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231224s2013 xx |||||o 00| ||eng c |
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|a 10.1002/jcc.23204
|2 doi
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|a pubmed24n0747.xml
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|a (DE-627)NLM224323385
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|a (NLM)23335227
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|a DE-627
|b ger
|c DE-627
|e rakwb
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|a eng
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|a Kornobis, Karina
|e verfasserin
|4 aut
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|a Electronic structure of the S1 state in methylcobalamin
|b insight from CASSCF/MC-XQDPT2, EOM-CCSD, and TD-DFT calculations
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|c 2013
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|a Text
|b txt
|2 rdacontent
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|a ƒaComputermedien
|b c
|2 rdamedia
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|a ƒa Online-Ressource
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|a Date Completed 13.09.2013
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|a Date Revised 21.11.2013
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|a published: Print-Electronic
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|a Citation Status MEDLINE
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|a Copyright © 2013 Wiley Periodicals, Inc.
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|a The methylcobalamin cofactor (MeCbl), which is one of the biologically active forms of vitamin B12, has been the subject of many spectroscopic and theoretical investigations. Traditionally, the lowest-energy part of the photoabsorption spectrum of MeCbl (the so-called α/β band) has been interpreted as an S0→S1 electronic transition dominated by π→π* excitations associated with the C=C stretching of the corrin ring. However, a more quantitative band-shape analysis of the α/β spectral region, along with circular dichroism (CD), magnetic CD, and resonance Raman data, has revealed the presence of a second electronic transition that involves the Co-C(Me) bond weakening. Conversely, the lowest-energy excitations based on transient absorption spectroscopy measurements have been interpreted as metal-to-ligand charge transfer (MLCT) transitions. To resolve the existing controversy about the interpretation of the S1 state of MeCbl, calculations have been performed using two independent ab initio wavefunction-based methods. These include the modified variant of the second-order multiconfigurational quasi-degenerate perturbation theory (MC-XQDPT2), using complete active space self-consistent field orbitals, and the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) approach using restricted Hartree-Fock orbitals. It is shown that both ab initio methods provide a consistent description of the S1 state as having an MLCT character. In addition, the performance of different types of functionals, including hybrid (B3LYP, MPW1PW91, TPSSh), generalized-gradient-approximation-type (GGA-type) (BP86, BLYP, MPWPW91), meta-GGA (TPSS), and range-separated (CAM-B3LYP, LC-BLYP) approaches, has been examined and the results of the corresponding time-dependent density functional theory calculations have been benchmarked against the MC-XQDPT2 and EOM-CCSD data. The hybrid functionals support the interpretation in which the S1 state represents a π→π* transition localized on corrin, while pure GGA, meta-GGA, and LC-BLYP functionals produce results consistent with the MLCT assignment
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|a Journal Article
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|a Research Support, Non-U.S. Gov't
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|a Research Support, U.S. Gov't, Non-P.H.S.
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|a mecobalamin
|2 NLM
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|a BR1SN1JS2W
|2 NLM
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|a Vitamin B 12
|2 NLM
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| 650 |
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|a P6YC3EG204
|2 NLM
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|a Kumar, Neeraj
|e verfasserin
|4 aut
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|a Lodowski, Piotr
|e verfasserin
|4 aut
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|a Jaworska, Maria
|e verfasserin
|4 aut
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|a Piecuch, Piotr
|e verfasserin
|4 aut
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|a Lutz, Jesse J
|e verfasserin
|4 aut
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|a Wong, Bryan M
|e verfasserin
|4 aut
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|a Kozlowski, Pawel M
|e verfasserin
|4 aut
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|i Enthalten in
|t Journal of computational chemistry
|d 1984
|g 34(2013), 12 vom: 05. Mai, Seite 987-1004
|w (DE-627)NLM098138448
|x 1096-987X
|7 nnns
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| 773 |
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|g volume:34
|g year:2013
|g number:12
|g day:05
|g month:05
|g pages:987-1004
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|u http://dx.doi.org/10.1002/jcc.23204
|3 Volltext
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