Rational Design of Phosphorescent Chemodosimeter for Reaction-Based One- and Two-Photon and Time-Resolved Luminescent Imaging of Biothiols in Living Cells

A selective phosphorescent biothiols probe is synthesized based on Ir(III) complex 1, which has 2,2′‐biquinoline as the N^N ligand for realizing the satisfied two‐photon absorption cross‐section and two‐functionalized 2‐phenylpyridine ligands with an α,β‐unsaturated ketone moiety as the thiol reaction site. The one‐ and two‐photon optical properties of 1 are investigated through UV–vis absorption spectrum and photoluminescence spectrum. This Ir(III) complex can act as an excellent one‐ and two‐photon excited “OFF–ON” phosphorescent probe for biothiols based on the 1,4‐addition of biothiol to α,β‐unsaturated ketones. Moreover, one‐ and two‐photon‐induced luminescent imagings of biothiols in living cells are also realized. Furthermore, the experiments of time‐resolved photoluminescence technique and fluorescence lifetime imaging microscopy demonstrate that 1 is able to detect biothiols in the presence of strong background fluorescence. In addition, probe 1 is adsorbed into the shell of mesoporous silica nanoparticles with core–shell structure to form a nanoprobe, which can realize the ratiometric detection of biothiols in absolute water solution and living cells based on two phosphorescent signals. A multifunctional phosphorescent chemodosimeter based on an Ir(III) complex acts as a one‐ and two‐photon‐induced “OFF–ON” luminescent switch and a naked‐eye perceivable probe for detection of biothiols based on 1,4‐addition of biothiols to α,β‐unsaturated ketone in living cells, and also can be used in time‐resolved luminescent sensing and fluorescence lifetime imaging of biothiols in living cells.