Green Chemistry

Solar Electrochemistry: The cover-art produced for a paper published in Green Chemistry that describes the use of
sunlight-driven electrochemical reactions to recycle chemical oxidants. Kevin Moeller is researching this and other electrochemical reactions. Find out more at his group website.

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.

The photosynthetic megacomplex from a cyanobacterium, which scientists have managed to isolate in its complete, functioning form, weighs about 6 million Daltons. Bob Blankenship and Michael Gross collaborated on the research.

The Ponder lab is researching advanced force fields for molecular dynamics simulation of water, ions, organic molecules and biopolymers. Our AMOEBA polarizable model produces "chemically accurate" interaction energetics for many systems and is being used in a variety of applications, including: proteins folding analysis, computation of free energies of binding in host-guest and protein-ligand systems, and prediction of small molecule crystal structures.

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).

This class of asymmetric catalysts developed by the Birman group shows remarkable efficacy and versatility in promoting enantioselective acylation reactions and related transformations. Their ease of preparation and flexibility of the catalyst design contribute to their growing popularity in the synthetic community.

The Hayes and Conradi groups are collaborating on in situ high-pressure high-temperature NMR to monitor the reaction of CO2 as it converts to magnesium carbonate and calcium carbonate.  This work involves WU's Consortium for Clean Coal Utilization

Read more in this special issue of Environmental Science & Technology: Surface et al. Environ. Sci. Technol., 2013, 47, 119?125. DOI: 10.1021/es301287n

The image shows a "site-selective" reductive amination sequence on a microelectrode array, investigated by Kevin Moeller's group. In this experiment, Pd(II) is used at selected electrodes as an oxidant to generate a carbonyl for the reductive amination. Two reactions were conducted placing different fluorescent dyes on the array.

Two Lasers

The Michael Gross group intersects two lasers: the first is a temperature jump at 1900 cm-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).

Native Electrospray Mass Spectrometry Reveals the Nature and Stoichiometry of Pigments in the FMO Photosynthetic Antenna Protein

The FMO antenna protein from green sulfur photosynthetic bacteria has been analyzed by native mass spectrometry by Wen et al. Biochemistry (2011) 50: 3502-3511. This revealed additional pigments that function to couple this complex to the chlorosome complex that feeds energy to it. This work was a collaboration between the Blankenship and Gross research groups.
 

The image shows a "site-selective" Wacker oxidation on a microelectrode array, fabricated(?) by Kevin Moeller's research group. In this experiment, the Wacker oxidation is triggered by using the electrodes in the array to generate a Pd(II) oxidant.

Determining Protein:Ligand Affinities by PLIMSTEX (Protein-Ligand Interactions by Mass Spectrometry, Titration, and H/D EXchange):

Using a new approach in mass spectrometry, the Michael Gross group follows amide exchange of a protein during titration with any ligand to give protein affinities. The curve, after modeling, yields the binding constant (Κi or βi)

Read more. . .

Using a pulsed laser to give h?, the Michael Gross group photolyzes HO-OH to produce HO• for foot printing solvent-accessible side chains on proteins. The approach, coupled with MS analysis, maps protein interfaces faster than a protein can unfold.

Coupling two light absorbing pigments, a perylene and a porphyrin, into a dyad motif results in the unexpected ability to tune electronic structure of the chromophores and allows intense absorption of light spanning near-ultraviolet to near-infrared regions of the solar spectrum while maintaining a long excited-state lifetime and high fluorescence yield.

Three synthetic bacteriochlorins (mauve, gold, teal) are each attached to a native-like bacterial photosynthetic β-peptide (green), which self assembles with α-peptide (blue) and bacteriochlorophyll (purple) to form a dyad (top left) and then a cyclic oligomer with enhanced absorption (lower left).  The three constructs can be combined to give cyclic oligomers (top right) with blended bacteriochlorin absorption (lower right) and ~95% energy-transfer efficiency.

Seminars

Date Event description Operations
Jan
08
Design of polyketide synthases for the engineered production of highly reduced compounds | Ryan Phelan
To Be Determined @ 4:00 pm
Jan
13
Mechanisms Controlling Phosphoinositide Synthesis at the Plasma Membrane | Jememy Baskin
To Be Determined @ 4:00 pm
Jan
29
To Be Announced | Joel Rosenthal, University of Delaware
McMillen 311 @ 4:00 pm

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