Ring current and anisotropy effects on OH chemical shifts in resonance-assisted intramolecular H-bonds
- Ring current effects on resonance-assisted and intramolecularly bridged hydrogen bond protons for 10-hydroxybenzo[h]quinoline 1 and a number of related compounds were calculated and the through-space NMR shieldings (TSNMRS) obtained hereby visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. These calculations revealed that this through-space effect is comparably large (up to 2 ppm) dependent on the position of the intramolecularly bridged OH proton, and therefore, contribute considerably to the chemical shift of the latter making it questionable to use delta(OH)/ppm in the estimation of intramolecular hydrogen bond strength without taking this into account. Furthermore, the anisotropy effects of additional groups on the aromatic moiety (e.g. the carbonyl group in salicylaldehyde or in o-hydroxyacetophenone of ca. 0.6 ppm deshielding) should also be considered. These through-space effects need to be taken into account when using OH chemical shifts to estimate hydrogen bond strength.
Author details: | Poul Erik HansenORCiD, Andreas KochORCiDGND, Erich KleinpeterORCiDGND |
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DOI: | https://doi.org/10.1016/j.tetlet.2018.05.006 |
ISSN: | 0040-4039 |
Title of parent work (English): | Tetrahedron letters |
Publisher: | Elsevier |
Place of publishing: | Oxford |
Publication type: | Article |
Language: | English |
Date of first publication: | 2018/05/03 |
Publication year: | 2018 |
Release date: | 2021/11/19 |
Tag: | Anisotropy effect; Iso-chemical-shielding surfaces (ICSS); RA-intramolecular hydrogen bond; Ring current effect; Through-space NMR shieldings (TSNMRS) |
Volume: | 59 |
Issue: | 23 |
Number of pages: | 5 |
First page: | 2288 |
Last Page: | 2292 |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
Peer review: | Referiert |