Solvation structures of cyclic compounds: the crown ethers

Crown ethers are cyclic molecules formed by joining ether groups into a ring. These compounds have many interesting solution properties, including their ability to bind strongly to certain cations. We request 4 days of beamtime on NIMROD to study the structure of concentrated and dilute solutions of 15-crown-5 (15 atoms in the ring, and 5 ether groups) in two different solvents: Methanol and Dimethyl Ether (DME). This proposal will enable us to determine the microscopic solvation of crown ethers in the presence and absence of hydrogen bonding, both with and without complexed ions. These experiments will exploit the unique ability of neutron scattering to elucidate of liquid structure, and will use isotopic labelling of the solvent molecules to highlight very subtle structural features. This approach will enable us to answer many fundamental questions regarding crown ether solvation.