We describe the first meltable iron-based zeolitic imidazolate
framework (ZIF), denotedMUV-24. This material, elusive
from direct synthesis, is obtained from the thermal treatment of [Fe3(im)6(Him)2], which yields Fe(im)2upon loss of the neutral imidazole molecules. Different crystalline
phase transformations are observed upon further heating, until the
material melts at 482 °C. Vitrification upon cooling of the liquid
phase gives rise to the first Fe-metal–organic framework glass. X-ray total scattering experiments
show that the
tetrahedral environment of the crystalline solids is maintained in
the glass, whereas nanoindentation measurements reveal an increase
in Young’s modulus, in agreement with stiffening upon vitrification.