Development And Application Of The Transition Metal Complexes-based Multisignal Probes

Although considerable efforts have been made for the development of transition metal complexes chemosensors, the multisignal chemosensor using transition metal complexes as the reporter is scarce. For the outstanding photophysical, photochemical and electrochemical properties, and also good cell penetrability and biocompatibility about Ru(?) and Ir(?) complexes, Ru(?) and Ir(?) complex-based luminescence probes for bioactive molecules were successfully designed and synthesized by introducing different recognition groups of ligands.First, a new ruthenium(?) complex-based multisignal chemosensor, Ru-Fc, is designed for the highly sensitive and selective detection of lysosomal hypochlorous acid (HOC1). Ru-Fc is weakly luminescent because the MLCT (metal-to-ligand charge transfer) state is corrupted by the efficient photoinduced electron transfer (PET) process from Fc (ferrocene) moiety to Ru(?) center. The cleavage of Fc moiety by a HOCl-induced specific reaction leads to elimination of PET, which re-establishes the MLCT state of the Ru(?) complex, accompanied by remarkable photoluminescence (PL) and electrochemiluminescence (ECL) enhancements with good linearity, low detection limit and selectivity. Furthermore, the probe can quickly enter the cells and tissues and can detect HOCl in lysosomal and in vivo Daphnia magna. The results showed it owes good cell permeability and biological compatibility. Ru-Fc is a new HOCl chemosensor in the integration of many advantages including photoluminescence and electrochemiluminescence dual-signal, cellular lysosomal targeting and live application. This study may open up a new direction and a broader space for the development of molecular probes.In addition, a novel irdium(?) complex-based phosphorescence probe, [Ir(ppy)2(DA-phen)]PF6, has been sythensized as photoluminescent (PL) and electrochemiluminescent (ECL) dual-signaling probe for the detection of nitric oxide (NO) by introducing 1,10-Phenanthroline-5,6-diamine (DA-phen) ligand. The PL and ECL intensities of [Ir(ppy)2(DA-phen)]PF6 are very weak, but the remarkable enhancements in PL and ECL intensities were observed after the probe reacted with NO solutions in the air. The probe has a lot of advantages including large Stokes shifts, high sensitivity, low detection limit, rapid response, good selectivity, wide application range of pH, PL and ECL dual-signaling response, which enabled it to be used for visualizing NO in live HepG2 cells and in vivo Daphnia magna. This probe has more superiorities of the reliable, efficient and rapid detection for NO than the ruthenium complex-based probe.