Using a list of compatible hydrate/anhydrate pairs prepared by van de Streek and Motherwell [CrystEngComm (2007), 9, 55-64], we have examined the effective volume per water of crystallization for 179 pairs of organic solids using current data from the Cambridge Crystallographic Structural Database (CSD). The effective volume is the difference per water molecule between the asymmetric unit volumes of the hydrate and parent anhydrate, and has the mean value 24 Å3. The conformational changes in the reference molecule between the hydrate and its anhydrate are shown in two figures one for a relatively rigid standard organic molecule and (in the supplementary file) one for a more flexible linear molecule. Using data from Nyman and Day [Phys. Chem. Chem. Phys. (2016), 18, 31132-31143], we have also established a generic volumetric coefficient of thermal expansion of organic solids with a value of 147 ± 56 × 10-6 K-1. There is a significant number of outliers to the data, negative, near zero, and large and positive. Some explanation for the existence of these outliers is attempted.Threefold twinning in 1-(R)-1-[(3-oxo-2-isoindolinoyl)methyl]-2-propenyl-5-methyl-2,3-indolinedione, C21H16N2O4, has been reported recently [Trost et al. (2020). Org. Lett. 22, 2584-2589] but the twin characterization was not published. This twinning presents several interesting features. The crystal structure is monoclinic, but its lattice is metrically strongly pseudo-orthorhombic and underpins a strongly pseudo-hexagonal sublattice. Several possible twin laws are compatible with these metric specializations, among which the one found experimentally corresponds to a trichromatic point group. Twinning is by reticular pseudo-merohedry with twin index 2 and zero obliquity but a non-zero twin misfit. The twin lattice coincides with the pseudo-hexagonal sublattice of the individual domain, which justifies the adoption of the unconventional setting B21 of the space group.Most structural (i.e. displacive) modulations make molecules independent that had been related by translation in a phase having a smaller or centered unit cell. In the modulated structure the independent molecules are differentiated by small translations, rotations, and/or conformational changes but an approximate translational relationship is normally retained. A program has been written to identify such pseudotranslations because they can be difficult to find by eye and because they combine with each other and with lattice translations in ways that can be confusing. To characterize the pseudotranslations the program calculates their fractional translational, orientational, and conformational components as well as several quality indicators. While many pseudotranslations are obvious, others are borderline; setting tolerances for identifying a pseudotranslation proved difficult. Defaults were chosen to reproduce experience-based judgment but they can be varied in the program input. The program was run for organic and for metallo-organic structures with R ≤ 0.075 in the 2019 release of the Cambridge Structural Database. The frequency of pseudotranslations increases with Z' and is approximately 50% for Z' > 4. Some structures were found in which an identified pseudotranslation cannot correspond to a modulation. These include structures in which some but not all of the molecules are related by pseudotranslations and structures in which pseudotranslations in different parts of the unit cell have different directions.Most research on polyoxometalates (POMs) has been devoted to synthetic compounds. However, recent mineralogical discoveries of POMs in mineral structures demonstrate their importance in geochemical systems. In total, 15 different types of POM nanoscale-size clusters in minerals are described herein, which occur in 42 different mineral species. The topological diversity of POM clusters in minerals is rather restricted compared to the multitude of moieties reported for synthetic compounds, but the lists of synthetic and natural POMs do not overlap completely. The metal-oxo clusters in the crystal structures of the vanarsite-group minerals ([As3+V4+2V5+10As5+6O51]7-), bouazzerite and whitecapsite ([M3+3Fe7(AsO4)9O8-;n(OH)n]), putnisite ([Cr3+8(OH)16(CO3)8]8-), and ewingite ([(UO2)24(CO3)30O4(OH)12(H2O)8]32-) contain metal-oxo clusters that have no close chemical or topological analogues in synthetic chemistry. The interesting feature of the POM cluster topologies in minerals is the presence of unusual coordination of metal atoms enforced by the topological restraints imposed upon the cluster geometry (the cubic coordination of Fe3+ and Ti4+ ions in arsmirandite and lehmannite, respectively, and the trigonal prismatic coordination of Fe3+ in bouazzerite and whitecapsite). Complexity analysis indicates that ewingite and morrisonite are the first and the second most structurally complex minerals known so far.  https://www.selleckchem.com/peptide/tirzepatide-ly3298176.html  The formation of nanoscale clusters can be viewed as one of the leading mechanisms of generating structural complexity in both minerals and synthetic inorganic crystalline compounds. The discovery of POM minerals is one of the specific landmarks of descriptive mineralogy and mineralogical crystallography of our time.Intermolecular interactions involving the aromatic C-F group in the absence of other strong hydrogen bond acceptors is the theme of this article. Weak interactions involving fluorine are known to generate various supramolecular synthons, thereby altering the crystal structures of small organic molecules. It is demonstrated that the weak interactions involving organic fluorine play a major role in directing crystal packing of highly flexible organic molecules like diphenyl tetrahydroisoquinolines reported herein. The intramolecular C-H...F hydrogen bonds are found to be significant in controlling the molecular conformation in specific cases wheras the intermolecular interactions involving the C-F groups result in a wide range of supramolecular synthons involving C-H...F and C-F...F-C interactions. The interactions are studied computationally to provide insight into their energies and the topology of the interactions is studied using Atoms in Molecules. C-H...F-C interactions are found to be quite stabilizing in nature with the stabilization energy of -13.