(POP)]BF4 emitted long-lived green emission peaking at 521 nm upon photoexcitation which was vulnerable towards O2 molecule, making itself a potential oxygen sensing material. [Cu(BT-Et)(POP)]BF4 was then doped into a silica supporting matrix MCM-41. The resulting composite samples showed sensing behavior towards O2 molecule, with short response time of 10 s and sensitivity of 5.56.

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