An iridium complex-based phosphorescent probe for recognition to bisulfite and cyanide in neutral aqueous system

A newly designed cyclometalated iridium complex Ir(mepi)(ppy)(2) (2, Hppy= 2-phenylpyridine, Hmepi = 3,3-dimethy1-1-ethy1-2-(4-(pyridin-2-y1)styryl)indolium iodide (1)) was successfully synthesized for the rapid detection of HSO3- and CN-. For complex 2, it is interesting that the selective 1,4-addition reaction with HSO3- in aerated DMSO/PBS buffer can be visualized by intense turn-on green emission. However, the 1,2-addition reaction with CN- resulted in an emission color change from colorless to orange-yellow. Furthermore, the limits of detection for HSO3- and CN- were calculated as low as 0.049 and 0.15 mu[M, respectively. The results indicate that the two anions can be detected selectively and separately by naked-eyes in neutral aqueous system. As the typical interfering anion for detecting HSO3-,HS- led to the almost similar emission change that was caused by HSO3-. As a result, the reaction between 2 and HS- could be assigned as 1,4-addition rather than 1,2-addition reaction, which was further confirmed by the 1H NMR spectra changes of the ligand with these representative anions (HSO3-, HS- and CN-). (C)2017 Elsevier B.V. All rights reserved.