A
supramolecular assembly or "supermolecule" is a well defined complex of molecules held together by
noncovalent bonds. While a supramolecular assembly can be simply composed of two molecules (e.g., a
DNA double helix or an
inclusion compound), it is more often used to denote larger complexes of molecules that form sphere-, rod-, or sheet-like species. The dimensions of supramolecular assemblies can range from nanometers to micrometers. Thus they allow access to nanoscale objects using a
bottom-up approach in far fewer steps than a single molecule of similar dimensions.