Fall/Winter 2022 Alumni Magazine

A New Venture for the Crystallography CORE

Expanding the X-Ray Lab

By Josh Chen

The Department of Chemistry X-ray Crystallography Core Laboratory at UNC Chapel Hill (XCL) serves to support research effort within and outside the University with both single crystal- and powder X-ray diffraction (SC-XRD and PXRD) techniques. XCL has recently acquired a new Bruker D8 VENTURE single crystal X-ray diffractometer, a much-needed upgrade from the decade-old diffraction systems in the laboratory. The newly acquired D8 VENTURE contains a molybdenum microfocus source and a highintensity copper/diamond source, suitable for inorganic, organic, and macromolecular crystalline samples. The copper/diamond is currently the strongest in-house X-ray radiation source available in North Carolina and is specially designed to collect data on protein crystals and microcrystals (< 5 μm) that often diffract poorly using seal-tube X-ray sources. Together with Oxford Cryostream 800 Plus with operational temperature between 80-500 Kelvin, the instrument is capable of conducting temperature-induced phase transition study on a wide range of materials.

Pictured: The D8 VENTURE

X-ray crystallography is one of the most powerful analytical techniques in structure determination on solid state materials. It provides direct and detailed structural information, including absolute configuration of chiral compounds and studies on intermolecular interactions, which are challenging using other analytical methods. Recognized for its reliability in structure confirmation with little ambiguity, X-ray crystallography is often required for publications.

Despite it's tremendous value, X-ray crystallography isn’t without drawbacks. For example, the sample must be crystalline. Many reaction products do not crystallize easily, resulting in small and poor-quality crystals that do not produce diffraction strong enough for structure elucidation with standard sealed-tube X-ray source and a CCD detector. Moreover, X-ray data analysis usually takes longer than other conventional methods such as nuclear magnetic resonance (NMR) and Mass Spectrometry. A standard 4- to 8- hour data collection per sample is not feasible for X-ray crystallography to be implemented in undergraduate laboratory courses. In the past, most of the students could only experience X-ray crystallography through their graduate research.

The new D8 VENTURE and its high-brilliance sources with a large, highly sensitive PHOTON III detector significantly shortens the data collection time (60 x the speed and efficiency comparing to the last-gen X-ray diffractometer), enabling structure solution in minutes! This opens up an avenue for X-ray crystallography to be implemented in our undergraduate curricula, allowing undergraduate students to be exposed to this wonderful analytical method.