The mechanical side of bonding

The newest bond in chemistry might not be a chemical bond at all. A mechanical bond is formed when one molecule is threaded through another, then cyclised or otherwise modified to trap the two components in a physically interlocked state – like two rings in a chain link fence. Compared to the other bonds in the chemist’s lexicon such as the covalent bond, or even non-covalent linkages like the hydrogen bond, mechanical bonds are quite unusual. Mechanical bonds are also unlike other chemical bonds in that they don’t involve charge or the sharing of electrons.

The mechanical bond’s unconventional nature – including the large amplitude motions it permits between bonded parts – is also its key appeal. Making mechanical bonds gives access to structures with properties that cannot easily be accessed any other way.