Nuclear magnetic resonance active nuclei

Both °B and "B nuclei are NMR (nuclear magnetic resonance) active. Because of the high content, high resonant frequency, and lower nuclear quadrupole moment, the NMR spectroscopy of the "B nucleus is generally observed [66]. Trivalent or quadrivalent boron can be comfortably differentiated by means of a chemical shift of "B trivalent>0 ppm>quadrivalent (d value). Thus, the electron density on the boron atom can also estimated with the chanical shift. In this way, "B NMR spectroscopy is a potent tool for structural analyses of boron-containing materials. 

Two rather unusual assays have been developed for superoxide dismutase. Both these assays do not reflect the catalytic activity of the enzyme. The first assay utilizes the unique effect of the metal centers on the relaxation rate of F nucleus of fluoride which can be monitored by nuclear magnetic resonance, whereas the second assay is based on the antigenicity of the proteins. 

MRI is an outstanding noninvasive technology that allows the acquisition of anatomic images with exceptional spatial resolution. The acquisition of images uses the properties of nuclear magnetic resonance (NMR) and among all the NMR active nuclei (such as C, F, and Si) H is the most commonly used nucleus in routine MRI because of its... 

To a physical organic chemist, dipole moment and molecular refraction are electronic properties par excellence—so is optical activity, which is determined, as it were, by the topology of the motion of charge through the molecule under the influence of the electric component of a radiation field so also are the chemical shift of the frequency of nuclear magnetic resonance and the nuclear qvadrupoU coupling constant, both of which serve as sensitive probes into the electronic environment of the nucleus. 

There are also pulse EPR methods that probe the chemical or rather magnetic environment. These are pulse electron nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopy, which allow measuring hyperfine couplings from the unpaired electron spin to surrounding magnetically active nuclei ([20] in Fig. 3 this is a P nucleus). As these experiments are performed in frozen solution (e.g., in all examples of this chapter) or in solids, from the anisotropy and orientation dependence of the hyperfine coupling one can obtain valuable information on the structure up to 1 nm. 

All atomic nuclei possess a characteristic known as nuclear spin (/). However, only those nuclei with nonzero spin are NMR active, undergoing precession when placed in a static magnetic field. The unique precession frequency, known as the Larmor frequency, for each nucleus is dependent on Bq and is unique for each atom. The irradiation frequency coq applied to induce the resonance condition must match the magnetic moment s precession and is related to Bq and magneto-gyric ratio, y, of the nucleus by... 

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