2 Citations (Scopus)

Abstract

Cobalt-carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co-C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co-C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co-NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.

Original languageEnglish (US)
Pages (from-to)1542-1546
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume9
Issue number7
DOIs
StatePublished - Apr 5 2018

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X ray absorption spectroscopy
Cobalt
Ground state
absorption spectroscopy
cobalt
ground state
Photoexcitation
Vitamin B 12
photoexcitation
elongation
Elongation
cleavage
x rays
Carbon
carbon
rings
products
configurations
electronics
mecobalamin

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

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title = "Direct Structural and Chemical Characterization of the Photolytic Intermediates of Methylcobalamin Using Time-Resolved X-ray Absorption Spectroscopy",
abstract = "Cobalt-carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co-C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co-C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co-NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.",
author = "Ganesh Subramanian and Xiaoyi Zhang and Gerdenis Kodis and Qingyu Kong and Cunming Liu and Andrew Chizmeshya and Uwe Weierstall and John Spence",
year = "2018",
month = "4",
day = "5",
doi = "10.1021/acs.jpclett.8b00083",
language = "English (US)",
volume = "9",
pages = "1542--1546",
journal = "Journal of Physical Chemistry Letters",
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TY - JOUR

T1 - Direct Structural and Chemical Characterization of the Photolytic Intermediates of Methylcobalamin Using Time-Resolved X-ray Absorption Spectroscopy

AU - Subramanian, Ganesh

AU - Zhang, Xiaoyi

AU - Kodis, Gerdenis

AU - Kong, Qingyu

AU - Liu, Cunming

AU - Chizmeshya, Andrew

AU - Weierstall, Uwe

AU - Spence, John

PY - 2018/4/5

Y1 - 2018/4/5

N2 - Cobalt-carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co-C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co-C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co-NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.

AB - Cobalt-carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co-C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co-C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co-NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.

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U2 - 10.1021/acs.jpclett.8b00083

DO - 10.1021/acs.jpclett.8b00083

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EP - 1546

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

SN - 1948-7185

IS - 7

ER -