Study on a 2D layer coordination framework showing order-to-disorder phase transition by ionothermal synthesis

In this study, a two-dimensional (2D) layer-type coordination framework showing solid-to-solid phase transition was ionothermally synthesized. [Zn-2(SO4)(3)(bpy)](THMA)(2) contains an anionic 2D grid layer-type coordination framework and an ordered bulky ammonium cation, THMA(+), with multiple hydrogen bonds. The compound shows reversible order-to-disorder transformation, a result of the cations, which were characterized using X-ray diffraction, differential scanning calorimetry and solid state nuclear magnetic resonance. This study suggests the potential use of coordination frameworks, prepared by ionothermal synthesis, in the design of new type of materials that show solid-to-solid phase transition and high thermal stability for dielectric, ferroelectric and electro-optic functions.