2019-11-13
Picosecond to millisecond tracking of a photocatalytic decarboxylation reaction provides direct mechanistic insights
Publication
Publication
Nat. Commun. , Volume 10 - Issue 1 p. 5152: 1- 7
The photochemical decarboxylation of carboxylic acids is a versatile route to free radical intermediates for chemical synthesis. However, the sequential nature of this multi-step reaction renders the mechanism challenging to probe. Here, we employ a 100 kHz mid-infrared probe in a transient absorption spectroscopy experiment to track the decarboxylation of cyclohexanecarboxylic acid in acetonitrile-d3 over picosecond to millisecond timescales using a photooxidant pair (phenanthrene and 1,4-dicyanobenzene). Selective excitation of phenanthrene at 256 nm enables a diffusion-limited photoinduced electron transfer to 1,4-dicyanobenzene. A measured time offset in the rise of the CO2 byproduct reports on the lifetime (520 ± 120 ns) of a reactive carboxyl radical in solution, and spectroscopic observation of the carboxyl radical confirm its formation as a reaction intermediate. Precise clocking of the lifetimes of radicals generated in situ by an activated C-C bond fission will pave the way for improving the photocatalytic selectivity and turnover.
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| , , , | |
| Springer Science | |
| doi.org/10.1038/s41467-019-13154-w | |
| Nat. Commun. | |
| Organisation | AMOLF |
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Bhattacherje, A., Sneha, M., Lewis-Borrell, L., Tau, O., Clarck, I., & Orr-Ewing, A. (2019). Picosecond to millisecond tracking of a photocatalytic decarboxylation reaction provides direct mechanistic insights. Nat. Commun., 10(1), 5152: 1–7. doi:10.1038/s41467-019-13154-w |
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