With this award from the Chemistry Research Instrumentation and Facilities: Multi-user (CRIF:MU) program, Professor Charles McKenna and colleagues from the University of Southern California will acquire a state-of-the art single-source X-ray diffractometer. The award will enhance research training and education at all levels, especially in areas of study such as (a) environmentally benign energetic materials, (b) C-H activation with palladium complexes, (c) structural analysis of biologically active phosphonates (d) structural studies of fluoroorganic compounds, (e) phosphorescent complexes for optoelectronics, and (f) metal-catalyzed reactions for oxidation catalysis.
An X-ray diffractometer allows accurate and precise measurements of the full three dimensional structure of a molecule, including bond distances and angles, and provides accurate information about the spatial arrangement of a molecule relative to neighboring molecules. The studies described here will impact a number of areas, including organic and inorganic chemistry, materials chemistry and biochemistry. This instrument will be an integral part of teaching as well as research and will also be available to Primarily Undergraduate Institutions in the greater Los Angeles Area for undergraduate research projects.
acquired a Bruker APEX DUO dual-source X-ray diffractometer. This instrument is equipped with a 3 kW sealed tube Mo X-ray source, a high-intensity TRIUMPH Mo monochromator, a 30 W ImS micro-focus Cu X-ray source, an APEX II CCD area detector, and an Oxford Cryostream 700 Series low-temperature device with auto refill. A SHELXTL software site license, licenses for the XD2006 and MAX3D software packages, as well as the Cambridge Crystallographic and the Inorganic Crystal Structure Databases were also purchased. The new diffractometer system replaced a less-reliable and dated Bruker APEX instrument at the USC Center of Excellence for Molecular Characterization. The diffractometer system was delivered to the University of Southern California at the end of February 2011 and was installed in the X-ray crystallographic facility during the first week of March 2011. Immediately after its installation, the system was used to collect diffraction data and determine crystal structures for the members of the Chemistry Department. Since the installation of the new diffractometer, X-ray diffraction datasets have been collected for about 450 samples. Among these were several light atom samples for which an absolute structure determination was not possible with our old Mo/Ka diffractometer. It was possible to determine the absolute structure for these samples with the new dual-source instrument employing Cu/Ka radiation. Structure determinations with this new instrument generally result in much higher data quality. In addition, the data collection times have been significantly shortened compared to the old instrument, resulting in an improved sample throughput of the crystallographic facility. This resulted in a total of 27 published publications in major peer-reviewed journals during the life of this award. In addition, at least 15 more manuscripts have been submitted or are currently being prepared. The X-ray crystallographic facility is overseen by Prof. Ralf Haiges who offers a co-curricular course for research students in which they learn to acquire and process small molecule X-ray diffraction data. A total of 12 faculties, 8 postdocs and 27 students have been using the diffractometer. The diffractometer is also utilized in a four credit undergraduate level course "CHEM488: Introduction to Theory and Practice of X-ray Crystallography" that is taught by Prof. Ralf Haiges. As an integral part of this course, students perform an entire crystal structure determination including crystal selection, data collection, and structure solution. Currently, this course is taught once a year during the fall semester. For the years 2011-2013, the total enrollment was 40 students for the course. While many of the single-crystal samples characterized at the X-ray crystallographic facility at USC are submitted by members of the Department, the X-ray diffractometer as well as the expertise and software of the facility are available to other departments of the university as well as local, national, and international collaborators of academia and industry. The open-access policy and a sample submission form can be found on the website of the facility (http://crystallography.usc.edu).
