Di-/trinuclear cationic Ir(III) complexes: Design, synthesis and application for highly sensitive and selective detection of TNP in aqueous solution

•Novel multinuclear Ir(III) complexes with different bridging ligands are designed.•Strong emissions in the aggregation states are observed.•Highly selective and sensitive detection of TNP in aqueous media is achieved using them as sensors.

Novel di- and trinuclear cationic iridium(III) complexes with flexible chain functionalized triazole-pyridine moieties as bridging ligands, namely DC-Ir and TC-Ir, were successfully synthesized and their photophysical and electrochemical properties studied. Despite DC-Ir and TC-Ir have different numbers of iridium(III) cores, the almost identical emissions in both solutions and aggregation states were observed. Theoretical calculations were performed to investigate their electronic structures and rationalize the photophysical and electrochemical behaviors. Compared with the emission in the solution, they exhibit enhanced photoluminescence in the aggregation states. Benefiting from the high emission in aqueous solution, DC-Ir and TC-Ir were employed as the “turn-off” sensors to detect the explosives. The results reveal that DC-Ir and TC-Ir show fast and highly sensitive and selective detection towards 2,4,6-trinitrophenol (TNP) owing to the efficient photo-induced electron transfer as well as the strong electrostatic interaction.

Graphical abstractNovel di- and trinuclear cationic Ir(III) complexes with flexible chain functionalized triazole-pyridine moieties as bridging ligands were successfully designed and employed as the fast and highly sensitive and selective sensors towards TNP.Download high-res image (183KB)Download full-size image