Crystal Melting and Vitrification Behaviors of the Three-Dimensional Nitrile-Based Metal–Organic Framework
A three-dimensional (3D) metal–organic framework [Ag(pL2)(CF3SO3)]·2C6H6 (pL2 = 1,3,5-tris(4-ethynylbenzonitrile)benzene), composed of Ag+ and tripodal nitrile ligands, was prepared to enable the investigation of its crystal melting and vitrification behaviors. The guest-free state showed a crystal melting at 271 degC, and the liquid state transformed into a glassy state via cooling. The vitrification of the crystalline compound into an amorphous glassy state was also obtained by mechanical hand-grinding. The structure of the glassy state retained the 3D networked structure, confirmed by FT-IR, X-ray absorption, and scattering measurements. The mechanically induced glass showed a small uptake of CO2 and a strong affinity for benzene and H2O vapors, confirmed by gas sorption isotherms. Studies on powder X-ray diffraction have revealed that a vitrified structure returns to the original 3D crystalline structure by exposure to these vapors.
- This article is part of the themed collection: Cooperative phenomena in framework materials