Fixing the Conformation of Calix[4]arenes: When Are Three Carbons Not Enough? - Archive ouverte HAL Access content directly
Journal Articles Chemistry - A European Journal Year : 2018

Fixing the Conformation of Calix[4]arenes: When Are Three Carbons Not Enough?

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Susan Matthews
  • Function : Author
Samy Cecioni
  • Function : Author
  • PersonId : 766096
  • IdRef : 164008861
Colin Macdonald
  • Function : Author
David Hughes
  • Function : Author
Garth Jones
  • Function : Author
Stephen Ashworth
  • Function : Author

Abstract

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 1H 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.

Dates and versions

hal-02121302 , version 1 (06-05-2019)

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Susan Matthews, Samy Cecioni, John O'Brien, Colin Macdonald, David Hughes, et al.. Fixing the Conformation of Calix[4]arenes: When Are Three Carbons Not Enough?. Chemistry - A European Journal, 2018, 24 (17), pp.4436-4444. ⟨10.1002/chem.201705955⟩. ⟨hal-02121302⟩
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