Controlling molecular self-organization: Formation of nanometer-scale spheres and tubules

Amphiphilic polyhedron-shaped p-sulfonatocalix[4]arene building blocks, whi ch have been previously shown to assemble into bilayers in an antiparallel fashion, have been assembled in a parallel alignment into spherical and hel ical tubular structures by the addition of pyridine N-oxide and Lanthanide ions. Crystallographic studies revealed how metal ion coordination and subs trate recognition direct the formation of these supramolecular assemblies. The addition of greater amounts of pyridine N-oxide changed the curvature o f the assembling surface and resulted in the formation of extended tubules.