A pseudotetrahedral cobalt(II) complex with a positive axial zero-field splitting parameter of D = 12.7 cm(-1), as determined by high-field EPR spectroscopy, is shown to exhibit slow magnetic relaxation under an applied dc field.

The synthesis and crystal structure of a diiron(II) complex containing a bridging semiquinonate radical are presented. The unique electronic structure of this S = 7/2 complex is examined with spectroscopic (absorption, EPR, resonance Raman) and computational methods.

Our knowledge of xanthine oxidase, the most widely studied enzyme containing the pterin molytxlenum cofactor [l]. has recently been greatly enhanced by the X-ray crystallographic determination of the structure of the closely related aldehyde oxidoreductase from Desulfov/btfo gbas [2,3]. As a result of EPR work, it has long been recognised that these enzymes contain two kinds of pFe2SI centres, ...

The Mn(4)-cluster of photosystem II (PSII) from Synechococcus elongatus was studied by electron paramagnetic resonance (EPR) spectroscopy after a series of saturating laser flashes given in the presence of either methanol or ethanol. Results were compared to those obtained in similar experiments done on PSII isolated from plants. The flash-dependent changes in amplitude of the EPR multiline sig...

Manganese redox enzymes play crucial roles in a variety of biological systems. These include the photosynthetic oxidation of water m dioxygen, the disproport ionat ion of hydrogen peroxide, the disproport ionat ion of superoxide, and ribonucleotide reduction. The Mn sites in two of these systems, the photosynthetic oxygen evolving complex (OEC) and the Mn catalase from L. planrarum have been ch...

The electron paramagnetic resonance (EPR) spectra of the blue copper oxidase ceruloplasmin [ferroxidase, iron (II):oxygen oxidoreductase, EC 1.16.3.1] and of a derivative having the type I (blue) copper centers reversibly bleached are reported. The EPR spectrum of bleached ceruloplasmin has a seven-line superhyperfine structure in the g : formula: (see text) region that is attributed to the pre...

[Cr(III)8M(II)6](12+) (M(II) =Cu, Co) coordination cubes were constructed from a simple [Cr(III) L3 ] metalloligand and a "naked" M(II) salt. The flexibility in the design proffers the potential to tune the physical properties, as all the constituent parts of the cage can be changed without structural alteration. Computational techniques (known in theoretical nuclear physics as statistical spec...

EPR measurements have been carried out on a single crystal of Mn(2+)-doped NH(4)Cl(0.9)I(0.1) at 170-GHz in the temperature range of 312-4.2K. The spectra have been analyzed (i) to estimate the spin-Hamiltonian parameters; (ii) to study the temperature variation of the zero-field splitting (ZFS) parameter; (iii) to confirm the negative absolute sign of the ZFS parameter unequivocally from the t...