Small‐pore zeolites such as chabazite (CHA) are excellent candidates for the selective separation of CO2; however, the current synthesis involves several steps and the use of organic structure‐directing agent (OSDA), increasing their cost and energy requirements. We report the synthesis of small‐pore zeolite crystals (aluminosilicate) with CHA‐type framework structure by direct synthesis in a colloidal suspension containing a mixture of inorganic cations only (Na+, K+, and Cs+). The location of CO2 molecules in the host structure was revealed by 3D electron diffraction (3D ED). The high sorption capacity for CO2 (3.8 mmol g−1 at 121 kPa), structural stability and regenerability of the discreate CHA zeolite nanocrystals is maintained for 10 consecutive cycles without any visible degradation. The CHA zeolite (Si:Al=2) reaches an almost perfect CO2 storage capacity (8 CO2 per unit cell) and high selectivity (no CH4 was adsorbed).

Dynamical diffraction effects are usually considered a nuisance for structure analysis from continuous-rotation 3D electron diffraction (3D ED) data like cRED and MicroED. Here we demonstrate that by accounting for these effects during the structure refinement, significantly improved models can be obtained in terms of accuracy and reliability with up to four-fold reduction of the noise level in difference Fourier maps in comparison to the standard structure determination routines that ignore dynamical diffraction. As dynamical diffraction effects break the inversion symmetry of the diffraction, they allow a quick, easy, and reliable determination of the absolute structure of chiral crystals.

Continuous-rotation 3D electron diffraction methods are increasingly popular for the structure analysis of very small organic molecular crystals and crystalline inorganic materials. Dynamical diffraction effects cause non-linear deviations from kinematical intensities that present issues in structure analysis. Here, a method for structure analysis of continuous-rotation 3D electron diffraction data is presented that takes multiple scattering effects into account. Dynamical and kinematical refinements of 12 compounds—ranging from small organic compounds to metal–organic frameworks to inorganic materials—are compared, for which the new approach yields significantly improved models in terms of accuracy and reliability with up to fourfold reduction of the noise level in difference Fourier maps. The intrinsic sensitivity of dynamical diffraction to the absolute structure is also used to assign the handedness of 58 crystals of 9 different chiral compounds, showing that 3D electron diffraction is a reliable tool for the routine determination of absolute structures.

New superspace models with different modulation amplitudes indicate that any degree of ordering, from disordered to ordered, can be observed in mullite.

Small‐pore zeolites such as chabazite (CHA) are excellent candidates for the selective separation of CO2; however, the current synthesis involves several steps and the use of organic structure‐directing agent (OSDA), increasing their cost and energy requirements. We report the synthesis of small‐pore zeolite crystals (aluminosilicate) with CHA‐type framework structure by direct synthesis in a colloidal suspension containing a mixture of inorganic cations only (Na+, K+, and Cs+). The location of CO2 molecules in the host structure was revealed by 3D electron diffraction (3D ED). The high sorption capacity for CO2 (3.8 mmol g−1 at 121 kPa), structural stability and regenerability of the discreate CHA zeolite nanocrystals is maintained for 10 consecutive cycles without any visible degradation. The CHA zeolite (Si:Al=2) reaches an almost perfect CO2 storage capacity (8 CO2 per unit cell) and high selectivity (no CH4 was adsorbed).

A mullite single crystal with composition AlSiO exhibiting sharp satellite reflections was investigated by means of X-ray diffraction. For the refinement of a superspace model in the superspace group Pbam(α0½)0ss different scale factors for main and satellite reflections were used in order to describe an ordered mullite structure embedded in a disordered polymorph. The ordered fraction of the mullite sample exhibits a completely ordered vacancy distribution and can be described as a block structure of vacancy blocks (VBs) that alternate with vacancy-free blocks (VFBs) along a and c. The incommensurate nature of mullite originates from a modulation of the block size, which depends on the composition. The displacive modulation is analyzed with respect to the vacancy distribution and a possible Al/Si ordering scheme is derived, although the measurement itself is not sensitive to the Al/Si distribution. An idealized, commensurate approximation for 2/1 mullite is also presented. Comparison of the ordered superspace model with different preceding models reconciles many key investigations of the last decades with partly contradicting conclusions, where mullite was usually treated as either ordered or disordered instead of considering simultaneously different states of order.

Multiple scattering in 3D electron diffraction (3D ED) experiments is responsible for deviations of diffracted intensities from intensities expected from kinematical diffraction theory [1]. Though this is usually considered a disturbing factor in routine structure determinations, these deviations also contain valuable information on the absolute structure [2]. Analysing 3D ED measurements from different laboratories around the world, we demonstrate that the absolute structure of single submicrometric crystals can be reliably and easily determined in a routine way if dynamical diffraction effects are incorporated in the refinement of the structure model.

The properties and crystal structure of two new polymorphs of [Fe(tvp) 2 (NCS) 2 ]•tvp [tvp = trans-(4,4′-vinylenedipyridine)] are investigated. Despite being unusual in metal−organic frameworks (MOFs), one of them shows a commensurate modulation with q = (1/4, 0, −1/4) at room temperature and an unmodulated triclinic structure at lower temperatures that requires a noticeable reconstruction of the H-bond schema. Magnetically, it consists of weakly interacting Fe II zigzag chains. The second compound does not show any structural instability, and the distribution of the almost isolated magnetic ions is square planar. The refined structure models are compared applying fully the superspace approach and group theoretical tools. The structural differences are deeply discussed in terms of host−host and host− guest interactions. Unexpectedly, none of the polymorphs exhibit spin crossover, although they seem to fulfill the structural requirements derived from a thorough comparison with a large family of Fe(NCS) 2 -based MOFs. The aim of this study is to understand the mechanisms enabling or blocking the cooperativity needed for a spin crossover phase transition. They seem to be more related to steric effects than to a delicate balance between elastic and magnetic interactions. In particular, a low compactness of the high-spin state structure appears as a necessary condition for spin crossover to occur.