Amorphous Metal-organic Frameworks Research Articles

Structure and Properties of an Amorphous Metal-Organic Framework

ZIF-4, a metal-organic framework (MOF) with a zeolitic structure, undergoes a crystal-amorphous transition on heating to 300 degrees C. The amorphous form, which we term a-ZIF, is recoverable to ambient conditions or may be converted to a dense crystalline phase of the same composition by heating to 400 degrees C. Neutron and x-ray total scattering data collected during the amorphization process are used as a basis for reverse Monte Carlo refinement of an atomistic model of the structure of a-ZIF. The structure is best understood in terms of a continuous random network analogous to that of a-SiO2. Optical microscopy, electron diffraction and nanoindentation measurements reveal a-ZIF to be an isotropic glasslike phase capable of plastic flow on its formation. Our results suggest an avenue for designing broad new families of amorphous and glasslike materials that exploit the chemical and structural diversity of MOFs.

The dynamic aspects of the expression of calcium binding proteins during the development of the dentate granule cells in the mouse hippocampus

2,5-Furandicarboxylic acid (FDA) is a promising renewable building block. It can be derived from cellulosic biomass and therefore poses no competition to the food chain. FDA is considered a valuable replacement for terephthalic acid in the industrial production of poly(ethylene terephthalate). Thus, the biogenic linker was investigated in the formation of metal–organic frameworks (MOFs). Novel crystalline compounds and gels have been synthesized and extensively characterized. The bi-functional linker forms Cu-, Al- and Fe-containing framework materials with hierarchical pore systems and high surface areas. Depending on the synthesis conditions crystalline Cu MOFs have been obtained exhibiting dense packings as well as open microporosity. In contrast, Al and Fe resulted in three-dimensional amorphous metal–organic framework gels with hierarchical pore systems ranging from micro- and meso-up to small macropores. By varying the metal connector as well as synthesis conditions the adsorption properties regarding the pore size and specific surface area can thus be tailored utilizing the versatile biogenic linker FDA that can be produced from renewable resources.