Counterion influence on chemical shifts in strychnine salts
Copyright © 2013 John Wiley & Sons, Ltd.
| Veröffentlicht in: | Magnetic resonance in chemistry : MRC. - 1985. - 51(2013), 5 vom: 25. Mai, Seite 292-8 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
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2013
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| Zugriff auf das übergeordnete Werk: | Magnetic resonance in chemistry : MRC |
| Schlagworte: | Journal Article Research Support, U.S. Gov't, Non-P.H.S. Carbon Isotopes Salts Solvents Chloroform 7V31YC746X Hydrogen 7YNJ3PO35Z Strychnine mehr... |
| Zusammenfassung: | Copyright © 2013 John Wiley & Sons, Ltd. The highly toxic plant alkaloid strychnine is often isolated in the form of the anion salt of its protonated tertiary amine. Here, we characterize the relative influence of different counterions on (1)H and (13)C chemical shifts in several strychnine salts in D2O, methanol-d4 (CD3OD), and chloroform-d (CDCl3) solvents. In organic solvents but not in water, substantial variation in chemical shifts of protons near the tertiary amine was observed among different salts. These secondary shifts reveal differences in the way each anion influences electronic structure within the protonated amine. The distributions of secondary shifts allow salts to be easily distinguished from each other as well as from the free base form. Slight concentration dependence in chemical shifts of some protons near the amine was observed for two salts in CDCl3, but this effect is small compared with the influence of the counterion. Distinct chemical shifts in different salt forms of the same compound may be useful as chemical forensic signatures for source attribution and sample matching of alkaloids such as strychnine and possibly other organic acid and base salts |
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| Beschreibung: | Date Completed 17.10.2013 Date Revised 21.11.2013 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1097-458X |
| DOI: | 10.1002/mrc.3945 |