Ultrafast Excited State Dynamics and Fluorescence from Vitamin B12 and Organometallic [Co]–C≡C–R Cobalamins
| Autor: | Nicholas A. Miller, Arkaprabha Konar, Elvin V. Salerno, Roseanne J. Sension, Yan Li, Bernhard Kräutler, Christoph Kieninger |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Absorption spectroscopy
Population 010402 general chemistry Photochemistry 01 natural sciences Vibration Article Fluorescence chemistry.chemical_compound 0103 physical sciences Materials Chemistry Emission spectrum Physical and Theoretical Chemistry education education.field_of_study 010304 chemical physics Chemistry Corrin Cobalt Vitamins Tetrapyrrole 0104 chemical sciences Surfaces Coatings and Films Vitamin B 12 Absorption band Excited state |
| Zdroj: | The Journal of Physical Chemistry. B |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Cobalamins are cobalt-centered cyclic tetrapyrrole ring-based molecules that provide cofactors for exceptional biological processes and possess unique and synthetically tunable photochemistry. Typical cobalamins are characterized by a visible absorption spectrum consisting of peaks labeled α, β, and sh. The physical basis of these peaks as having electronic origin or as a vibronic progression is ambiguous despite much investigation. Here, for the first time, cobalamin fluorescence is identified in several derivatives. The fluorescence lifetime is ca. 100-200 fs with quantum yields on the order of 10-6-10-5 because of rapid population of "dark" excited states. The results are compared with the fluorescent analogue with zinc replacing the cobalt in the corrin ring. Analysis of the breadth of the emission spectrum provides evidence that a vibrational progression in a single excited electronic state makes the dominant contribution to the visible absorption band. |
| Databáze: | OpenAIRE |
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