Zinc substitution of cobalt in vitamin B12: Zincobyric acid and zincobalamin as luminescent structural B12‐mimics

Christoph Kieninger, Joseph A. Baker, Maren Podewitz, Klaus Wurst, Steffen Jockusch, Andrew D. Lawrence, Evelyne Deery, Karl Gruber, Klaus R. Liedl, Martin J. Warren, Bernhard Kräutler

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Abstract

Replacing the central cobalt ion of vitamin B12 by other metals has been a long‐held aspiration within the B12‐field. Herein, we describe the synthesis from hydrogenobyric acid of zincobyric acid (Znby) and zincobalamin (Znbl), the Zn‐analogues of the natural cobalt‐corrins cobyric acid and vitamin B12, respectively. The solution structures of Znby and Znbl were studied by NMR‐spectroscopy. Single crystals of Znby were produced, providing the first X‐ray crystallographic structure of a zinc corrin. The structures of Znby and of computationally generated Znbl were found to resemble the corresponding CoII‐corrins, making such Zn‐corrins potentially useful for investigations of B12‐dependent processes. The singlet excited state of Znby had a short life‐time, limited by rapid intersystem crossing to the triplet state. Znby allowed the unprecedented observation of a corrin triplet (ET=190 kJ mol−1) and was found to be an excellent photo‐sensitizer for 1O2 (ΦΔ=0.70).
Original languageEnglish
Pages (from-to)14568-14572
Number of pages5
JournalAngewandte Chemie International Edition
Volume58
Issue number41
Early online date17 Aug 2019
DOIs
Publication statusPublished - 7 Oct 2019

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