Photochemistry and Solar Energy Conversion

Development of sustainable, renewable energy sources is one of the most challenging tasks being addressed by chemists today.  Our group is contributing to this field by developing multi-component systems for the photo-reduction of protons from water.  Traditional work in this group and others has focussed on platinum(II) or ruthenium(II)-based chromophores (see J. Am. Chem. Soc. 2007, 129(25), 7726 and J. Am. Chem. Soc. 2008, 130(15) 5056); thus, we are also interested in the study of new Pt(II) chromophores (for example: Inorg. Chem. 2009, 48(4), 1498).  One principal disadvantage of this approach is the cost of precious metals.  Recently, we have discovered the utilization of cobalt dimethylglyoximate complexes as molecular catalysts in conjunction with Pt(II) chromophores (J. Am. Chem. Soc. 2008, 130(38), 12576).  In addition, we are pursuing covalent attachment of the Pt(II) chromophore to the cobalt complexes to form molecular devices.  Finally, we are investigating the use of water-soluble organic dyes as chromophores in combination with the cobalt catalysts.

Other applications of luminescence in metal complexes include the use of these compounds as dopant emitters in Organic Light Emitting Devices (OLEDs) and as potential chemosensors.  Regarding OLED emitters, we are focussing heavily on copper (I)-based systems since copper is an inexpensive, earth-abundant, non-toxic metal.  Unlike tradional Ir(III) luminescent complexes, emissive Cu(I) complexes have not been studied as well even though long-lived excited states and efficent photoluminescence have been observed.  Specifically, we are interested in neutral complexes which are more useful for device fabrication than are charged species.  For sensor application, we are investigating new gold(I) species which display inter- and intramolecular interactions in the solid state which often affect their photoluminescence (see Inorg. Chem. 2008, 47(3), 957).

Catalysis

Our group is interested in the development of  eletrophilic, cationic iridium(III) complexes which are capable of promoting electrocyclizations and tandem reaction sequences such as the Nazarov reaction.  Currently, we are investigating complexes with chiral phosphine ligands in pursuit of enantioselective reactivity.  In addition, we hope to develop new poly-dentate phosphite and amine ligands which will impart enhanced Lewis acidity on the Ir(III) center and increase the reactivity of difficult substrates.  We are also interested in the study of hydrogen addition reactions usint parahydrogen induced polarization (PHIP) (see Inorg. Chem. 2007 46(4) 1196).