Assembly of Amphiphilic Baskets into Stimuli-Responsive Vesicles. Developing a Strategy for the Detection of Organophosphorus Chemical Nerve Agents

We designed basket 1 to comprise a C3-symmetric hydrophobic
cage (477 Å3)
at its southern edge and three polar ammonium caps at the northern
edge. This amphiphilic molecule was observed to assemble into large
unilamellar vesicles (350 nm, TEM) in water and thereby entrap dimethyl
phenylphosphonate (184 Å3) in its cavity (Kapp = (1.97 ± 0.02) × 103 M–1). The entrapment of the organophosphonate,
akin to soman in size (186 Å3), triggers the transformation
of the vesicular material into nanoparticles (100 nm, TEM). Stimuli-responsive
vesicles, containing baskets of type 1 in their bilayer
membrane, are unique assemblies and important for obtaining novel
sensing devices.