Journal of the American Chemical Society, Vol.139, No.24, 8086-8089, 2017
Crystalline Supramolecular Gyroscope with a Water Molecule as an Ultrasmall Polar Rotator Modulated by Charge-Assisted Hydrogen Bonds
A new strategy for the construction of crystalline molecular rotors is presented. The combination of a conformation-modifiable macrocyclic host and two cooperative guests affords one supramolecular gyroscope like compound, (t-BuNH3)(18-crown-6) [ZnCl3(H2O)], in which the coordinated water' molecule functions as an ultrasmall polar rotator, revealed by its significant dielectric relaxation and the molecular dynamics simulations. In addition, such a compound can reversibly undergo a polar to-polar phase transition triggered by the changed conformation of the 18-crown-6 host, leading to a switchable on/off rotation of water molecule, well controlled by strength and direction of charge-assisted hydrogen bonds.