Electron Paramagnetic Resonance Techniques

R.S. Alger, Electron Paramagnetic Resonance Techniques and Applications, Wiley-Interscience, New York, NY, 1968. 

R. N. Adams, J. Electroanal. Chem. 8 252 (1964). Application of Electron Paramagnetic Resonance Techniques in Electrochemistry. ... 

A reaction mechanism for the above reactions was proposed which consists of initial formation of the copper precursor complexes of Fig. 3 (without coordinated phenolate), coordination of phenolate, electron transfer from phenolate to Cu2+ and subsequent reduction to Cu1+ with formation of a phenoxy radical, and reoxidation of Cu1+ to Cu2+ with oxygen. Various copper(II) catalysts having different stereochemistries (octahedral or tetrahedral coordination) due to coordination of amines like pyridine (Py) or acetate (OAc) groups in different ligand sites were observed by NMR and electron paramagnetic resonance techniques. 

Valuable spectroscopic studies on the dithiolene chelated to Mo in various enzymes have been enhanced by the knowledge of the structure from X-ray diffraction. Plagued by interference of prosthetic groups—heme, flavin, iron-sulfur clusters—the majority of information has been gleaned from the DMSO reductase system. The spectroscopic tools of X-ray absorption spectroscopy (XAS), electronic ultraviolet/visible (UV/vis) spectroscopy, resonance Raman (RR), MCD, and various electron paramagnetic resonance techniques [EPR, electron spin echo envelope modulation (ESEEM), and electron nuclear double resonance (ENDOR)] have been particularly effective probes of the metal site. Of these, only MCD and RR have detected features attributable to the dithiolene unit. Selected results from a variety of studies are presented below, chosen because their focus is the Mo-dithiolene unit and organized according to method rather than to enzyme or type of active site. 

Alger RS (1968) Electron paramagnetic resonance techniques and applications Wiley-Interscience, New York, 580pp... 

The chemistry of ascorbic acid free radicals is reviewed. Particular emphasis is placed on identification and charac-terization of ascorbate radicals by spectrophotometric and electron paramagnetic resonance techniques, the kinetics of formation and disappearance of ascorbate free radicals in enzymatic and nonenzymatic reactions, the effect of pH upon the spectral and kinetic properties of ascorbate anion radical, and chemical reactivity of ascorbate free radicals. 

Electron Paramagnetic Resonance Techniques for Measuring Distances in Proteins... 

Meyer BK, Hofmann DM, Stadler W, Petrova-Koch V, Koch F, Omhng P, Emanuelsson P (1993) Defects in porous silicon investigated by optically detected and by electron paramagnetic resonance techniques. Appl Phys Lett 63(15) 2120-2122... 

The diffusion of Mn2+ in single crystals was studied by using the electron paramagnetic resonance technique. The data could be described by ... 

However, it is still not conclusively known how polysulfide ring/chain participates in the whole cyding and whether the discharge and charge processes follow the same pathway. Herein, we demonstrate the direct observation of sulfur radicals by using in-situ electron paramagnetic resonance technique. 

In investigations of the deformation and fracture of high polymer solids [4-67] by electron paramagnetic resonance techniques (EPR) similar experimental problems arise as during the above mentioned apphcations of EPR ... 

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