Intra- and Intermolecular Charge-Transfer Dynamics of Carbene-Metal-Amide Photosensitizers.

Autor: Kellogg MS; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Mencke AR; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Muniz CN; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Nattikallungal TA; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Cardoso-Delgado F; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Baluyot-Reyes N; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Sewell M; Department of Chemistry, University of California, Riverside, California 92521, United States., Bird MJ; Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States., Bradforth SE; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Thompson ME; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Jazyk: angličtina
Zdroj: The journal of physical chemistry. C, Nanomaterials and interfaces [J Phys Chem C Nanomater Interfaces] 2024 Apr 12; Vol. 128 (16), pp. 6621-6635. Date of Electronic Publication: 2024 Apr 12 (Print Publication: 2024).
DOI: 10.1021/acs.jpcc.4c01994
Abstrakt: A series of steady-state and time-resolved spectroscopies were performed on a set of eight carbene-metal-amide (cMa) complexes, where M = Cu and Au, that have been used as photosensitizers for photosensitized electrocatalytic reactions. Using ps-to-ns and ns-to-ms transient absorption spectroscopies (psTA and nsTA, respectively), the excited-state kinetics from light absorption, intersystem crossing (ISC), and eventually intermolecular charge transfer were thoroughly characterized. Using time-correlated single photon counting (TCSPC) and psTA with a thermally activated delayed fluorescence (TADF) model, the variation in intersystem crossing (ISC), ( S 1 → T 1 ) rates (∼3-120 × 10 9 s -1 ), and Δ E ST values (73-115 meV) for these compounds were fully characterized, reflecting systematic changes to the carbene, carbazole, and metal. The psTA additionally revealed an early time relaxation (rate ∼0.2-0.8 × 10 12 s -1 ) attributed to solvent relaxation and vibrational cooling. The nsTA experiments for a gold-based cMa complex demonstrated efficient intermolecular charge transfer from the excited cMa to an electron acceptor. Pulse radiolysis and bulk electrolysis experiments allowed us to identify the character of the transient excited states as ligand-ligand charge transfer as well as the spectroscopic signature of oxidized and reduced forms of the cMa photosensitizer.
Competing Interests: The authors declare no competing financial interest.
(© 2024 The Authors. Published by American Chemical Society.)
Databáze: MEDLINE
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