Synthesis, crystal structure and Hirshfeld surface analysis of dimethyl 3-(3-bromophenyl)-6-methyl-7-oxo-3,5,6,7-tetrahydropyrazolo[1,2-a]pyrazole-1,2-dicarboxylate

The title compound, C17H17BrN2O5, resulted from the 1,3-dipolar cycloaddition reaction between dimethyl acetylenedicarboxylate and (3-bromobenzylidene)-4-methyl-5-oxopyrazolidin-2-ium-1-ide in CHCl3. The dihedral angle between the pyrazole rings (all atoms) is 32.91 (10)°; the oxo-pyrazole ring displays an envelope conformation whereas the other pyrazole ring adopts a twisted conformation. The bromophenyl ring subtends a dihedral angle of 88.95 (9)° with the mean plane of its attached pyrazole ring. In the crystal, the molecules are linked by C—H...O hydrogen bonds and aromatic π–π interactions with an inter-centroid distance of 3.8369 (10) Å. The Hirshfeld surface analysis and fingerprint plots reveal that the molecular packing is governed by H...H (37.1%), O...H/H...O (31.3%), Br...H/H...Br (13.5%) and C...H/H...C (10.6%) contacts. The energy framework indicates that dispersion energy is the major contributor to the molecular packing.

Synthesis and crystal structure of (E)-2-benzyl-1,3-diphenylisothiouronium iodide

In the title molecular salt, C20H19N2S+·I−, prepared by the reaction of 1,3-diphenylthiourea and benzyl iodide, the C—S—C thioether bond angle is 101.66 (9)° and electrons are delocalized over the N+= C—N skeleton. The dihedral angle between the aromatic rings attached to the N atoms is 40.60 (9)°. In the crystal, N—H...I hydrogen bonds link the components into [100] chains.

An Atomistic-Based Nonlinear Plate Theory for Hexagonal Boron Nitride

Through the continuity of the DREIDING force field, we propose, for the first time, the finite-deformation plate theory for the single-layer hexagonal boron nitride (h-BN) to clarify the atomic source of the structure against deformations. Divergent from the classical Föppl-von Karman plate theory, our new theory shows that h-BN’s two in-plane mechanical parameters are independent of two out-of-plane mechanical parameters. The new theory reveals the relationships between the h-BN’s elastic rigidities and the atomic force field: (1) two in-plane elastic rigidities come from the bond stretching and the bond angle bending; (2) the bending rigidity comes from the inversion angle and the dihedral angle torsion; (3) the Gaussian rigidity only comes from the dihedral angle torsion. Mechanical parameters obtained by our theory align with atomic calculations. The new theory proves that two four-body terms in the DREIDING force field are necessary to model the h-BN’s mechanical properties. Overall, our theory establishes a foundation to apply the classical plate theory on the h-BN, and the approach in this paper is heuristic in modelling the mechanical properties of the other two-dimensional nanostructures.

Crystal structure of 1,1′-(pyridine-2,6-diyl)bis[N-(pyridin-2-ylmethyl)methanaminium] dichloride dihydrate

In the title compound, C19H23N5 2+·2Cl−·2H2O, the two pyridine side arms are not coplanar, with the terminal pyridine rings subtending a dihedral angle of 26.45 (6)°. In the crystal, hydrogen bonds, intermolecular C—H...Cl contacts and a weak C—H...O interaction connect the molecule with neighbouring chloride counter-anions and lattice water molecules. The crystal packing also features by π–π interactions with centroid-centroid distances of 3.4864 (12) and 3.5129 (13) Å.

Synthesis and crystal structure of racemic (R*,R*)-2,2′-(1,4-phenylene)bis(3-phenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one)

In the racemic title compound, C26H24N2O2S2, one of the thiazine rings shows a twisted boat conformation (Q = 0.743 Å, θ = 92.1°) and the other a half-chair puckering (Q = 0.669 Å, θ = 54.3°). The terminal phenyl rings are almost parallel to each other [dihedral angle 21.71 (10)°]. Both of these rings are orthogonal to the central phenyl ring, subtending a dihedral angle of about 78° in each case. The extended structure is consolidated by C—H...O and C—H...S hydrogen bonds as well as aromatic ring interactions of parallel-displaced and T-type. The molecule has approximate C2 local symmetry but this is not carried over to its three-dimensional structure or the intermolecular interactions.

Synthesis, crystal structure and Hirshfeld surface analysis of 5-cyclopropyl-N-(2-hydroxyethyl)-1-(4-methylphenyl)-1H-1,2,3-triazole-4-carboxamide

The title compound, C15H18N4O2, was obtained via a two-step synthesis (Dimroth reaction and amidation) for anticancer activity screening and was selected from a 1H-1,2,3-triazole-4-carboxamide library. The cyclopropyl ring is oriented almost perpendicular to the benzene ring [dihedral angle = 87.9 (1)°], while the dihedral angle between the mean plane of the cyclopropyl ring and that of the triazole ring is 55.6 (1)°. In the crystal, the molecules are linked by O—H...O and C—H...N interactions into infinite ribbons propagating in the [001] direction, which are interconnected by weak C—H...O interactions into layers. The intermolecular interactions were characterized via Hirshfeld surface analysis, which indicated that the largest fingerprint contact percentages are H...H (55.5%), N...H/H...N (15.4%), C...H/H...C (13.2%) and O...H/H...O (12.9%).

Ethyl 2-[(E)-({2,4-dimethoxy-6-[2-(4-methoxyphenyl)ethenyl]benzylidene}amino)oxy]acetate

In the title compound, C22H25NO6, the C=C double bond linking the benzene rings adopts an E configuration and the dihedral angle between the rings is 47.1 (2)°. The oxime unit contains a C=N double bond, which also has an E configuration. In the crystal, pairs of C—H...N hydrogen bonds generate inversion dimers and weak C—H...O interactions link the dimers into chains propagating along the b-axis direction.