It’s finally here. At long last, the 800 MHz NMR magnet rolled up behind Bagley Hall last week on a very big truck in a very big box (see pictures below). The move of a 3-ton object from Europe to the basement of Bagley was only achieved after considerable planning and with the help of many experts. Among other things, the planning included assuring ourselves that the magnet in transit from the loading dock to its new home would not choose to travel suddenly from the ground floor to the sub-basement (meaning, cause the collapse of the suspended concrete slab that serves as the floor). Disaster did not ensue: the magnet is now in its new home, resting on a concrete slab directly in contact with mother Earth. Stay tuned as the super-conducting coils are cooled within a few degrees of absolute zero and are brought to the electrical current needed to achieve an 18.8 Tesla magnetic field. Congratulations and thanks to Professors Drobny, Klevit, and Varani for winning the grant that purchased this new instrument that will benefit so many research projects. And mega-kudos to Chemistry’s Director of Technical Services, James Gladden, who has so capably led the Department’s planning efforts for this installation.
According to a recent report, the University of Washington led the world in impact of publications in materials science research during the period 2001-2011. This analysis, by Thomson-Reuters, focused on 800 papers published at the UW in the field of materials science, which were collectively cited about 24,000 times, achieving a remarkable 30.41 citations per publication. The UW’s performance was closely followed by a number of outstanding private and public institutions. Chemistry Chair Paul Hopkins points out that even in a large university such as the UW, the work of a small number of faculty members can strongly influence the outcome of such analyses. He points out that UW Chemistry Professor Daniel Gamelin, UW Chemistry and Materials Science Professor Alex Jen, UW Chemistry and Chemical Engineering Professor Samson Jenekhe, and former UW Chemistry Professor Younan Xia together published a total of nearly 750 papers in that time period that were cited over 43,000 times, or 58 citations per paper. Though all of these papers were clearly not included in the Thomson-Reuters analysis, Hopkins believes that that the work of chemists Gamelin, Jen, Jenekhe, and Xia was critical to lifting the UW to the number one spot. Hopkins hopes that prospective graduate students and postdoctoral associates in this field will take notice of the UW’s outstanding performance and strongly consider joining this exciting program at the UW.
Professor Alex Jen, Boeing-Johnson Chair professor of materials science and engineering and professor of chemistry, and his co-workers have demonstrated the ability to foster an extremely unlikely chemical reaction between two molecules by tethering them into the correct orientation on a gold surface. The study is reported in the March 11, 2011 issue of Science. The research was also highlighted in the March 14, 2011 issue of Chemical & Engineering News:
“In the work, chemists led by Paul S. Weiss and Kendall N. Houk of the University of California, Los Angeles, and Alex K-Y. Jen of the University of Washington, Seattle, tied two anthracene analogs next to each other on a gold surface. This forced the molecules to react in a manner that, although theoretically possible in solution, rarely occurs there because of unfavorable geometry.
“In principle, the mallet-shaped molecule 9-phenylethynylanthracene (PEA) should undergo a 4 + 4 photocycloaddition with another molecule of PEA. But because of geometric constraints, that reaction rarely happens. Instead, one PEA’s anthracene moiety tends to do Diels-Alder chemistry with the ethynyl unit on another PEA’s phenylethynyl handle.
“To force the disfavored reaction, the researchers attach a thiol group to the end of PEA’s handle and tether two such molecules next to one another on a gold surface within the defect sites of a self-assembled alkanethiolate monolayer. The anthracene moieties are then poised in the correct orientation to do the photocycloaddition when photoexcited.”
To learn more about Prof. Jen’s research, visit his group research page.
For more information about the Science article, read the UW press release.
Dr. Stefan Ochsenbein, a postdoc working with Prof. Daniel Gamelin, Harry and Catherine Jaynne Boand Endowed Professor of Chemistry, is lead author on a new paper published in Nature Nanotechnology reporting the first successful coherent impurity spin manipulation within colloidal semiconductor nanocrystals (also known as quantum dots). Spin effects in semiconductor nanostructures have attracted broad interest for potential spin-based information processing technologies, whether in spin-electronics (“spintronics”) or spin-photonics. Colloidal doped semiconductor nanocrystals present interesting possibilities for constructing devices by solution processing or that involve integration with soft materials (e.g., organics), but their spin properties remain relatively untested. For example, the possibility to manipulate spins within colloidal semiconductor nanocrystals coherently, as would be necessary for many proposed applications, had not been demonstrated until these latest experiments.
In this paper, Ochsenbein and Gamelin describe the first observation of coherent spin manipulation in colloidal doped quantum dots. The observation was made by demonstrating microwave-driven Rabi oscillations within the high-spin ground states of Mn2+ impurity ions doped into colloidal ZnO semiconductor nanocrystals. Their electron spin-echo measurements revealed long spin coherence times approaching 1 µs, sufficient for potential qubit applications with optical excitation. The authors also identified previously unobserved hyperfine interactions between Mn2+ electron spins within the quantum dots and proton nuclear spins outside the quantum dots, revealing an important but previously unrecognized contribution to spin decoherence in such quantum dots.
Read the article: “Quantum oscillations in magnetically doped colloidal nanocrystals.” Ochsenbein, S. T.; Gamelin, D. R., Nature Nanotechnology, 2011, 6, 112–115.
The research of Prof. Larry Dalton, B. Seymour Rabinovitch Endowed Chair in Chemistry, was recently featured as part of C&E News’ cover story highlighting the key research advances in chemistry over the last decade. The article describes the advances the Dalton research group has made in designing devices that convert electrical data into optical information at high rates of speed (more than 110 gigahertz) under low drive voltages (less than 1 V). These types of devices have a wide variety of uses in fiber-optic and satellite communication systems and for optical-switching technology.
Pradipsinh K. Rathod, Professor of Chemistry, was awarded a $ 1,000,000 grant from the Bill & Melinda Gates Foundation as part of the next phase of Grand Challenges Explorations, an initiative to encourage bold and unconventional ideas for global health. The grant will provide continued support for Prof. Rathod’s global health research project “Strategies to Disable Hypermutagenesis in Malaria Parasites.”
Prof. Rathod proposed that drug resistance in malaria parasite populations is driven by cellular components, a “mutasome”, that promotes acquisition of multiple mutations at target loci in the genome. All malaria parasites may have had an ancestral, pre-existing mechanism to mutate surface proteins at extraordinary rates to avoid host immunity. However, parasite populations displaying the Accelerated Resistance to Multiple Drugs (ARMD) phenotype may have hijacked such a machinery to now make changes anywhere in the genome. Genomic studies are geared to identify genome components which help drive hypermutagenesis, and high throughput screens are being developed to directly block the process with small organic molecules. An ability to chemically disable such a mutasome during malaria therapy would improve success rates and staying power of new antimalarial drugs. Laboratory Post-Doctoral colleagues John White and Jenny Guler, and graduate student Joseph Fowble conduct experimental design and implementation on the GCE project in the Rathod laboratory.
Grand Challenges Explorations is a five-year, $100 million initiative of the Gates Foundation to promote innovation in global health. For more information, visit http://www.grandchallenges.org/explorations.
To learn more about Prof. Rathod’s research, visit his faculty page.
Pictured: Prof. Rathod and Dr. Jennifer Guler in the lab (photo by Mary Levin).
Stephanie Benight, a 5th year graduate student working with Larry Dalton and Bruce Robinson, is lead author on a paper recently featured as the cover story in the Journal of Physical Chemistry B (Sept. 23rd issue). Benight’s graduate research has been focused on investigating intermolecular interactions in electro-optic chromophore systems using experimental and theoretical methods. Organic electro-optic (EO) materials have the potential to minimize the size, weight, and power requirements of next generation computing, telecommunications, and sensing applications.
In this article, Benight and coworkers demonstrate both experimentally and theoretically that lattice dimensionality can be defined using the relationship between centrosymmetric order and acentric order. Experimentally: Acentric order of a chromophore system is determined by attenuated total reflection measurement of electro-optic activity coupled with hyper-Rayleigh scattering measurement of molecular first hyperpolarizability, and centrosymmetric order is determined by the variable angle polarization referenced absorption spectroscopy method. Theoretically: Order is determined from statistical mechanical models that predict the properties of soft condensed matter.
Full citation: [Stephanie J. Benight, Lewis E. Johnson, Robin Barnes, Benjamin C. Olbricht, Denise H. Bale, Philip J. Reid, Bruce E. Eichinger, Larry R. Dalton, Philip A. Sullivan, and Bruce H. Robinson, J. Phys. Chem. B, 2010, 114 (37), pp 11949–11956.]
Pictured: Stephanie Benight and a few of the co-authors of the paper. (Left to right) Lewis Johnson, Prof. Bruce Robinson, and Stephanie Benight.
UW Chemistry professors Michael Gelb and Forrest Michael, in collaboration with Prof. David Baker (UW Biochemistry), have engineered an artificial enzyme capable of catalyzing a bimolecular Diels-Alder reaction with high stereoselectivity and substrate specificity. Their findings were reported July 16 in Science. The team of collaborators used computer modeling to screen over 10 billion possible protein backbone geometries for the ones that could support the right combination of active sites and catalytic residues. From this list, and further optimization, 84 de novo designs were selected for experimental work. Ultimately, two of the designed enzymes showed the ability to catalyze the Diels-Alder reaction.
The Diels-Alder reaction is one of the cornerstones of synthetic chemistry and no naturally occurring enzymes have been shown to catalyze it. Broader application of de novo enzyme design should be significantly useful in synthetic chemistry.
The authors of the paper also include Justin Siegel (graduate student in biochemistry, UW), Alexandre Zanghellini (graduate student in biochemistry, UW), Helena Lovick (graduate student in chemistry, UW), Gert Kiss (graduate student in chemistry, UCLA), Abigail Lambert (former graduate student with Prof. Stoddard), Jennifer St. Clair (Dept. of Biochemistry, UW), Jasmine Gallaher (lab technician, Baker lab), Barry Stoddard (Professor at Fred Hutchinson Cancer Research Center in Seattle), Don Hilvert (Professor of Chemistry, ETH Zurich), Michael Gelb (Professor of Chemistry, UW), Ken Houk (Professor of Chemistry, UCLA), Forrest Michael (Associate Professor of Chemistry, UW), David Baker (Professor of Biochemistry, UW).
Picture: UW graduate student Justin Siegel, professor Forrest Michael, professor Michael Gelb and post-doctoral fellow Alexandre Zanghellini (Steve Ringman / The Seattle Times).
J. B. Siegel, A. Zanghellini, H. M. Lovick, G. Kiss, A. R. Lambert, J. L. St. Clair, J. L. Gallaher, D. Hilvert, M. H. Gelb, B. L. Stoddard, K. N. Houk, F. E. Michael, D. Baker “Computational Design of an Enzyme Catalyst for a Stereoselective Bimolecular Diels-Alder Reaction”, Science, 2010, 239, 309-313
Read the article in The Seattle Times
Read the Chemistry World article
Two recent journals have highlighted the research of the UW-based Science and Technology Center on Materials and Devices for Information Technology Research (CMDITR). The October 28, 2009 issues of the Journal of Materials Chemistry was a themed issue centered on Nonlinear Optics and featured articles by several CMDITR researchers as well as a cover photo highlighting that research. Even more recently, the January 19, 2010 issue of Accounts of Chemical Research also featured cover art depicting CMDITR research – primarily related to the article “Theory-Inspired Development of Organic Electro-optic Materials” by UW researchers Philip A. Sullivan and Larry R. Dalton.
Read the articles:
Accounts of Chemical Research: DOI: 10.1021/ar800264w
Journal of Materials Chemistry, 28 October, 2009
Visit the CMDITR website at www.stc-mditr.org
Professor Karen Goldberg and researchers at the University of North Carolina and the University of Washington have described the first observation of a metal complex that binds methane in solution. The finding is reported in the October 23, 2009 issue of Science. The Science report describes a σ-methane complex that is shown to be quite stable in solution. This report is the first observation and full characterization of a relatively long-lived σ-methane complex in solution. Nuclear magnetic resonance (NMR) spectra of the complex were obtained by protonation of a rhodium-methyl precursor at -110 °C. The complex is observed to rapidly tumble in the coordination sphere of rhodium, exchanging free and bound hydrogens. Density functional theory calculations indicate that the complex is best described as η2-C,H methane coordination to the metal.
Professor Goldberg is the Director of the UW-based NSF Center for Enabling New Technologies through Catalysis, a Center for Chemical Innovation that seeks to find efficient, inexpensive and environmentally friendly ways to produce chemicals and fuels.
Citation: “Characterization of a Rhodium(I) σ-Methane Complex in Solution” Wesley Bernskoetter, Cynthia Schauer, Karen Goldberg, Maurice Brookhart, Science, 326 (5952), 553 (23 October 2009)
Read the Science paper