journal menu
abstracts
The importance of defects for inorganic functional framework materials is well established, being crucial for properties from relaxor ferroelectricity to superconductivity. The corresponding study of defects in metal-organic frameworks (MOFs) is still however in its infancy. Recent studies have established that ligand-absence defects can be controllably introduced into frameworks and that these defects can drastically improve the material properties, but have so far shown no evidence of correlation between defects. Much of this research has focussed on UiO-66, a zirconium dicarboxylate MOF that was amongst the first very stable MOFs to be discovered.[1] As a result of its stability, it and its derivatives have been investigated for a wide range of properties including photo- and Brønsted acid catalysis, sensing and gas sorption properties. The ability to introduce defects has been demonstrated to substantially enhance both the sorption and catalytic properties of UiO-66.[2][3] We have demonstrated, using a combination of powder X-ray diffraction, total scattering and electron diffraction measurements, that UiO-66 can be engineered, under the appropriate synthetic conditions, to accommodate correlated defect nanodomains. These correlations offer exciting opportunities for manipulating the physical properties, including mass transport, chemical activity and mechanical flexibility.
abstracts
Much attention has recently been focused flexible metal-organic frameworks (MOFs), or Soft Porous Crystals, that behave in a remarkable stimuli-responsive fashion upon guest adsorption, temperature, or mechanical pressure. It was shown that these different stimuli-driven structural transitions can be rationalized by combining an understanding of adsorption thermodynamics and mechanical properties of the host phases. We will show how the combination of a large range of molecular simulation methods can assess the extent of flexibility of known MOF structures, as well as give physical insight into their deformation mechanisms, and predict the occurrence of new phases. In particular, we will demonstrate the breathing nature of recently synthesized MOFs CAU-13 and NOTT-300, that have not been observed experimentally.
