Conveners
Young Crystallographers Lightning Talks
- Tina Weigel
- Constantin Buyer (University of Stuttgart, Institute for Inogranic Chemistry)
Previous Hirshfeld Atom Refinement approaches have used non-periodic calculations in order to obtain atomic form factors. We have implemented HAR on the basis of periodic PAW calculations and want to present details and results of this new approach.
We synthesized [Hpyz]$_4$[Sb$_{10}$I$_{34}$] (pyz = N$_2$C$_4$H$_4$), which features the largest discrete halogenido pentelate anion yet. Ions of this type with the general formula [Sb$_{2n}$I$_{3n+4}$]$^{4−}$ are known for $n$ = 1 - 5. With this series of compounds at hand we investigated the influence of the anion size on the optical band gap by experimental and theoretical means to shed...
Crystal structure of the complexes of carboxylated pillar[5]arene, a water-soluble macrocyclic host, with guanidine and amidine drugs (eg. alexidine and pentamidine) provide important information on the host-guest interactions and self-assembly in the solid state. Such complexes can potentially be used in the design of drug delivery systems.
Spin crossover compounds have been recognized as promising candidates, which exhibit large barocaloric effects. From the synchrotron structural data, the temperature dependence of the Fe-N distances can be used to determine the high spin fraction. Then by fitting the temperature dependence of the high spin fraction, we obtained the change in entropy, the change in enthalpy, and the cooperativity.
During the search for novel topological insulators, new fully and partially substituted pseudo one-dimensional compounds were discovered. Extensive investigations into the synthetic pathway via differential scanning calorimetry lead to the two subiodides of the type Bi$_2$[PtBi$_6$I$_{12}$]$_3$ being isolated and synthesized independently. The six weak inter-cluster bridges between the...
3D electron diffraction determines the electrostatic potential, which is dominated by the positively charged nuclei and affected by chemical bonds. We observe this effect from the refined coordinates of hydrogen atoms using the independent atom model, suggesting that aspherical atom models should be used.
Transition-metal nitrides tend to form structures with variable compositions. The catalytic activity of cobalt molybdenum nitrides in ammonia synthesis is highly influenced by the composition of the catalyst. Three mixtures of cobalt(II) nitrate and ammonium heptamolybdate with a controlled molar ratio of Co:Mo (2:1, 1:1, 1:2) were prepared by simple mixing. The obtained mixtures were reduced...
In solid-state chemistry, there is an intriguing number of binary systems lack characterization, especially in combination with the element beryllium. The limited knowledge promises a rich and unusual structural chemistry of this element. The few results concerning Be pnictides include the disordered diamond-like structure of BeP2. Preliminary work based on qualitative evaluation of powder ...
While anticipating the commissioning of the high-intensity time-of-flight neutron powder-diffractometer POWTEX, great efforts were made to optimally exploit the instrument characteristics for future multidimensional Rietveld refinements. The first test data were acquired at the POWGEN instrument of the SNS (Oak Ridge National Laboratory) but using a small segment of the tailor-made POWTEX...
Contamination with diffraction from ice crystals can negatively affect, or even impede, macromolecular structure determination and therefore detecting the resulting artefacts in diffraction data is crucial. However, once the data have been processed it can be very difficult to automatically recognize this problem. To address this, a set of convolutional neural networks named Helcaraxe has been...
Molecular crystals are usually brittle. This fragility poses challenges for their application. Recently, mechanical flexibility in crystalline materials has been discovered. These materials can be divided into being plastically (irreversibly) or elastically (reversibly) bendable. Here we report 4-bromo-6-[(6-chloropyridin-2-ylimino)methyl]phenol (CPMBP) as a plastically bendable crystal and...
Pillarplexes are tubular supramolecular organometallic complexes containing macrocyclic NHC-ligands and eigth metal ions. The structural self-assembly of these motifs is predicted to be governed by non-covalent interactions between the pillarplex cation and its surrounding. Herein, we investigated possible non-covalent interactions with Full Interaction Maps, crystal structure analysis and...
In our work we synthesized polycrystalline Rb3-xKxCu3AlO2(SO4)4 with varying Rb:K ratios. In the experiments we outlined the optimum growth conditions for Rb substituted alumoklyuchevskite synthesized from powder mixtures. First results suggest that Rb and K show a complete miscibility in the polycrystalline powder. In addition, O2 atmosphere is beneficial for building the synthesized phase....
The conversion of Bi$_2$W$_2$O$_9$ to H$_2$W$_2$O$_7$ via HCl treatment has been investigated with in-situ Raman spectroscopy and total scattering / PDF analysis. Previous reports on the selective leaching mechanism of the bismuth oxide interlayer could be verified on the basis of the atomic structure. Our study additionally reveals different rates for the interlayer break-down and subsequent...
Analysis of the crystallite size data with different approaches utilising X-ray diffraction might lead to ambiguous results. For this reason, the use of different analytical techniques is required to confirm the XRD analysis. In the presented study a nanocrystalline iron was also examined with transmission electron microscopy to compare complementary measurements of crystallite sizes.