Processing two-dimensional X-ray diffraction and small-angle scattering data in DAWN 2.

A software package for the calibration and processing of powder X-ray diffraction and small-angle X-ray scattering data is presented. It provides a multitude of data processing and visualization tools as well as a command-line scripting interface for on-the-fly processing and the incorporation of complex data treatment tasks. Customizable processing chains permit the execution of many data processing steps to convert a single image or a batch of raw two-dimensional data into meaningful data and one-dimensional diffractograms. The processed data files contain the full data provenance of each process applied to the data. The calibration routines can run automatically even for high energies and also for large detector tilt angles. Some of the functionalities are highlighted by specific use cases.

Synthesis and structure of Zr(iv)- and Ce(iv)-based CAU-24 with 1,2,4,5-tetrakis(4-carboxyphenyl)benzene.

Two new MOFs denoted as M-CAU-24 (M = Zr, Ce) based on 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4TCPB) were obtained under mild reaction conditions within 15 min. The MOFs with composition [M6(µ3-O)4(µ3-OH)4(OH)4(H2O)4(TCPB)2] crystallise in the scu topology, a connectivity hitherto unreported for Zr-MOFs with tetracarboxylate linker molecules. Zr-CAU-24 exhibits UV/blue ligand-based luminescence.

Opening the gate: framework flexibility in ZIF-8 explored by experiments and simulations.

ZIF-8 is a zeolitic imidazole-based metal-organic framework with large cavities interconnected by narrow windows. Because the small size of the windows, it allows in principle for molecular sieving of gases such as H(2) and CH(4). However, the unexpected adsorption of large molecules on ZIF-8 suggests the existence of structural flexibility. ZIF-8 flexibility is explored in this work combining different experimental techniques with molecular simulation. We show that the ZIF-8 structure is modified by gas adsorption uptake in the same way as it is at a very high pressure (i.e., 14,700 bar) due to a swing effect in the imidazolate linkers, giving access to the porosity. Tuning the flexibility, and so the opening of the small windows, has a further impact on the design of advanced molecular sieving membrane materials for gas separation, adjusting the access of fluids to the porous network.