Quantum Yield Studies of Singlet Oxygen Production by Bis-cyclometalated Ir(III) Complexes

Overview

Objectives/Goals To measure the quantum yields of singlet oxygen production of five bis-cyclometalated Ir(III) complexes. Methods/Materials Five Iridium(III) complexes (BSNIr*, BSNIrG, BTIrPy, BTIrG, and FIrPic) were investigated for their quantum yields of singlet oxygen production through time-resolved infrared luminescence spectroscopy. Quantum yields were obtained in various solvents. Quenching rates were also measured by similar principles. Results At 532 nm in benzene, the quantum yield of singlet oxygen production of BSNIrG (Quantum yield = 0.81), BTIrPy (Quantum yield = 0.95), and BSNIr* (Quantum yield = 0.77) are all above those of our standard, TPP (Quantum yield = 0.62), whereas BTIrG (Quantum yield = 0.43) are below our standard. At 355 nm in benzene, the quantum yield of FIrPic (Quantum yield = 1.0) and BTIrPy (Quantum yield = 0.96) are above those of our standard, TPP (Quantum yield = 0.62), whereas BSNIr* (Quantum yield = 0.60), BSNIrG (Quantum yield = 0.54), and BTIrG (Quantum yield = 0.50) are below our standard. Conclusions/Discussion Comparison of quantum yields in benzene shows that FIrPic has the greatest quantum yield. The decrease of FIrPic's quantum yield in methanol (Quantum yield = 0.46) indicates that H-bonding stabilizes its first excited state. There seems to be some correlation between a red shifted sensitizer, which has a high quantum yield, and a more blue shifted sensitizer, which has a considerably lower quantum yield.

Competition history

• CSEF 2003 Chemistry · Entry S0508

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