New solvates and a salt of the anti-HIV compound etravirine

Four new solvates of the anti-HIV compound etravirine [systematic name: 4-({6-amino-5-bromo-2-[(4-cyanophenyl)amino]pyrimidin-4-yl}oxy)-3,5-dimethylbenzonitrile, C20H15BrN6O] with dimethyl sulfoxide (C2H6OS, two distinct monosolvates), 1,4-dioxane (C4H8O2, the 0.75-solvate) and N,N-dimethylacetamide (C4H9NO, the monosolvate), which exhibit conversion to the same anhydrous etravirine phase upon desolvation, and a stable etravirinium oxalate salt {6-amino-5-bromo-4-(4-cyano-2,6-dimethylphenoxy)-2-[(4-cyanophenyl)amino]pyrimidin-1-ium hemioxalate, C20H16BrN6O+·0.5C2O4 2−} were obtained. The crystal structures were solved by single-crystal X-ray diffraction and analyzed by powder X-ray diffraction, and the intermolecular interactions were explored by Hirshfeld surface analysis. Lattice energies were evaluated using the atom–atom force field Coulomb–London–Pauli (AA CLP) approximation, which distributes the total energy as four separate contributions: Coulombic, polarization, dispersion and repulsion. The formation of the solvates and the oxalate salt was further characterized by thermal analysis and IR spectroscopy.

Liquid water contains the building blocks of diverse ice phases

Water molecules can arrange into a liquid with complex hydrogen-bond networks and at least 17 experimentally confirmed ice phases with enormous structural diversity. It remains a puzzle how or whether this multitude of arrangements in different phases of water are related. Here we investigate the structural similarities between liquid water and a comprehensive set of 54 ice phases in simulations, by directly comparing their local environments using general atomic descriptors, and also by demonstrating that a machine-learning potential trained on liquid water alone can predict the densities, lattice energies, and vibrational properties of the ices. The finding that the local environments characterising the different ice phases are found in water sheds light on the phase behavior of water, and rationalizes the transferability of water models between different phases.

Stability Study of Four Layer Aurivillius Oxide of AxBi4-xTi4O15 (A = Ca, Sr, Ba): Atomistic Simulation

Aurivillius is bismuth layered structure ferroelectrics that can be applied as memory, sensor, and catalyst. This research aimed to study the stability of AxBi4-xTi4O15 Aurivillius (A = Ca, Sr, and Ba). Dopants (A) partially substitute Bi at the sites of Bi(1) and Bi(2) of the perovskite layer. This research method is an atomistic simulation using by the GULP code. Simulations were carried out by means of AxBi4-xTi4O15 geometry optimization at constant pressure, using the Buckingham potential. The results showed that the increase in the concentration of dopants substituting Bi accompanied by an increase in lattice energies. The most stable Aurivillius was CaxBi4-xTi4O15 (x = 16.3%) carried out by Bi substitution at Bi(2) site, with lattice energy, -1668.227 eV. Aurivillius stability decreases by increasing the size of the dopant. The maximum concentration number of A dopant substituting Bi was discussed.

The synthesis, crystal structure and Hirshfeld analysis of 4-(3,4-dimethylanilino)-N-(3,4-dimethylphenyl)quinoline-3-carboxamide

The structure of the title quinoline carboxamide derivative, C26H25N3O, is described. The quinoline moiety is not planar as a result of a slight puckering of the pyridine ring. The secondary amine has a slightly pyramidal geometry, certainly not planar. Both intra- and intermolecular hydrogen bonds are present. Hirshfeld surface analysis and lattice energies were used to investigate the intermolecular interactions.

Organoelement Compounds Crystallized In Situ: Weak Intermolecular Interactions and Lattice Energies

The in situ crystallization is the most suitable way to obtain a crystal of a low-melting-point compound to determine its structure via X-Ray diffraction. Herein, the intermolecular interactions and some crystal properties of low-melting-point organoelement compounds (lattice energies, melting points, etc.) are discussed. The discussed structures were divided into two groups: organoelement compounds of groups 13–16 and organofluorine compounds with other halogen atoms (Cl, Br, I). The most of intermolecular interactions in the first group are represented by weak hydrogen bonds and H···H interactions. The crystal packing of the second group of compounds is stabilized by various interactions between halogen atoms in conjunction with hydrogen bonding and stacking interactions. The data on intermolecular interactions from the analysis of crystal packing allowed us to obtain correlations between lattice energies and Hirshfeld molecular surface areas, molecular volumes, and melting points.

Intermolecular Interactions in Molecular Organic Crystals upon Relaxation of Lattice Parameters

Crystal structure prediction is based on the assumption that the most thermodynamically stable structure will crystallize first. The existence of other structures such as polymorphs or from counterenantiomers requires an accurate calculation of the electronic energy. Using atom-centered Gaussian basis functions in periodic Density Functional Theory (DFT) calculations in Turbomole, the performance of two dispersion-corrected functionals, PBE-D3 and B97-D, is assessed for molecular organic crystals of the X23 benchmark set. B97-D shows a MAE (mean absolute error) of 4 kJ/mol, compared to 9 kJ/mol for PBE-D3. A strategy for the convergence of lattice energies towards the basis set limit is outlined. A simultaneous minimization of molecular structures and lattice parameters shows that both methods are able to reproduce experimental unit cell parameters to within 4–5%. Calculated lattice energies, however, deviate slightly more from the experiment, i.e., by 0.4 kJ/mol after unit cell optimization for PBE-D3 and 0.5 kJ/mol for B97-D. The accuracy of the calculated lattice energies compared to the experimental values demonstrates the ability of current DFT methods to assist in the quest for possible polymorphs and enantioselective crystallization processes.

Crystal and molecular structures of boldenone and four boldenone steroid esters

Androsta-1,4-dien-17β-ol-3-one, also known as boldenone, is an anabolic-androgenic steroid derived from testosterone. The crystal structures of boldenone base, boldenone acetate, boldenone propionate, boldenone cypionate and a boldenone acetate polymorph obtained by high throughput screening were investigated. Hirshfeld surfaces and fingerprint plots breakdown revealed that the molecular packing in the crystals are driven by dominant H⋯H intermolecular contacts, followed by O⋯H/H⋯O contacts and to a lesser degree C⋯H/H⋯C contacts. The steroid skeleton rings, for all the reported compounds, adopt the following conformation: planar in A, chair in B and C, whereas C(13) envelope conformations are found for the five-membered D rings. The total lattice energies were calculated as a sum of four terms (Coulombic, polarization, dispersion, repulsion).