Two Lasers

The Michael Gross group intersects two lasers: the first is a temperature jump at 1900 nm-1(IR) to heat a flowing solution containing a protein and perturb its folding. The second at 248 nm (UV) is an FPOP probe generating OH radicals that footprint the folding state of the protein on the microsec time scale. For a description of this work, see: T-jump and Fast Photochemical Oxidation Probe Sub Millisecond Protein Folding, Jiawei Chen, Don L. Rempel, Michael L. Gross, J. Am. Chem. Soc. 132, 15502–15504 (2010).

A series of NiIII complexes containing aryl and alkyl ligands was shown to reductively eliminate to form new C-C or C-heteroatom bonds. The Mirica Group is investigating these NiIII complexes to better understand the role of NiIII intermediates in Ni-catlayzed coupling reactions.

Bis(hydrocarbyl)NiIII complexes have been commonly proposed in Ni-catalyzed cross-coupling reactions, however no such bis(hydrocarbyl) complexes have been reported to date. Recently, several organometallic NiIII complexes containing two trifluoromethyl ligands were recently synthesized and fully characterized in the Mirica Group.

Azapentadienyl-metal complexes possess two potential sites of reactivity for electrophiles, the nitrogen atom and the basic metal center.  The Bleeke group has investigated the reactions of (1,2,3-η3)-(5-t-butylazapentadienyl)Rh(PMe3)x (x = 2 or 3) and (1,2,3-η3)-(5-t-butylazapentadienyl)Ir(PEt3)x (x = 2 or 3) with triflic acid and has shown that either the nitrogen atom or the metal center can serve as the primary reaction site (see accompanying graphic).

Analysis of metabolic extracts from biological samples with liquid chromatography/mass spectrometry (LC/MS) results in large datasets containing information on thousands of analytes.  It is impractical to analyze the results manually.  There are a number of software solutions available to process untargeted metabolomic data, however, they suffer from problems such as those shown to the left.  The Patti group is developing new algorithms to improve processing of untargeted metabolomic data.

Krishna Sharmah in the Birman group has recently completed a concise enantioselective synthesis of lingzhiol, a meroterpenoid with an unprecedented skeleton isolated from the mushroom Ganoderma lucidum widely used in traditional Chinese medicine under the name ling-zhi. Ligzhiol shows potent and selective inhibition of phosphorylation of Smad3 proteins implicated in renal fibrosis.

 

Using electrochemical techniques, the Mirica Group has recently shown that the tetradentate pyridinophane ligand tBuN4 undergoing conformational changes that are essential for stabilizing PdIII and other uncommon oxidation states of various transition metals.

A series of PdII and PtII complexes supported by a tetradentate ligand having both nitrogen and sulfur donor atoms displays unique d8-d8 interactions between metal centers unsupported by bridging ligands. The Mirica group is probing the role of these interactions in methyl group transfer reactions and other organometallic transformations.

Faculty, doctoral students and undergraduates talk about the department and their experiences at Washington University. From the outset, students get exposed to a broad range of expertise and fields. Interdisciplinary and collaborative research are strengths of this medium-sized department with considerable resources, instrumentation, and facilities.