Nuclear magnetic resonance structure determination

Schraml, J. and Bellama J.M., Si nuclear magnetic resonance, in Determination of Organic Structures by Physical Methods, Vol. 6, Nachod, F.C. and Zuckerman, J.J., Eds., Academic Press, New York, 1976. 

Present day techniques for structure determination in carbohydrate chemistry are sub stantially the same as those for any other type of compound The full range of modern instrumental methods including mass spectrometry and infrared and nuclear magnetic resonance spectroscopy is brought to bear on the problem If the unknown substance is crystalline X ray diffraction can provide precise structural information that m the best cases IS equivalent to taking a three dimensional photograph of the molecule... 

Nuclear magnetic resonance (NMR) spectroscopy (Section 13 3) A method for structure determination based on the effect of molecular environment on the energy required to promote a given nucleus from a lower energy spin state to a higher energy state... 

TF Flavel. An evaluation of computational strategies for use m the determination of protein structure from distance constraints obtained by nuclear magnetic resonance. Prog Biophys Mol Biol 56 43, 1991. 

GM Clore, MA Robien, AM Gronenborn. Exploring the limits of precision and accuracy of protein structures determined by nuclear magnetic resonance spectroscopy. J Mol Biol 231 82-102, 1993. 

Billeter, M., et al. Determination of the nuclear magnetic resonance solution structure of an Antennapedia home-odomain DNA complex. /. Mol. Biol. 234 1084-1097, 1993. 

Wiithrich, K. Protein structure determination in solution by nuclear magnetic resonance spectroscopy. Science 243 45-50, 1989. 

As with other diffraction techniques (X-ray and electron), neutron diffraction is a nondestructive technique that can be used to determine the positions of atoms in crystalline materials. Other uses are phase identification and quantitation, residual stress measurements, and average particle-size estimations for crystalline materials. Since neutrons possess a magnetic moment, neutron diffraction is sensitive to the ordering of magnetically active atoms. It differs from many site-specific analyses, such as nuclear magnetic resonance, vibrational, and X-ray absorption spectroscopies, in that neutron diffraction provides detailed structural information averaged over thousands of A. It will be seen that the major differences between neutron diffraction and other diffiaction techniques, namely the extraordinarily... 

Nuclear magnetic resonance has revolutionized structure determination of iminium salts. A compilation of various resonances for acyclic and cyclic iminium salts are given in Tables 3 and 4 for comparison purposes and for determination of trends. It should be noted that the simplest symmetrically... 

Quadrupole coupling constants for molecules are usually determined from the hyperfine structure of pure rotational spectra or from electric-beam and magnetic-beam resonance spectroscopies. Nuclear magnetic resonance, electron spin resonance and Mossbauer spectroscopies are also routes to the property. There is a large amount of experimental data for and halogen-substituted molecules. Less data is available for deuterium because the nuclear quadrupole is small. 

Determining the structure of an organic compound was a difficult and time-consuming process in the 19th and early 20th centuries, but powerful techniques are now available that greatly simplify the problem. In this and the next chapter, we ll look at four such techniques—mass spectrometry (MS), infrared (IR) spectroscopy, ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR)—and we U see the kind of information that can be obtained from each. 

Nuclear magnetic resonance (NMR) spectroscopy is the most valuable spectroscopic technique available to organic chemists. It s the method of structure determination that organic chemists turn to first. 

We saw in Chapter 12 that mass spectrometry gives a molecule s formula and infrared spectroscopy identifies a molecule s functional groups. Nuclear magnetic resonance spectroscopy does not replace either of these techniques rather, it complements them by "mapping" a molecule s carbon-hydrogen framework. Taken together, mass spectrometry, JR, and NMR make it possible to determine the structures of even very complex molecules. 

CHAPTER 13 Structure Determination Nuclear Magnetic Resonance Spectroscopy... 

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