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

Abstract 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.