Design And Synthesis Of Phosphorescent Iridium(Ⅲ) Complexes Probes And Their Biological Applications

Among various classes of luminophores, phosphorescent transition-metal complexes possess excellent photophysical properties, such as evident Stokes shifts for easy separation of excitation and emission, and relatively long emission lifetime of phosphorescent signals. Among all kinds of phosphorescent transition-metal complexes, iridium(III) complexes are regarded as the most excellent phosphorescent materials due to their high photoluminescence efficiency and excellent color tunability. Thus, it is anticipated that such a class of phosphorescent materials could be used as appealing candidates for biosensing and bioimaging.We designed and synthesized small-molecule phosphorescent iridium(III) complexes with functional groups. These are used to detect biological thiols in aqueous solution. Then a selective phosphorescent ratiometric probe is synthesized based on the iridium(III) complex soft salt. And we study applications in biosensing and cell imaging. The main works as follow:1. We designed and synthesized a small molecule phosphorescent iridium(III) complex probe Ir1, which has an α,β-unsaturated ketone moiety as the thiol reaction site. The optical properties of the probe are investigated through UV-vis absorption spectrum and photoluminescence spectrum.This iridium(III) complex can act as an excellent “OFF-ON” phosphorescent probe for biothiols based on the 1,4-addition of biothiol to α,β-unsaturated ketones. Moreover, one- and twophoton-induced luminescent imagings of biothiols in living cells are also realized. Furthermore, the experiments of luminophor lifetime imaging demonstrate that the probe is able to detect biothiols in the presence of strong background fluorescence.2. We synthesized a selective phosphorescent ratiometric soft salt probe, which was designed based on the iridium(III) complex Ir1. The resulting “soft salt” complexes are composed of an organometallic cation and an organometallic anion. The optical properties of the probe are investigated through UV-vis absorption and photoluminescence spectrum. And we can realize the ratiometric detection of biothiols in water solution and living cells based on two phosphorescent signals.