MBI Colloquium

Wednesday, 02. April 2025 // 14.00 -

Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy

Max-Born-Straße 2a, 12489 Berlin
Max Born Hall

Orbital control of catalysis enabled by ultrafast X-rays

Philippe Wernet

Department of Physics and Astronomy, Uppsala University

Conceptually attractive but practically very hard, bond activation in small inert molecules for functionalization and transformation into valuable chemical products is notoriously difficult because the bonds in inert molecules are so stable. Understanding bond activation also poses seemingly insurmountable challenges to experiment and theory. How can we selectively pick, for observation in both space and time, the one functional group that gets activated? How can we accurately describe what it is that activates the bond down to what matters, which is the level of orbital interactions? And how can we still generate testable hypotheses and experimental observables?

The aim of this talk is to demonstrate how ultrafast X-ray spectroscopy can help (1-3). On the example of photochemical C-H bond activation with transition-metal complexes, we will show how the selectivity of X-ray spectroscopy to a given element and chemical site helps in looking at the one bond that gets activated (4, 5). With an optical pulse we trigger the activation reaction and by measuring in a time-resolved mode, we follow how that bond transforms as it is modulated at the active metal site. The sensitivity to specific orbital interactions by comparison to calculated spectra enables us to quantify the chemical interactions that activate the bond. Understanding bond activation at the orbital level, we hope, helps in the design of new catalysts for these reactions. Based on our recent studies, we will reflect on why and how X-ray spectroscopy can be transformative for the investigation of chemical and bio-inorganic processes, how optical and X-ray spectroscopy can be combined to reveal new insight (6) and what future directions might be worth pursuing to be able to better control catalysis at the level of orbitals.

References

(1) Ph. Wernet, Phil. Trans. R. Soc. A 377, 20170464 (2019), http://dx.doi.org/10.1098/rsta.2017.0464
(2) U. Bergmann, J. Kern, R. W. Schoenlein, Ph. Wernet, V. K. Yachandra, J. Yano, Nature Reviews Physics 3, 264 (2021), https://doi.org/10.1038/s42254-021-00289-3
(3) R. M. Jay, K. Kunnus, Ph. Wernet, K. J. Gaffney, Annu. Rev. Phys. Chem. 73, 187 (2022), https://doi.org/10.1146/annurev-physchem-082820-020236
(4) R. M. Jay, A. Banerjee, et al., Science 380, 955 (2023), https://doi.org/10.1126/science.adf8042
(5) A. Banerjee, R. M. Jay, et al., Chemical Science 15, 2398 (2024), https://doi.org/10.1039/d3sc04388f
(6) R. M. Jay et al., J. Am. Chem. Soc. 146, 14000-14011 (2024), https://doi.org/10.1021/jacs.4c02077