Efficient green electrogenerated chemiluminescence from cyclometalated iridium(III) complex

• A cyclometalated iridium(III) complex, (dfppy)2Ir(PyBiz), was synthesized and characterized.
• Intense green ECL emissions from (dfppy)2Ir(PyBiz) were observed in annihilation and coreactant processes.
• Green ECL emission of (dfppy)2Ir(PyBiz) can be distinguished from red emission of Ru(bpy)32 + in a mixed solution.

A novel cyclometalated iridium(III) complex, (dfppy)2Ir(PyBiz), was synthesized by using 2-(2,4-difluorophenyl)pyridine (dfppy) as the C^N main ligand and 2-(2-pyridyl)benzimidazolato-N,N′ (PyBiz) as the N^N ancillary ligand. The photophysical, electrochemical and electrogenerated chemiluminescence (ECL) properties of (dfppy)2Ir(PyBiz) were investigated. (dfppy)2Ir(PyBiz) shows a green photoluminescence emission with a maximum wavelength at 527 nm and quasi-reversible redox behaviors in acetonitrile solvent. Intense green ECL emissions that could be seen with the naked eyes were observed in annihilation and coreactant processes and the ECL spectra generated from three processes are identical to its photoluminescence spectrum, indicating that the same excited state is formed in these processes. The green ECL emission of (dfppy)2Ir(PyBiz) can be distinguished from the red emission of Ru(bpy)32 +, which provides the possibility of the identification of (dfppy)2Ir(PyBiz) and Ru(bpy)32 + in a single solution containing both compounds. The green ECL emission of (dfppy)2Ir(PyBiz) with high ECL efficiency makes it promising to develop ECL luminophore for multiple wavelength and potential use in multichannel analytical applications.

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