Pochorovski I, Ebert M.-O, Gisselbrecht J.-P, Boudon C, Schweizer WB, Diederich F
* ETH Zürich, Switzerland and Université de Strasbourg, France
Redox-Switchable Resorcin[4]arene Cavitands: Molecular Grippers.
J. Am. Chem. Soc. 2012;
134: 14702-14705
Key words
diquinone-based cavitands - molecular machines - resorcin[4]arenes
Significance
Here, a diquinone-based resorcin[4]arene cavitand goes from a kite to a vase form
when reduced. The vase forms via hydrogen bonding between the central diols and the
oxygens of the amides. This vase is stable even at
–80 °C and can be used to capture the small molecule guests shown above. The molecules
are shown in order of increasing association constant K
a
. The vase cavitand releases the guests upon oxidation.
Comment
Both the kite and vase form are stable in deuterated chloroform, tetrahydrofuran,
and mesitylene. After two to four days, the reduced form reverts into the oxidized
form. A crystal structure of the reduced form has a 7.3° cavity, which allows it to
encapsulate the solvent molecule mesitylene, as well as the larger guest molecules.
