Exploitation of the Dual-emissive Properties of Novel Luminescent Iridium(III) Polypyridine Complexes in the Development of Biological Sensory Systems

The aim of this project is the design of novel dual-emissive luminescent iridium(III) polypyridine complexes for use as the next generation of biological probes. On the basis of their rich photophysical properties, there has been a fast-growing interest in the utilization of iridium(III) polypyridine complexes as luminescent sensors for various analytes. However, the emission profiles and spectral characteristics of these luminescent probes basically remain the same upon analyte-binding, although most of them do display changes of emission intensity and lifetime. Since the unique characteristic of luminescent iridium(III) complexes is their diverse excited-state nature which gives rise to distinct emission features, the researchers believe that new biological probes derived from these complexes should exhibit variable emissive-state nature and environment-dependent emission profiles and spectral characteristics. In this project, the researchers will design novel luminescent sensors by incorporating biologically important molecules into two classes of dual-emissive iridium(III) polypyridine complexes that they have very recently discovered. The photophysical, photochemical and electrochemical properties and electronic structures of these complexes will be studied. The binding of the complexes to biological receptors including avidin, indole-binding proteins, estrogen receptors, fatty acid-binding proteins and lectins will be examined by various spectroscopic titrations and biological assays. Additionally, the cytotoxicity and cellular uptake properties of the complexes will be investigated using HeLa cells as a model mammalian cell line. Furthermore, the potential use of the complexes as biological imaging reagents will be evaluated.