Probing halogen bonds using novel NMR methods

Faculty of Science
Aerial view of D'iorio building
Over the past two decades, halogen bonding has seen an upsurge of interest by the scientific community.

Halogens participating in halogen bonding include iodine (I), bromine (Br), chlorine (Cl), and sometimes fluorine (F). This kind of bonding is shown to occur in various biological systems and chemical processes. Due to its ubiquity, it can be exploited for a range of functional applications including drug design, crystal engineering, supramolecular chemistry, polymer sciences, liquid crystals, conductive materials and medicinal chemistry. Yijue Xu, a PhD student working with Professor David L. Bryce spent most of her doctoral studies developing novel solid-state nuclear magnetic resonance (NMR) methods to characterize halogen bonds in various cocrystalline compounds, including those comprising diiodoperfluorobenzenes as strong halogen bond donors.

Yijue pioneered early NMR measurements on oxygen-17 labeled halogen-bonded powders, which helped gain insight into the electronic structure of the halogen bond and by extension, the properties of the materials being analyzed. Yijue’s work provides some of the only experimental NMR tensor data available for understanding a range of halogen-bonded systems. These data have provided new insights into these non-covalent chemical interactions and allowed for parallels to be drawn with the ubiquitous hydrogen bonds. Yijue also developed a python-based software package, SCFit, to analyze NMR data acquired on large single crystals. This software is freely available to the research community. Her research helps extend the applications of NMR spectroscopy to study diverse materials comprising halogen bonds.

Recent PhD graduate Yijue Xu and Professor David Bryce
Recent PhD graduate Yijue Xu and Professor David Bryce

Over the course of her PhD, Yijue has co-authored 11 peer-reviewed publications and delivered 14 conference presentations. She also received the Ontario Graduate Scholarship for international students alongside numerous awards, including a first prize for the best poster at the Groupement Ampere International NMR School. Yijue’s publications have been highlighted many times on journal covers, including the American Chemical Society’s Journal of Physical Chemistry. Her paper entitled “A Rare Example of a Phosphine as a Halogen Bond Acceptor”, published by the Royal Society of Chemistry’s Chemical Communications, was highlighted in a news article published by ChemistryViews.

Yijue was recently awarded a postdoctoral fellowship at the National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida. She attributes her success to the support and mentorship of Prof. Bryce and the invaluable technical support that she received from the NMR manager, Dr. Glenn Facey, and X-ray manager, Dr. Bulat Gabidullin.