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Fixing the Conformation of Calix[4]arenes: When Are Three Carbons Not Enough?
Matthews, Susan E; Cecioni, Samy; O'Brien, John E; MacDonald, Colin J; Hughes, David L; Jones, Garth A; Ashworth, Stephen H; Vidal, Sébastien.
Afiliação
  • Matthews SE; School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • Cecioni S; Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, CO2-Glyco, UMR 5246, CNRS, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France.
  • O'Brien JE; School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland.
  • MacDonald CJ; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • Hughes DL; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • Jones GA; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • Ashworth SH; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • Vidal S; Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, CO2-Glyco, UMR 5246, CNRS, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France.
Chemistry ; 24(17): 4436-4444, 2018 Mar 20.
Article em En | MEDLINE | ID: mdl-29338100
Calix[4]arenes are unique macrocycles that through judicious functionalisation at the lower rim can be either fixed in one of four conformations or remain conformationally flexible. Introduction of propynyl or propenyl groups unexpectedly provides a new possibility; a unidirectional conformational switch, with the 1,3-alternate and 1,2-alternate conformers switching to the partial cone conformation, whilst the cone conformation is unchanged, under standard experimental conditions. Using 1 H NMR kinetic studies, rates of switching have been shown to be dependent on the starting conformation, upper-rim substituent, where reduction in bulk enables faster switching, solvent and temperature with 1,2-alternate conformations switching fastest. Ab initio calculations (DFT) confirmed the relative stabilities of the conformations and point towards the partial cone conformer being the most stable of the four. The potential impact on synthesis through the "click" reaction has been investigated and found not to be significant.
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Texto completo: 1 Base de dados: MEDLINE Idioma: En Revista: Chemistry Assunto da revista: QUIMICA Ano de publicação: 2018 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Idioma: En Revista: Chemistry Assunto da revista: QUIMICA Ano de publicação: 2018 Tipo de documento: Article