Tuning Photophysical and Electrochemical Properties of Cationic Iridium(III) Complex Salts with Imidazolyl Substituents by Proton and Anions

A series of cationic iridium(III) complex salts, 1−5, were synthesized containing different phenanthroline derivatives. Their photophysical and electrochemical properties were investigated. The influences of anions and proton on the photophysical and electrochemical properties were also studied in detail. Upon addition of CF₃COOH, the emission wavelength was significantly red-shifted and the emission color changed from yellow to red. In addition, the addition of F^-, CH₃COO^-, and H₂PO₄^- can also cause significant variations in UV−vis absorption and emission spectra. Upon addition of F^-, CH₃COO^-, and H₂PO₄^-, the solution colors of 1−3 changed from yellow-green to brown and the emission of 1−3 was quenched completely, which can be observed by the naked eye.