Attached proton test for carbon-13 NMR
About: This article is published in Journal of Magnetic Resonance.The article was published on 1982-02-15. It has received 562 citations till now. The article focuses on the topics: Carbon-13 NMR & Proton.
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TL;DR: The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
1,317 citations
TL;DR: In this paper, a compilation of the 13C NMR data of a selected variety of naturally occurring pentacyclic triterpenoids, arranged skeletonwise, is provided.
1,251 citations
TL;DR: The use of 13 carbon nuclear magnetic resonance (NMR) spectroscopy in the molecular characterization of macromolecules has advanced our knowledge into structural areas that have been nearly impossible to measure by other spectroscopic techniques as mentioned in this paper.
Abstract: The use of 13 carbon nuclear magnetic resonance (NMR) spectroscopy in the molecular characterization of macromolecules has advanced our knowledge into structural areas that have been nearly impossible to measure by other spectroscopic techniques. Innovative applications have led to determinations of polymer configurational distributions, comonomer sequence distributions, average sequence lengths, structure and distribution of short chain branches, and analyses of nonreactive end groups. As a result, the importance of 13C NMR to the field of polymer science cannot be overemphasized. The key to the success of 13C-NMR studies in defining polymer molecular structure has been a structural sensitivity which encompasses more than just a few functional groups or carbon atoms. A sensitivity to polymer repeat unit sequences of lengths from two to as many as five, seven, and even nine contiguous repeat units [1,2] has been observed. Of course, any structural technique that senses a unique response from as f...
624 citations
TL;DR: In this article, the Bloch vector model has been used for the analysis of high-resolution NMR spectroscopy, and the main areas of application are signal assignment, sensitivity enhancement, and selective excitation of individual resonances.
Abstract: The introduction of Fourier transform methods has not only remarkably enhanced the sensitivity of high-resolution NMR spectroscopy, thus allowing measurements to be made on less sensitive nuclei of the Periodic Table, but also has paved the way for the development of a large number of new experimental techniques. On the one hand, procedures already known have been improved and can now be performed more rapidly, and, on the other, completely new experimental approaches have become available. This situation resulted mainly from the introduction of programmable pulse transmitters and the separation of the experiment into preparation, evolution, and detection. In particular, the concept of two-dimensional spectroscopy has opened up new possibilities important for the analysis of complicated spectra and is able to provide information previously not accessible. As elsewhere, optimum application of the techniques and correct interpretation of the results require sound understanding of the underlying physical principles. Since a rigorous mathematical treatment is complicated and does not necessarily improve the comprehensibility, this article attempts to give an illustrative presentation of the new pulse techniques within the framework of the Bloch vector model. After a short introduction covering the basic principles, one-dimensional pulse techniques that can be applied using standard experimental equipment are dealt with. The main areas of application are signal assignment, sensitivity enhancement for measurements on less abundant nuclei, and selective excitation of individual resonances. Subsequently, the various techniques of two-dimensional NMR spectroscopy are treated: these enable shift correlations for different types of nuclei to be made, the presentation of spin multiplets without overlap, and the analysis of geometrical relations as well as of chemical exchange phenomena.
336 citations
TL;DR: In this paper, it was shown that the π refocusing pulses can be cycled through all four phases as described by Bodenhausen et al. (J. Magn. Reson. 16, 467 (1974)) for inversion-recovery T1 measurements.
304 citations
References
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TL;DR: In this paper, the application of a new Fourier transform technique to magnetic resonance spectroscopy is explored, which consists of applying a sequence of short rf pulses to the sample to be investigated and Fourier-transforming the response of the system.
Abstract: The application of a new Fourier transform technique to magnetic resonance spectroscopy is explored. The method consists of applying a sequence of short rf pulses to the sample to be investigated and Fourier‐transforming the response of the system. The main advantages of this technique compared with the usual spectral sweep method are the much shorter time required to record a spectrum and the higher inherent sensitivity. It is shown theoretically and experimentally that it is possible to enhance the sensitivity of high resolution proton magnetic resonance spectroscopy in a restricted time up to a factor of ten or more. The time necessary to achieve the same sensitivity is a factor of 100 shorter than with conventional methods. The enhancement of the sensitivity is essentially given by the square root of the ratio of line width to total width of the spectrum. The method is of particular advantage for complicated high resolution spectra with much fine structure.
1,551 citations
581 citations
TL;DR: A simple excitation sequence allows fast recognition of carbon multiplicity in 13C n.m.r. spectra of large molecules, with high precision and sensitivity.
Abstract: A simple excitation sequence allows fast recognition of carbon multiplicity in 13C n.m.r. spectra of large molecules, with high precision and sensitivity.
143 citations