Assignment of the axial ligands of ferric ion in low-spin hemoproteins by near-infrared magnetic circular dichroism and electron paramagnetic resonance spectroscopy

1990 ◽  
Vol 112 (13) ◽  
pp. 5003-5011 ◽  
Author(s):  
Paul M. A. Gadsby ◽  
Andrew J. Thomson
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Near Infrared ◽  
Magnetic Circular Dichroism ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Ferric Ion ◽  
Paramagnetic Resonance ◽  
Axial Ligands ◽  
Electron Paramagnetic ◽  
Circular Dichroïsm

Structure-function relationship in antimony corrole photosensitizers: Time-resolved electron paramagnetic resonance and optical study

2007 ◽  
Vol 11 (09) ◽  
pp. 645-651 ◽  
Author(s):  
Linn Wagnert ◽  
Alexander Berg ◽  
Eli Stavitski ◽  
Inna Luobeznova ◽  
Zeev Gross ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Flash Photolysis ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Axial Ligands ◽  
Electron Paramagnetic

Three photosensitizers based on tris-(pentafluorophenyl)antimony corroles that differ in oxidation state and axial ligands, namely, (pyridine) Sb (III)-, (oxo) Sb (V)- and (difluoro) Sb (V) complexes, were studied by time-resolved electron paramagnetic resonance spectroscopy and laser flash photolysis. The magnetic and orientational parameters of the corroles oriented in a nematic liquid crystal as well as their triplet lifetimes in liquid toluene were determined and interpreted in terms of their structure and geometry. The negative zero-field splitting parameter D assigned to all studied corroles is explained by the asymmetric π-electron withdrawal effect caused by perfluorinated peripheral aryl groups, which force the triplet electron spins to align in head-to-tail configuration. The effect of the axial ligands on the photoexcited triplet state properties of the corroles is correlated with their different efficiency to perform photoassisted aerobic oxygenation of some organic molecules. This is explained by the dependence of the main parameters of the photoexcited complexes on the interaction between the central ion and corrole π-system. This interaction is strongly influenced by axial ligands coordination, affecting the macrocycle symmetry, planarity, and rigidity.

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