Restricted Motion of Guests Confined in Carceplexes and Capsules

Guest orientation within carceplexes and capsules was determined qualitatively from NMR data, and the molecular mobility of guests was determined via coalescence of 1H NMR signals. Both are highly dependent on guest size and shape, as is interconversion of twistomers. Incarceration of 1,4-thioxane r...

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Bibliographic Details
Published inJournal of organic chemistry Vol. 65; no. 2; pp. 513 - 516
Main Authors Chapman, Robert G, Sherman, John C
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 28.01.2000
Subjects
Magnetic Resonance Spectroscopy
Molecular Conformation
Thermodynamics
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Summary:Guest orientation within carceplexes and capsules was determined qualitatively from NMR data, and the molecular mobility of guests was determined via coalescence of 1H NMR signals. Both are highly dependent on guest size and shape, as is interconversion of twistomers. Incarceration of 1,4-thioxane results in a large (1.8 kcal/mol) constraint on thioxane's conformational mobility (chair-to-chair interconversion). Similar conformational constraints (1.6 kcal/mol) were determined for 1,4-dioxane both when incarcerated in carceplex 1b and when encapsulated reversibly in capsule 3b. Encapsulation-induced conformational constraints of this magnitude are unprecedented, and are particularly striking for the noncovalently linked capsules.
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content type line 23
ISSN:0022-3263
1520-6904
DOI:10.1021/jo991433r