A systems approach to controlling supramolecular architecture and emergent solution properties via host-guest complexation in water

The assembly behavior of aryl/alkyl imidazolium ionic liquid salts in aqueous solution has been investigated. These salts undergo self-assembly into one-dimensional stacks via hydrophobic and π-π interactions upon increasing concentration, which led to a substantial increase in the solution viscosity in water. Addition of the macrocyclic host molecules cucurbitn]urils (CBn]) were found to effectively alter the supramolecular assemblies, as evidenced from the dramatic increase (by CB7]) and decrease (by CB8]) in solution viscosity and aggregation size in water, on account of the different binding stoichiometries, 1:1 complexation with CB7] and 2:1 complexation with CB8]. Furthermore, the aggregate architectures were controllably modified by competitive guests for the CBn] hosts. This complex supramolecular systems approach has tremendous implications in the fields of molecular sensor design, nonlinear viscosity modification, and controlled release of target molecules from a defined supramolecular scaffold in water.