Exceptional Photochemical Stability of the Co–C Bond of Alkynyl Cobalamins, Potential Antivitamins B12 and Core Elements of B12-Based Biological Vectors
| Autor: | Kenneth G. Spears, Roseanne J. Sension, Bernhard Kräutler, Christoph Kieninger, Elvin V. Salerno, Arkaprabha Konar, Klaus Wurst, Robert Salchner, Nicholas A. Miller |
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| Rok vydání: | 2020 |
| Předmět: |
Models
Molecular 010405 organic chemistry Chemistry Core component Molecular Conformation Temperature Cobalt Crystallography X-Ray Photochemical Processes 010402 general chemistry 01 natural sciences Article Carbon 0104 chemical sciences Inorganic Chemistry Vitamin B 12 Computational chemistry Core (graph theory) Physical and Theoretical Chemistry Density Functional Theory |
| Zdroj: | Inorganic Chemistry |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/acs.inorgchem.0c00453 |
| Popis: | Alkynylcorrinoids are a class of organometallic B12 derivatives, recently rediscovered for use as antivitamins B12 and as core components of B12-based biological vectors. They feature exceptional photochemical and thermal stability of their characteristic extra-short Co–C bond. We describe here the synthesis and structure of 3-hydroxypropynylcobalamin (HOPryCbl) and photochemical experiments with HOPryCbl, as well as of the related alkynylcobalamins: phenylethynylcobalamin and difluoro-phenylethynylcobalamin. Ultrafast spectroscopic studies of the excited state dynamics and mechanism for ground state recovery demonstrate that the Co–C bond of alkynylcobalamins is stable, with the Co–N bond and ring deformations mediating internal conversion and ground state recovery within 100 ps. These studies provide insights required for the rational design of photostable or photolabile B12-based cellular vectors. Most alkylcobalamins are photolabile; in contrast, alkynylcobalamins are photostable. Through time-resolved measurements, we demonstrate for three alkynylcobalamins that the Co−C bond is stable (i.e. “locked”), while expansion of the Co−N axial bond (which is “unlocked”) and ring deformations mediate internal conversion and ground state recovery within 100 ps. The barrier for ground state recovery is independent of the R group on the alkynyl ligand. |
| Databáze: | OpenAIRE |
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