Transition Metal CatalysisWith our continue effort on the study of metal-ligand multiple bonds and their application on transition metal catalysis for practical organic transformation, various metal catalysts have been developed for oxo, carbene and nitrene transfer/insertion reactions. Through judicious choice of ligands and metal ions, we are able to synthesize and isolate diverse classes of highly reactive metal-oxygen, -nitrogen and -carbon multiple-bonded complexes for understanding the mechanism of atom and group transfer reactions to organic substrates via at the molecular level spectroscopic measurements and/or by DFT calculations. Useful structural information is obtained for the rational design of more robust metal catalysts with higher selectivity.
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Luminescent Materials & OLED Applications
Platinum(II), gold(I)/(III) and palladium(II) complexes can be developed to have long-lived and emissive electronic excited states for light-induced multi-electron atom transfer reactions and for activation of small molecules of natural abundance. Of particular interests are the observation of metal-solvent/anion exciplex emissions from d10 metal complexes and light-induced inner-sphere H-atom abstraction reactions of platinum(II) and gold(I) complexes. Current research aims to develop highly robust metal complexes having high energy and long-lived electronic excited states for light-to-chemical energy conversion. We intend to use the phosphorescence of transition metal complexes as luminescent probes for molecular recognition reactions and for the detection of bio-molecules with practical interest. We are studying organic triplet emissions that are switched on through metal ion coordination. Applications of phosphorescent and thermally-activated delayed fluorescent metal-organic compounds in organic optoelectronics such as organic light-emitting diodes (OLED) are under active investigation.
Chemical Biology & Anti-Cancer Medicines
The therapeutic applications of gold and platinum complexes have long been known for treatment of major diseases. Through the use of NHC carbene and porphyrin ligands, Au(I), Au(III) and Pt(II) ions can form stable lipophilic cations having tunable lipophilicity and reactivity that display potent anti-cancer effect. The Au(III) porphyrins and pincer type Au(III)/Pt(II) complexes we developed exhibit effective in vivo anti-cancer effects in a variety of mice models of tumor xenografts and metastasis . We introduce drug nano-carriers to formulate anti-cancer gold and platinum complexes and developed complexes with self-assembled nanostructures to enhance the anti-cancer efficacy. We use chemical probes, thermal proteome profiling and nanoscale elemental imaging to elucidate the mechanisms of action and identify the direct biomolecular targets responsible for the anti-cancer effects. We have also extended the application of these chemical formulation and target identification strategies to the research and development of some natural products from commonly used Chinese medicines with an aim to explore relatively nontoxic chemotherapeutic agents.
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