Crown ethers flatten in graphene for strong, specific binding
Ethers—simple organic molecules in which an oxygen atom bridges two carbon atoms—are the chemical building blocks of commonplace products including many solvents, propellants, cosmetics and pharmaceuticals. Link them together in large molecular rings and they become scientific royalty—crown ether molecules, whose development led in large part to the 1987 Nobel Prize in chemistry. These crown-shaped rings are important as the initial prototype in host–guest chemistry, a field in which "guest" ions and molecules can be captured within the cavity of a "host" molecule. This capability allows chemists to organize a collection of separately weak bonding interactions, such as the electrostatic bond between an ether oxygen atom and a metal ion, to achieve strong, selective binding. This useful property, called "molecular recognition," is employed for separations, sensing and catalysis.