Iridium(III) complex-based electrochemiluminescent probe for H2S

Abstract

Hydrogen sulfide (H2S) is a toxic gaseous molecule with an unpleasant rotten egg smell. As abnormal levels of H2S correlate with various diseases, rapid, sensitive and simple detection methods are highly required. Electrochemiluminescence (ECL) based chemosensors provide several advantages, allowing simple analysis with a time and cost efficient manner. With these features, it can be miniaturized available for point-of-care-testing (POCT) detection sensor. In this study, we designed a new electrochemiluminescent chemodosimetric probe 1 for H2S based on cyclometalated Iridium(III) complexes. o-(azidomethyl)benzoyl group on the main ligands reacts selectively with H2S, inducing cascade reaction of hydrosulfide-mediated reduction and intramolecular cyclization cleavage. With this structural change by H2S, the ECL intensity of 1 decreased greatly due to the unfavorable electron transfer of TPA radical. Probe 1 showed high turn-off ratio of ECL and good selectivity for H2S over anions and biothiols. The mechanism study for sensing H2S was performed by using 1H NMR and MALDI-TOF spectroscopies.