Journal article
Cobalt(II) "Scorpionate" complexes as electronic ground state models for cobalt-substituted zinc enzymes: Structure investigation by magnetic circular dichroism
Journal of inorganic biochemistry, Vol.203, pp.110876-110876
02/2020
DOI: 10.1016/j.jinorgbio.2019.110876
PMID: 31756558
Abstract
Zinc centers in pseudo-tetrahedral geometry are widely found in biology, often with three histidine ligands from protein. The trispyrazolylborate "scorpionate" ligand is used as a model for this tris(histidine) motif, and spectroscopically active Co
is often used as a substitute for spectroscopically silent Zn
. In this work, four pseudo-tetrahedral scorpionate complexes with the formula (Tp
)CoL, where Tp
= hydrotris(3-tert-butyl, 5-2'-thienyl-pyrazol-1-yl)borate anion and L = Cl
, N
, NCO
, or NCS
, were studied using variable-temperature, variable-field magnetic circular dichroism (VTVH MCD) spectroscopy. The major goal was to determine the axial and rhombic zero field splitting (ZFS) parameters (D and E, respectively) of these S = 3/2 systems and compare these ZFS parameters to those determined previously by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy on the same (L = Cl
and NCS
) or closely related complexes. Additionally, HFEPR studies were undertaken here on the complexes with L = N
, NCO
. Crystal structures for these two complexes are also first reported here. The values of D determined by VTVH MCD were + 12.8 and + 3.6 cm
for the L = Cl
and NCS
complexes, respectively. These values are in close agreement with those for the same complexes as previously determined by HFEPR. The values of D determined by VTVH MCD were + 3.0 and + 6.6 cm
for the L = N
and NCO
complexes, respectively. These values were not as close to those determined by HFEPR in the present study, which are 4.2 cm
≤ |D| ≤ 5.6 cm
in Tp
CoN
, and 8.3 cm
≤ |D| ≤ 11.0 cm
in Tp
CoNCO. The bands in MCD spectra of these complexes were assigned in C
symmetry and a complete ligand-field analysis of the MCD data was made using the Angular Overlap Model (AOM), which is compared to previous results.
Details
- Title: Subtitle
- Cobalt(II) "Scorpionate" complexes as electronic ground state models for cobalt-substituted zinc enzymes: Structure investigation by magnetic circular dichroism
- Creators
- Nicholas M Plugis - Middlebury College (United States, MiddleburyNathan D Rudd - Middlebury College (United States, MiddleburyJ Krzystek - National High Magnetic Field LaboratoryDale C Swenson - University of IowaJoshua Telser - Roosevelt UniversityJames A Larrabee - Middlebury College (United States, Middlebury
- Resource Type
- Journal article
- Publication Details
- Journal of inorganic biochemistry, Vol.203, pp.110876-110876
- DOI
- 10.1016/j.jinorgbio.2019.110876
- PMID
- 31756558
- ISSN
- 0162-0134
- eISSN
- 1873-3344
- Grant note
- CHE0848433 / National Science Foundation CHE1905005 / National Science Foundation CHE0820965 / National Science Foundation
- Language
- English
- Date published
- 02/2020
- Academic Unit
- Chemistry
- Record Identifier
- 9984622046202771
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