Theoretical analysis of electronic absorption spectra of vitamin B₁₂ models

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DOIResolve DOI: http://doi.org/10.1063/1.1405436
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TypeArticle
Journal titleThe Journal Of Chemical Physics
Volume115
Issue16
Pages75227533; # of pages: 12
Subjectmolecular biophysics; orbital calculations; organic compounds; spectra; transition moments; ultraviolet spectra
AbstractTime-dependent density-functional theory (TD-DFT) is applied to analyze the electronic absorption spectra of vitamin B₁₂. To accomplish this two model systems were considered: CN-[CoIII-corrin]-CN (dicyanocobinamide, DCC) and imidazole-[CoIII-corrin]-CN (cyanocobalamin, ImCC). For both models 30 lowest excited states were calculated together with transition dipole moments. When the results of TD-DFT calculations were directly compared with experiment it was found that the theoretical values systematically overestimate experimental data by approximately 0.5 eV. The uniform adjustment of the calculated transition energies allowed detailed analysis of electronic absorption spectra of vitamin B₁₂ models. All absorption bands in spectral range 2.0�5.0 eV were readily assigned. In particular, TD-DFT calculations were able to explain the origin of the shift of the lowest absorption band caused by replacement of the�CN axial ligand by imidazole.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
NPARC number12333675
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Record identifier4bb39b5a-14b9-42b2-851a-e50af88210de
Record created2009-09-10
Record modified2016-05-09
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