Ultrafast Population and Structural Dynamics of a Ni-Bipyridine Photoredox Catalyst Reveal a Significant Deactivation Pathway
Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide The ultrafast excited state pathways and dynamics of Ni II -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 II -bipyridine aryl halide complex, [Ni( t -Bu bpy)( o -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 II -bipyridine aryl halide cross-coupling catalysts.
Authors: Sumana L. Raj, Felipe Curtolo, Kacie J. Nelson, David A. Cagan, Reagan X. Hooper, Daniel Bím, Alec H. Follmer, Ryan D. Ribson, Nathanael P. Kazmierczak, Brendon J. McNicholas, Natalia Powers-Riggs, Michael Sachs, Elisa Biasin, Dimosthenis Sokaras, Jinkyu Lim, Leland B. Gee, Matthieu Chollet, Patrick Kramer, Roberto Alonso Mori, Tim B. van Driel, Kelly J. Gaffney, Sijia S. Dong, Ryan G. Hadt, Amy A. Cordones
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funders: National Science Foundation, U.S. Department of Energy, Hertz Foundation, European Commission, National Institutes of Health, Office of Science, National Institute of General Medical Sciences, Basic Energy Sciences, SLAC National Accelerator Laboratory, HORIZON EUROPE Marie Sklodowska-Curie Actions, National Science Foundation Graduate Research Fellowship Program, Ford Foundation Fellowships
Awards: G1141120041, G1229526393, G1286251239, G2371548206, G2379306141, G2522871517, G262532246, G4235786860, G4654690619, G495301720, G498139845, G500318789, G5570207115, BIOINSPIRED LIGHT-ESCALATED CHEMISTRY (BIOLEC), G6550344761, Graduate Research Fellowship Program (GRFP), G7283024673, BIOINSPIRED LIGHT-ESCALATED CHEMISTRY (BIOLEC), G8081606212, G8382000481, Understanding Geometric and Electronic Structure Contributions to Ground and Excited State Cu- and Ni-Catalyzed Cross-Coupling Reactions, G911061179, G969889393
OpenAlex ID: W7124882245