This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
With this award from the Major Research Instrumentation (MRI) program Professor Zerihun Assefa and colleague Debasish Kuila from the Department of Chemistry at North Carolina Agricultural & Technical State University will acquire an automated bench-top single crystal X-ray diffractometer. The instrument will also be used by researchers at the University of North Carolina at Greensboro and will support research activities such as: 1) study of disruption of metal-metal interactions and extended linear chains by organic solvent molecules; 2) synthesis, X-ray crystallography, and photoluminescence studies of high-coordinate gold(I) complexes with tertiary phosphine ligands; 3) use of light harvesting ligands to enhance emission from metal sites; and 4) study of small prototype molecules of biological, bioorganic, and bioinorganic interest.
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 chemistry, materials chemistry and biochemistry. This instrument will be an integral part of teaching as well as research at this historically black university.
": PI: Zerihun Assefa, Co-PI—Debasish Kuila, Chemistry Department, North Carolina A&T State University, Greensboro, NC Many thanks to NSF, the MRI grant has allowed us to purchase a single crystal X2S X-ray diffractometer that enhanced the material research and education in STEM area at North Carolina A & T State University. The university typically serves a large percentage of underrepresented minority students. The arrival of the instrument has increased the research output, foster collaborative effort, and enhanced training of largely minority graduate and undergraduate students. At the initial stage of the installation 12-graduate students and faculty were trained in the art of single crystal growth and structural elucidation. During the course of the grant, two-PhD students (Darkus Jenkins, and Matthew Mickens) and four-MS students (Shaka Gore, Kendra Whitehead, Carlos Crawford, and Derick Forcha) have graduated with their thesis work partly performed on this X2S X-ray diffractometer instrument. All six are minority students. Several more students are at various levels of training currently. The work performed on this instrument has allowed submission of 5-manuscripts so far with many more to come. In addition, the availability of the instrument has allowed course development and training of students in diffractometeric techniques and single crystal growth procedures. A new graduate level course (CHEM 641) has been developed and approved by the university’s curriculum committees for implementation starting Spring 2014 semester. Undergraduate seniors will also be allowed to attend the course. The imapact of this instrument in performing high level research is tremendous. Significant progress has been achieved involving development of methodologies that may increase the efficiency of emission intensity observed from lanthanide species. Students are actively synthesizing several new designer compounds and elucidate their structural features using the X2S diffractometer. For example, a gold phosphine compound which could further be studied for chemo preventive action has been synthesized recently in a mononuclear fashion. In addition the crystal structure of the dinuclear gold (I) system with two benziimdazole ligands coordinated through the phosphorus and nitrogen atoms has also been crysatllized and its structural feature analyzed. The compound features an eight-membered ring system consisting of two metals, two phosphorus, two nitrogen, and two carbons. Atoms in the ring system are arranged in a head-to-tail and tail-to-head, P-Au-N and N-Au-P manner. Moreover, an organic solvent, acetonitrile, is seen trapped uncoordinated within the crystal. The gold-gold distance is very short and is only 2.8 Å. This compound is currently being tested for its ability to function as a sensor for acetonitrile, which is a marker for forest fire activities The silver analog of the compound has a longer Ag-Ag distance of 3.01 Å in addition to containing two acetonitrile bound to the Ag center. The ability to elucidate structural features of several new compounds has enhanced the research activities and students’ interest to engage in STEM based research.
