New Hub Aims for Clear-Cut Edge in Crystallography Research

The University of Texas at Dallas has added faculty experts and new equipment to help establish a national crystallography hub for advanced chemistry and materials science research.

Dr. Mario Wriedt, associate professor of chemistry and biochemistry and Fellow, Francis S. and Maurine G. Johnson Chair, joined the UT Dallas faculty in 2023 to direct the Crystallography Center and its X-ray Diffraction Facility in the School of Natural Sciences and Mathematics.

Crystallographers use techniques such as X-ray diffraction to study the detailed 3D atomic structure of materials. In single-crystal X-ray diffraction, X-ray beams are directed toward a single crystal of a material. Detectors record how the X-rays diffract, or interact with the atoms in the sample, providing researchers with information about the crystal's structure.

The data that are generated help scientists understand better the mechanisms behind chemical reactions and inform the design of new materials with a wide range of uses, from medicine to energy storage to environmental cleanup.

During the past year, UTD's Crystallography Center has been renovated, and a Bruker D8 Venture Single Crystal X-ray Diffractometer, which features a Microfocus Diamond II X-ray source and Photon III detector, has been added to the lab's existing instrumentation.

"This new instrument generates ultra-high intensity, very bright X-rays and allows us to do challenging experiments in-house," Wriedt said.

The intensity of the X-rays generated by the Bruker diffractometer rivals that generated by a synchrotron, a device that generates X-rays with a particle accelerator.

"We previously had to send samples of very small crystals to synchrotron facilities, but now we can not only collect these data at UTD but also in record time," Wriedt said.

The new equipment also boosts the capability of analyzing the crystal structure of nanoporous metal-organic frameworks, or MOFs. These materials, which resemble jungle gym-like structures, are an important area of study due to their high degree of structural tunability combined with ultra-high surface areas, making them promising candidates for unique applications.

"We previously had to send samples of very small crystals to synchrotron facilities, but now we can not only collect these data at UTD but also in record time."

Dr. Mario Wriedt, associate professor of chemistry and biochemistry and Fellow, Francis S. and Maurine G. Johnson Chair

For example, Wriedt is a leading researcher in the development of MOFs for water remediation, such as the removal of a group of chemicals known as PFAS, or perfluoroalkyl and polyfluoroalkyl substances, often described as forever chemicals, from contaminated sources.

"MOF crystals are generally difficult to characterize by X-ray diffraction because their lattices contain a lot of empty space," Wriedt said. "These voids are usually filled with solvent molecules, which are not ordered as in the crystal. This limits the diffraction quality of the overall crystal. With our new, much brighter X-ray source and advanced detector technology, we can overcome this challenge."

Although its primary focus is characterizing small molecules, the crystallography facility also adds support for researchers who study macromolecular structures such as proteins.

"Protein crystallography is an entirely different field," Wriedt said. "It used to be that you had to send your protein crystals exclusively to synchrotron facilities. Now, using this bright X-ray source, we will be able to screen and test protein crystals in-house. This significantly reduces time and resources since only selected crystals will be sent to synchrotrons for data collection."

Offering Advanced Training

While advances in X-ray diffraction technology have made data collection and analysis of crystal structures faster, more automated and more efficient, it still takes a trained eye to spot and process nonroutine, challenging results.

"Advanced tech is now widely available so that any trained student can run data collection and get a crystal structure by clicking on a few buttons in the software package," Wriedt said. "But this is a big problem. While it might work well for routine cases, many errors can occur that require refinement and validation of the structure that an inexperienced user won't see. Such a user might think they have a perfect structure and then publish that data, when in actuality, they've published a poor or wrong structure."

In August, Wriedt partnered with Dr. Peter Mueller, director of the X-ray Diffraction Facility at the Massachusetts Institute of Technology, to host a weeklong workshop at UT Dallas for students, postdoctoral researchers and faculty. About 30 participants attended lectures and gained hands-on experience processing common problems in crystal structure refinement and analysis.

"UT Dallas is building a hub for crystallography research in Texas and the nation, and as part of our mission of excellence in research, service and education, it is vital that we continue to provide such essential professional training in this field," Wriedt said.

The workshop was sponsored by UT Dallas, Bruker Corp. and MiTeGen.