Hinged Molecular Capsules:  Synthesis and Conformational Control via Temperature, pH, or Solvent Composition

Abstract

Three new covalently linked molecular capsules were synthesized from their resorcinarene cavitand precursors in good yields. The capsules undergo reversible conformational switching between the closed "vase" form and the open "kite" form upon temperature or pH variation. The kite conformation obtained via either method in CDCl(3) switches to vase conformation upon addition of polar solvents such as acetone-d(6) or THF-d(8).

Chemistry of Cavitands

“…containing two non bridged hydroxyl groups) cavitands (68) and (69) with tetraazaanthracene (70) leads to opened capsules (cis-71) and (trans-71) consisting of "bottom" and "cap" vase cavitands [45]. containing two non bridged hydroxyl groups) cavitands (68) and (69) with tetraazaanthracene (70) leads to opened capsules (cis-71) and (trans-71) consisting of "bottom" and "cap" vase cavitands [45].…”

A Multi-State, Allosterically-Regulated Molecular Receptor With Switchable Selectivity

“…In order to mimic the properties and regulatory capabilities of reactive cavities in biological machinery, a number of abiotic counterparts have been developed in which the steric profile and the size of molecular cages are regulated via pH changes, − photochemistry, − redox processes, − and coordination chemistry. − Such abiotic systems have exhibited the ability to encapsulate and release small organics, therapeutic agents, and biomolecules as a response to changing chemical environment. While the applications of such structures in phase transfer catalysis, − drug delivery, and sensing have been reported, the usefulness of this approach could be greatly expanded through the development of an abiotic platform to allosterically toggle a single cavitand between an inactive and multiple active states with different recognition properties.…”