Electron paramagnetic resonance Monitoring

Shortly after, Doetschman and Hutchison reported the first example of a reactive carbene in the crystalline solid state, by preparing diphenylcarbene from diphenyldi-azomethane in mixed crystals with 1,1-diphenylethylene 84 (Scheme 7.23). When the mixed crystals were irradiated, carbene 85 was detected by electron paramagnetic resonance (EPR) and the disappearance of the signal was monitored to determine its kinetic behavior. Two reactions were shown to take place under topochemical... 

To appreciate that in situ electron paramagnetic resonance (EPR) spectroeiectrochemistry only monitors paramagnetic (radical) species. 

Electron paramagnetic resonance can be valuable as a monitor when paramagnetic species are being consumed or formed, as in the acid-catalyzed reaetion (see also Ref. 301)... 

Information about RNA structure and movement is critical for our understanding of how RNA is able to carry out its multifaceted functions. One spectroscopic technique that has shown great promise to study RNA, as well as other biopolymers, is electron paramagnetic resonance (EPR) spectroscopy, also named electron spin resonance (ESR) spectroscopy. EPR is a magnetic resonance technique that monitors the behaviors of unpaired electrons, and has long been used to study structure and dynamics of biomolecules (see recent reviews by Klug and Feix, 2008 Sowa and Qin, 2008). Structural information can be obtained by distance measurements, that is, by determination of distances between two spin-centers, and is the topic of another chapter in this volume (see Chapter 16 in this volume). 

Components of fluidized cracking catalysts (FCC), such as an aluminosilicate gel and a rare-earth (RE) exchanged zeolite Y, have been contaminated with vanadyl naphthenate and the V thus deposited passivated with organotin complexes. Luminescence, electron paramagnetic resonance (EPR) and Mossbauer spectroscopy have been used to monitor V-support interactions. Luminescence results have indicated that the naphthenate decomposes during calcination in air with generation of (V 0)+i ions. After steam-aging, V Og and REVO- formation occurred. In the presence of Sn, Tormation Of vanadium-tin oxide species enhance the zeolite stability in the presence of V-contaminants. 

Electron Paramagnetic Resonance A Powerful Tool for Monitoring Working... 

Capancioni S, Schwach-Abdellaoui K, Kloeti W, et al. In vitro monitoring of poly(ortho ester) degradation by electron paramagnetic resonance imaging. Macromolecules 2003 36(16) 6135-6141. 

The 2 -position has been used to attach other functional groups, either for detection or for further modification. The tertiary structure of TAR RNA has been investigated by the incorporation of the uridine analogue (35). " The analogue incorporates a nitroxide spin-label and may be detected using electron paramagnetic resonance spectroscopy (EPR). A similar spin-label has been attached to the of a guanosine residue, where it was used to monitor hybridisation by EPR. " ... 

Galameau, A. et al., Kinetics of formation of micelle-templated silica mesophases monitored by electron paramagnetic resonance, J. Colloid Interface Set, 201, 105, 1998. 

The elucidation of PrP structure and function often necessitates the incorporation of biophysical probes. These monitors can be fluorescent dyes which enable one to study protein function both in vivo and in vitro by modem fluorescence methods. The incorporation of nuclear magnetic resonance (NMR) sensitive isotopes or spin labels opens the route to NMR and electron paramagnetic resonance (EPR) methodology. In the following these three methods will be briefly discussed in respect of their application in prion research. 

Referring to magnetic resonance methods, nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy, and particularly NMR, is widely used for reaction monitoring however, it is not applicable to all nuclei, and quenching problems may occur in the presence of paramagnetic species. On the other hand, EPR spectroscopy can only detect systems with unpaired electrons. This limits the application potential for this method, and additional complementary... 

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