Abstract

We carried out three-pulse ESEEM studies on vanadyl phthalocyanine (VOPc), vanadyl octaethylporphyrin (VO OEP), vanadyl tetraphenyl porphyrin (VO TPP) and vanadyl acetylacetonate (Vo(acad)2) in pyridine solution. The multi-frequency ESEEM, angular selective ESEEM, and tau-suppression techniques have been used to make an unambiguous assignment of ESEEM features. The four directly coordinated nitrogens in the equatorial plane of these vanadyl porphyrin complexes are found to be inequivalent. For VOPs, the hyperfine coupling along the orientation perpendicular to the V=O axis equal to: 6.6, 6.9, 7.2, and 7.6 MHz; the hyperfine coupling along the V=O axis, however, is a single value, 7.8 MHz. The same type of inequivalence in the perpendicular orientation and equivalence in the parallel orientation of nitrogen couplings are observed in VO OEP and VO TPP. With angular selective ESEEM measurements on Vo(acac)2-pyridine and spectral simulation, we are able to determine the nature of whether pyridine ligation is equatorial or axial. A paper submitted is under revision.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR002583-11A1
Application #
5224122
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
11
Fiscal Year
1996
Total Cost
Indirect Cost

  Publications

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