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Quantification and visualization of the anisotropy effect in NMR spectroscopy by through-space NMR shieldings

  • The anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena asThe anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena as are pseudo-, spherical, captodative, homo-and chelatoaromaticity, to characterize the pi-electronic structure of, for example, fulvenes, fulvalenes, annulenes or fullerenes and to differentiate aromatic and quinonoid structures.show moreshow less

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Metadaten
Author:Erich Kleinpeter
DOI:https://doi.org/10.1016/B978-0-12-800184-4.00003-5
ISBN:978-0-12-800184-4
ISSN:0066-4103 (print)
Parent Title (English):Annual reports on NMR spectroscopy
Parent Title (English):Annual Reports on NMR Spectroscopy
Publisher:Elsevier
Place of publication:San Diego
Editor:GA Webb
Document Type:Review
Language:English
Year of first Publication:2014
Year of Completion:2014
Release Date:2017/03/27
Tag:Anisotropy effect; Aromatic or quinonoid; Aromaticity; Binding pocket position; Chelatoaromaticity; Diastereomers assignment; Ring-current effect; Stereochemistry; Supramolecular compounds; Through-space NMR shielding (TSNMRS)
Volume:82
Pagenumber:52
First Page:115
Last Page:166
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Peer Review:Referiert