We designed basket 1 to comprise a C-3-symmetric hydrophobic cage (477 angstrom(3)) 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 angstrom(3)) in its cavity (K-app = (1.97 +/- 0.02) X 10(3) M-1). The entrapment of the organophosphonate, akin to soman in size (186 angstrom(3)), triggers the transformation of the vesicular material into nanoparticles (100 nm,of type 1 in their bilayer membrane, are unique assemblies and important for obtaining novel sensing devices.