Isostructural phase transition and tunable water rotation within a unique solid rotor system

Through the combined techniques of variable-temperature X-ray structure analysis, dielectric measurement, isotope substitution and molecular dynamics simulation, we investigate a new supramolecular gyroscope (t-BuNH3)(18-crown-6)[ZnBr3(H2O)]. It undergoes an unusual isostructural phase transition, which is different to the non-isostructural one of the chlorine substituted analogue we reported previously. In addition, solid solutions of them can be afforded, with tunable phase transition temperature and the related properties. The comparative analysis of these homologous supramolecular gyroscopes provides an in-depth insight for understanding the mechanism of the rarely observed temperature-induced isostructural phase transition as well as modulating the dipole rotation in crystals.