Acta Crystallographica Section C Structural Chemistry最新文献

Two cathinones found on the market for legal highs have been characterized using X-ray crystallography. These are 1-(1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride monohydrate, C₁₅H₂₂NO⁺·Cl^-·H₂O (α-PVP·HCl·H₂O), with erythritol [(2R,3S)-butane-1,2,3,4-tetrol, C₄H₁₀O₄] as diluent in the sample, and 1-(2-oxo-1,2-diphenylethyl)pyrrolidin-1-ium chloride, C₁₈H₁₈NO⁺·Cl^- (α-D2PV·HCl or A-D2PV·HCl). The intermolecular interactions occurring in the various crystal structures of these compounds have been described. The two arene rings of α-D2PV participate in the formation of π-π bonds (with parallel-displaced geometries of the π-π interactions). In addition, one of the rings forms a C-H...π interaction with an arene ring participating in an adjacent π-π bond, resulting in a linear arrangement of the molecules in the crystal. In the hydrated α-PVP salt, the molecules form a structure, the so-called `corral', in which two water molecules and two chloride ions are confined. The whole is held together by intermolecular hydrogen bonds. The structure of the chloride salt of α-D2PV described here lacks water molecules, which automatically allows for the formation of other types of intermolecular interactions. This structure was compared with the previously published hydrated form.

Quantitative phase analysis (QPA) by X-ray diffraction is widely used in materials, minerals, metallurgy, etc. But when preferred orientation exists in samples, QPA by single peaks in diffraction patterns will be seriously affected and becomes less exact, for example, for phosphate materials. As an alternative, whole pattern methods (especially the Rietveld method) can be utilized positively and the effect of preferred orientation can be solved mathematically. But application of the Rietveld method generally takes a lot of time, not only in high-accuracy pattern acquisition, but also in continuously refining many parameters for multiple iterative computation, which is not applicable to situations where rapid or automatic QPA is required, such as industrial production, customs inspection, and so on. In this article, a new mathematical method was developed and discussed, and was then reasonably simplified for convenient operation. The simplified method was tested and examined using the N₂H₉PO₄ phase, which can produce preferred orientation easily. The results indicated that the QPA deviation is reduced from about 33% using the single-peak method to less than 1% using the new simplified method. Use of the new method and its simplified version is recommended when preferred orientation exists and rapid or automatic QPA is required.

Motivated by a theoretical prediction of its potential superconductivity under ambient pressure, a novel oxychloride, Sr₃Ni₂O₅Cl₂, was synthesized for the first time. This synthesis utilized a high pressure of 10 GPa at 1673 K. Small single crystals were used to determine the crystal structure and measure the temperature dependence of electrical resistance. The crystal is isostructural with the recently discovered superconductor La₃Ni₂O₇, in line with theoretical expectation.

A number of piperazine derivatives of hydantoin display high affinity for α₁-adrenoreceptors and antagonistic properties, which make them potent hypotensive agents. In order to study the correlations between affinity for α₁-adrenoreceptors and molecular structures, the crystal structures of six piperazine derivatives of 5,5-dimethylhydantoin were determined by X-ray diffraction, namely, 4-(3-{3-[(2,4-dichlorophenyl)methyl]-5,5-dimethyl-2,4-dioxoimidazolidin-1-yl}-2-hydroxypropyl)-1-phenylpiperazine-1,4-diium dichloride monohydrate ethyl acetate hemisolvate, C₂₅H₃₂Cl₂N₄O₃²⁺·2Cl^-·H₂O·0.5C₄H₈O₂ (1), 4-(2-cyanophenyl)-1-(3-{3-[(2,4-dichlorophenyl)methyl]-5,5-dimethyl-2,4-dioxoimidazolidin-1-yl}-2-hydroxypropyl)piperazin-1-ium chloride acetonitrile monosolvate, C₂₆H₃₀Cl₂N₅O₃⁺·Cl^-·C₂H₃N (2), 1-(3-{3-[(2,4-dichlorophenyl)methyl]-5,5-dimethyl-2,4-dioxoimidazolidin-1-yl}-2-hydroxypropyl)-4-(3,4-dimethylphenyl)piperazin-1-ium chloride, C₂₇H₃₅Cl₂N₄O₃⁺·Cl^- (3), 1-(3-{3-[(2,4-dichlorophenyl)methyl]-5,5-dimethyl-2,4-dioxoimidazolidin-1-yl}-2-hydroxypropyl)-4-(3-methoxyphenyl)piperazin-1-ium chloride, C₂₆H₃₃Cl₂N₄O₄⁺·Cl^- (4), 4-(2,3-dichlorophenyl)-1-(3-{3-[(2,4-dichlorophenyl)methyl]-5,5-dimethyl-2,4-dioxoimidazolidin-1-yl}-2-hydroxypropyl)piperazin-1-ium chloride 0.2-hydrate, C₂₅H₂₉Cl₄N₄O₃⁺·Cl^-·0.2H₂O (5), and 3-[(2,4-dichlorophenyl)methyl]-1-{3-[4-(3,4-dichlorophenyl)piperazin-1-yl]-2-hydroxypropyl}-5,5-dimethylimidazolidine-2,4-dione, C₂₅H₂₈Cl₄N₄O₃ (6). The compounds crystallize in the centrosymmetric triclinic space group, except for 2, which crystallizes in the monoclinic space group P2₁/c. For all six compounds, one molecule is observed in the asymmetric unit. The molecule of 1 is doubly protonated at both N atoms of the piperazine ring, whereas 2, 3, 4 and 5 are only protonated at one ring N atom. The protonated N atoms are engaged in charge-assisted hydrogen bonds with the chloride anions, and in 1 the N atom interacts with the chloride anion via the water molecule. The crystal packing in the protonated molecules (1-5) is in each case dominated by a network of N-H⁺...Cl^-, O-H...Cl^- and C-H...Cl^- hydrogen bonds, while in the base molecule of 6, O-H...O hydrogen bonds dominate.

The synthesis, crystal structure, and [2+2] cycloaddition photoreactivity of a halogen-bonded mixed cocrystal is reported. The cocrystal solid solution contains two isosteric donors, namely, 1,4-diiodoperchlorobenzene (C₆I₂Cl₄) and iodoperchlorobenzene (C₆ICl₅), along with trans-1,2-bis(pyridin-4-yl)ethylene (BPE, C₁₂H₁₀N₂) which behaves as a ditopic reactant molecule. The mixed cocrystal, namely, (C₆I₂Cl₄)_0.75·(C₆ICl₅)_0.25·(BPE), is achieved since both halogen-bond donors are similar in shape and are interchangeable at equivalent crystallographic positions. The combination of I...N and Cl...N halogen bonds generates one-dimensional chains that engage in homogeneous π-stacks, thereby positioning a pair of reactant molecules in a suitable location to photoreact. Notably, the overall yield for the solid-state photoreaction is influenced by the initial molar ratio of the isosteric halogen-bond donors within the mixed cocrystal.

To date there are very few examples of crystallographically well-documented racemic mimics. The original discovery of this class of crystals occurred at a time when crystallography was in its infancy, data collection and processing were tedious and limited by X-ray equipment, and computing power was indeed limited. Therefore, this interesting class of crystalline molecules, potentially having useful biological uses, is today one of those scientific orphans largely ignored in the crystallographic realm. As proof of this, to date, you cannot systematically search for this class in databases. Thus, for the time being, there are few satisfactory examples of high-quality crystal structures of both members of such pairs which have been highlighted in the literature. Finally, being largely undocumented, there are no useful clues to guide you as to how to guess the classes of compounds likely to produce such pairs. The question then is, how do we go about searching for potential cases of such crystallization modes using information already in print? Herein, we provide some suggestions we believe are useful, and to the extent possible with such data, to illustrate the possibilities offered by such an approach.

Three multicomponent systems, namely, 2,4-diamino-6-phenyl-1,3,5-triazine-nicotinic acid (DAPT-NA), C₉H₉N₅·C₆H₅NO₂, (I), 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium hydrogen malonate (DAPT-MMA), C₉H₁₀N₅⁺·C₃H₃O₄^-, (II), and 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium hydrogen (+)-dibenzoyl-D-tartarate (DAPT-DBTA), C₉H₁₀N₅⁺·C₁₈H₁₃O₈^-, (III), have been synthesized and characterized via single-crystal X-ray diffraction, and their supramolecular interactions have been analysed. The formation of cocrystal (I) and salts (II) and (III) was confirmed through the widening of the C-N-C bond angle of the triazine moiety of 2,4-diamino-6-phenyl-1,3,5-triazine and the difference in the C-O bond distances between the carboxyl and carboxylate groups of the respective carboxylic acids. Cocrystal (I) and salt (II) form robust homomeric and heteromeric R₂²(8) ring motifs through primary acid-base interactions and complementary base pairing. In cocrystal (I), the complementary base pair exists as wave-like supramolecular strands, whereas in salt (II), it exists as a discrete pair. Salt (II) exhibits DDDAAD sextuple and DADA quadruple hydrogen-bonded arrays (D is donor and A is acceptor) through acid-base interactions and generates a supramolecular rosette-like architecture. In salt (III), the presence of carboxyl-carboxylate interactions and acid-base interactions led to the development of a supramolecular sheet and tunnel-like architecture. Cocrystal (I) and salt (III) are stabilized through offset aromatic π-π stacking interactions and C-H...π interactions, and salts (II) and (III) are stabilized via weak carbonyl-π and C-H...O hydrogen bonds. Macrocyclic R₁₂¹²(64) and R₃³(24) motifs are present in salts (II) and (III), respectively. Hirshfeld surface analysis of (I)-(III) reinforces the fact that N...H/H...N, O...H/H...O and C...H/H...C interactions contribute to the crystal packing and stability.

The transformation of a thiocarbonyl compound into an alkene by stepwise treatment with a diazo compound and triphenylphosphane is known as Barton-Kellogg olefination. As a model reaction, 4,4'-dimethoxythiobenzophenone and diazocyclohexane were used to prepare [bis(4-methoxyphenyl)methylidene]cyclohexane, C₂₁H₂₄O₂. The crystal structure of the latter, as well as that of the intermediate thiirane, 2,2-bis(4-methoxyphenyl)-1-thiaspiro[2.5]octane, C₂₁H₂₄O₂S, have been determined and their molecular conformations and geometries are generally consistent with those of related structures in the literature. Variations in the influence of four substituents on crowded thiirane rings are minimal and the main differences are noted in the presence of bulky tert-butyl substituents. The conformation of the intermediate thiirane is influenced by weak intramolecular C-H...S interactions. A three-dimensional supramolecular structure of the methylene cyclohexane compound results from the combination of three distinct weak C-H...π interactions. Under similar reaction conditions, 5-phenyl-3H-1,2-dithiole-3-thione has been transformed into 3-[bis(4-methoxyphenyl)methylidene]-5-phenyl-3H-1,2-dithiole, C₂₄H₂₀O₂S₂, by treatment with bis(4-methoxyphenyl)diazomethane. The crystal structure of the 1,2-dithiole product reveals a molecule with an all-trans 2,4-hexadiene core, in which the Csp²-Csp² bond lengths display an alternating character that suggests little delocalization of the double bonds. The 1,2-dithiole ring is nearly planar, with just a slight puckering into an envelope form. Two weak C-H...π and one C-H...O interaction link the molecules into thick two-dimensional supramolecular layers.

Noncovalent interactions have received much attention in the fields of supramolecular chemistry and crystal engineering. Hydrogen bonding and weak interaction forces affect crystal stacking. Crown-ether-based host-guest inclusion compounds with hydrogen bonding and weak intermolecular interaction forces deserve our attention. In addition, Xiong and co-workers have proposed a molecular design strategy of H/F substitution. Based on this H/F substitution strategy, it is possible to develop halogen substitution, also known as the halogenation effect. Here, using benzylamine as an organic parent, the molecular design strategy of the halogenation effect was used. That is, halogen atoms (F, Cl, Br and I) were used to replace H atoms at the para site of the aromatic ring, and four halogenated benzylamine compounds were obtained, namely, 4-fluorobenzylaminium di(methanesulfonyl)amidate-18-crown-6 (1/1), C₇H₉FN⁺·C₂H₆NO₄S₂^-·C₁₂H₂₄O₆ or [(4-FBA)(18-crown-6)][DMSA], 1; 4-chlorobenzylaminium di(methanesulfonyl)amidate-18-crown-6 (1/1), C₇H₉ClN⁺·C₂H₆NO₄S₂^-·C₁₂H₂₄O₆ or [(4-ClBA)(18-crown-6)][DMSA], 2; 4-bromobenzylaminium di(methanesulfonyl)amidate-18-crown-6 (1/1), C₇H₉BrN⁺·C₂H₆NO₄S₂^-·C₁₂H₂₄O₆ or [(4-BrBA)(18-crown-6)][DMSA], 3; and 4-iodobenzylaminium di(methanesulfonyl)amidate-18-crown-6 (1/1), C₇H₉IN⁺·C₂H₆NO₄S₂^-·C₁₂H₂₄O₆ or [(4-IBA)(18-crown-6)][DMSA], 4. Clathrate 1 crystallizes in the space group P2₁, while 2-4 crystallize in the space group P2₁/n. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures.

We report the preparation and crystal structure of potassium hafnium pentafluoride, KHfF₅, obtained by the hydrothermal technique. The compound crystallizes in the orthorhombic noncentrosymmetric space group P2₁2₁2₁, with the unit-cell parameters a = 6.2843 (3), b = 7.8063 (3) and c = 15.8286 (7) Å. Hf atoms are coordinated by eight F atoms, forming square antiprismatic polyhedra. Bonding in pairs, HfF₈ antiprisms are interconnected via common F-atom edges and form a double chain of hafnium polyhedra. A comparison of the structure of KHfF₅ with other complex fluorides of alkali metals and hafnium, zirconium or terbium(IV) revealed that this compound has no isostructural analogue among the known phases of general composition M^IM^IVF_5.