Structural details of metal-organic frameworks by quantitative X-ray microscopy

Abstract High-resolution X-ray microscopy was used to study the volumetric details of metal-organic framework (MOF) single crystals formed by coordination bonds between copper nitrate and an organic ligand. The three-dimensional information of individual crystals was visualized with submicron resolution, from the virtual slicing of the crystals. Density is one of the basic material properties, but conventional methods cannot provide high resolution mapping. To gain further information on material properties, quantification of the density inside individual crystal were made. The metal salt precursor was used as a standard. By using the same acquisition and reconstruction parameters for the sample and the standard, a correlation between the X-ray attenuation/intensity inside one crystal and its density was established. This correlation allowed the determination of the amount and the spatial distribution of material inside one MOF crystal. The results could provide guidance for future crystal design.