Modulation of the oxygen sensing properties of iridium (III) complexes by changing their substitution groups

Abstract

In this study, new bis-cyclometalated iridium (III) complexes bearing different ligated groups (–H, –OCH3, –F, –CH3) at the aryl moiety (Ir-1, Ir-2, Ir-3 and Ir-4) were synthesized and characterized. Then oxygen sensing properties of corresponding complexes were investigated in EC film. The complexes showed room temperature phosphorescence spectra in the range of 562–590 nm in THF and 546–554 nm in ethyl cellulose (EC) matrix. When they were incorporated in an ethyl cellulose matrix, the probes showed optimal dynamics of luminescence for oxygen monitoring in the range from 0 % to 100 % air saturation. The I0/I100 values of Ir-1, Ir-2, Ir-3 and Ir-4 in EC thin film were calculated as 10.9, 5.0, 7.3 and 22.7, respectively. The results showed that the oxygen sensitivity accomplishment of the complex core can be fine-tuned by varying these ligated groups, and the weak electron-donating properties of the methyl groups at the aryl moiety improve remarkably the optical oxygen sensing abilities of the Iridium (III) complexes.