Ultrafast Population and Structural Dynamics of a Ni-Bipyridine Photoredox Catalyst Reveal a Significant Deactivation Pathway
The ultrafast excited state pathways and dynamics of Ni<sup>II</sup>-bipyridine complexes influence the yield of photochemical processes involved in their catalytic cross-coupling reactions. Here we present ultrafast Ni Kβ X-ray emission spectroscopy (XES) and X-ray solution scattering (XSS) of a Ni<sup>II</sup>-bipyridine aryl halide complex, [Ni(<sup><i>t</i>-Bu</sup>bpy)(<i>o</i>-tol)Br], to quantify the excited state population dynamics and structural changes of the precatalyst. Due to the local spin-sensitivity of XES, the population dynamics of metal-to-ligand charge transfer (MLCT) and metal-centered (MC) excited states is established. A rapid ground state recovery pathway is newly identified, representing a significant deactivation pathway during photocatalysis. Furthermore, the pseudotetrahedral structure of the long-lived MC excited state is unambiguously identified and refined by XSS. The results advance our understanding of the ultrafast relaxation mechanisms that impact the photocatalytic mechanism and yield for Ni<sup>II</sup>-bipyridine aryl halide cross-coupling catalysts.
Authors
- Matthieu Chollet (ORCID: https://orcid.org/0000-0002-9629-890X)
- Leland Bruce Gee (ORCID: https://orcid.org/0000-0002-5817-3997)
- Reagan X. Hooper (ORCID: https://orcid.org/0000-0001-6835-2860)
- Daniel Bím (ORCID: https://orcid.org/0000-0003-3100-4293)
- Brendon J. McNicholas (ORCID: https://orcid.org/0000-0002-3654-681X)
- Amy. Cordones
- Elisa Biasin (ORCID: https://orcid.org/0000-0002-7276-4224)
- Kelly J. Gaffney (ORCID: https://orcid.org/0000-0002-0525-6465)
- Patrick L. Kramer (ORCID: https://orcid.org/0000-0001-8589-1540)
- Felipe Curtolo (ORCID: https://orcid.org/0000-0002-4459-0968)
- Nathanael P. Kazmierczak (ORCID: https://orcid.org/0000-0002-7822-6769)
- Sijia S. Dong (ORCID: https://orcid.org/0000-0001-8182-6522)
- Michael Sachs (ORCID: https://orcid.org/0000-0001-9775-9336)
- Alec H. Follmer (ORCID: https://orcid.org/0000-0002-6244-6804)
- Dimosthenis Sokaras (ORCID: https://orcid.org/0000-0001-8117-1933)
- Ryan G. Hadt (ORCID: https://orcid.org/0000-0001-6026-1358)
- Natalia E. Powers‐Riggs (ORCID: https://orcid.org/0000-0002-9309-9622)
- David A. Cagan (ORCID: https://orcid.org/0000-0002-4719-2789)
- Ryan D. Ribson (ORCID: https://orcid.org/0000-0002-3755-5777)
- Sumana L. Raj (ORCID: https://orcid.org/0000-0001-5570-3350)
- Kacie J. Nelson
- Tim B. van Driel
- Roberto Alonso Mori
- Jinkyu Lim
Institutions
- California Institute of Technology (US)
- Pacific Northwest National Laboratory (US)
- SLAC National Accelerator Laboratory (US)
- Division of Chemistry (US)
- Linac Coherent Light Source (US)
- Universidad del Noreste (MX)
- Stanford University (US)
Publication Details
- Journal
- The Journal of Physical Chemistry Letters
- Published
- 2026-01-20
- DOI
- https://doi.org/10.1021/acs.jpclett.5c03264
- Primary Topic
- CO2 Reduction Techniques and Catalysts
- Type
- article
- Field-Weighted Citation Impact
- 0.00