Journal of Chemical Crystallography最新文献

We have obtained previously known and new 4,8-C-substituted hexahydroquinazolincyanamides by two-component condensation of 2,6-diaryl(heteroaryl)methylidenecyclohexanones with the same or different terminal substituents with N-cyanoguanidine according to a modified procedure under conditions of basic catalysis. We have grown a singlecrystal of one of the representatives of the series –N-(8-benzylidene-4-phenylhexahydroquinazolin-2(1H)-ylidene)cyanamideby crystallization from a saturated solution of acetonitrile and carried out its X-ray diffraction study. The structure of N-(8-benzylidene-4-phenylhexahydroquinazolin-2(1H)-ylidene)cyanamide, C₂₂H₂₀N₄, has orthorhombic (P2₁2₁2₁) symmetry. The molecule is built from fused non-planar cyclohexene and tetrahydropyrimidine rings. The cyclohexene ring is in the half-chair conformation, while the tetrahydropyrimidine ring adopts the ‘C-envelope’ conformation. The crystal packing of the compound is an alternating layered structure. The mutual arrangement of molecules promotes the formation of intermolecular hydrogen bonds (IMH) between the H1 hydrogen atoms of the quinazoline ring and the N4 nitrogen atoms of the nitrile group. Non-planar C–H···π interactions are observed in the crystal as well. The compound is in the E,E-configuration. The calculation and analysis of Hirschfeld surfaces demonstrated the presence of hydrogen bonds, different in energy, and C–H···π interactions between benzene rings and protons of other benzene rings of neighbouring molecules in both the benzylidene and phenyl substituents.

Graphical Abstract

X-ray diffraction analysis of hexahydroquinazolincyanamide showed that there are intermolecular hydrogen bonds with the hydrogen atoms of the quinazoline ring and the nitrogen atoms of the nitrile and imine groups. An assessment of the intermolecular stacking interaction is given.

The crystal structure of [Cu₃(C₇H₅O₃)₄(C₂₀H₂₀NO₅)₂(H₂O)₂]·2(H₂O) (1) and analysis of temperature and field dependence of magnetic susceptibility is reported in this work. The structure of 1 is composed of trinuclear complex units and water molecules. The middle copper atom occupies the center of symmetry. N, O-bonded (6,7-dimethoxy-isoquinolin-1-yl)-(3,4-di­methoxy-phenyl)-methanolato ligands, 2-hydroxybenzoates with bridging carboxylic groups, and oxo-bridged water molecules connect the middle Cu(II) atom with the terminal copper atoms. Two 2-hydroxybenzoates coordinate the terminal copper atoms via one carboxylic oxygen and an O atom of the hydroxyl group. The analysis of copper coordination by bond-valence sum approach and relevant structural correlation is consistent with hexacoordinated Cu(II) centers. Cu···Cu separation is 3.0269(3) Å. The magnetism of 1 shows a strong ferromagnetic interaction between the neighboring metallic centers accompanied by very weak antiferromagnetic intermolecular interactions. The complex units are mutually held by π···π stack interactions of 2-hydroxybenzoates and hydrogen bonds.

Graphical Abstract

A new N,O bonded ligands, (R, S)-[(6,7-dimethoxy-isoquinolin-1-yl)-(3,4-dimethoxy-phenyl)-methanolate] coordinate the terminal atoms of the trinuclear copper(II) complex.

Previously unknown crystal structure of a copper(II) tetrafluoroborate hexahydrate salt was determined using single crystal X-ray diffraction. The unit cell parameters were determined at different temperatures (90, 150 and 270 K). The structure is isotypical with copper(II) perchlorate hexahydrate. The Raman spectrum was also recorded and discussed.

Graphical Abstract

The K.P.I. coefficient (78.0) and the FUV index (256.21 Å³) indicating very effective packing of the ions in the discussed structure, whereas the β angle is very close to the 90° and, in this way, the crystal could undergo a monoclinic (to ) orthorhombic phase transition at some lower temperatures.

A cocrystal of 2,3,5,6-tetramethylpyrazine and 1,3,4,5-tetrabromo-2,6-difluorobenzene has been prepared and its crystal structure has been determined via single-crystal X-ray diffraction. Infinite chains of roughly coplanar donor and acceptor molecules are held together by two crystallographically distinct and highly linear Br···N halogen bonds. Four further crystallographically distinct Br···Br halogen bonds are also observed. Each of the two Br atoms in the 3 and 5 positions on the benzene ring acts simultaneously as a halogen bond donor and acceptor to two additional bromines on two neighbouring 1,3,4,5-tetrabromo-2,6-difluorobenzene molecules. These halogen bonds are also classified as type II halogen-halogen contacts. As a result of these contacts, a staggered herringbone arrangement of the infinite chains results. These structural features are shown to be consistent with computed molecular electrostatic potential and Hirshfeld surfaces. The insights gained through this analysis imply that additional systematic variations in the substitution motifs of aromatic halogen bond donors may lead to new structures and properties. As part of this work, a single-crystal X-ray structure of 1,3,4,5-tetrabromo-2,6-difluorobenzene of moderate quality is also reported.

Graphical Abstract

The single-crystal X-ray diffraction structure of a 1:1 cocrystal of 2,3,5,6-tetramethylpyrazine and 1,3,4,5-tetrabromo-2,6-difluorobenzene is reported. Bromine-nitrogen halogen bonds link the two types of molecules together, forming infinite chains. Bromine-bromine halogen bonds (type II contacts) between aromatic molecules stabilize a herringbone-like packing arrangement.

A vanadium(IV) Schiff base complex derived from salicylaldehyde and L-alanine with phenanthroline as co-ligand viz. [V^IVO(salala)(phen)]1.66H₂O (where salala = Schiff base derived from salicylaldehyde and L-alanine, phen = 1,10-phenanthroline) have been synthesized and its structure determined by single crystal X-ray diffraction. The crystal lattice parameters of the complex was determined by single crystal X-ray diffraction with lattice parameters, a = 18.4361 [5] Å, b = 22.4926 [6] Å, c = 12.4035 [6] Å, β = 126.904 [1]°, C2 space group, Z = 2. In the crystal, the V(IV) ions are in distorted octahedral geometry, coordinated to two oxygen atoms and one nitrogen atom of Schiff base ligand and two phenanthroline nitrogen atoms. The π···π stacking interactions as well as C–H···O hydrogen bonds were found to play an important role in the self-assembly of the complex molecules. The non-covalent interactions of the complex were further evaluated by Hirshfeld Surface Analysis. Spectroscopic characterization of the complex by Infrared and UV–visible spectroscopic techniques is also reported.

Graphical Abstract

Crystal structure of a vanadium(IV) Schiff base complex derived from salicylaldehyde and L-alanine with phenanthroline as co-ligand have been determined by single crystal X-ray diffraction and non-covalent interactions between the complex molecules studied by Hirshfeld surface analysis.

A new aqua-tricaesium-sodium polymetavanadate compound, [Cs₃Na(VO₃)₄(H₂O)] (1), was synthesized by reacting caesium chloride and sodium metavanadate at ambient pH. The structure was characterized and identified using single-crystal X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, and energy dispersive X-ray analysis (EDS). Compound (1) crystallizes in an orthorhombic system with a Pnma space group, and cell parameters a = 11.6554(4), b = 8.3408(2), c = 16.1121(5). Vanadium has tetrahedral coordination connected to the next vanadium atom through an oxygen bridge. The infinite zigzag metavanadate chains formed by corner-sharing VO₄ tetrahedral constitute a1D building block. The chains were laterally connected through Cs, Na, and H₂O. This connectivity generates continuous 2D layers within the ab plane. The photocatalytic performance of (1) was evaluated by measuring the degradation of methylene blue under visible light. The results confirmed the efficiency of the photocatalytic activity because of the narrowed bandgap energy of 2.18 eV, and 85% degradation rate, making it suitable for absorbing visible light.

Graphical Abstract

The paper reports the synthesise and characterization of a new isopolyvanadate compound, [Cs₃Na(VO₃)₄H₂O], which contains vanadim in the five oxidation state with tetrahedral coordination.  It forms metavanadate chains interconnected by caesium and sodium cations. The photocatalytic activity was tested by degrading methylen blue under visible light irradiation. The results showed decent activity attributed to the narrowed bandgap energy of 2.18 eV.

Reaction of 4,6-dinitroresorcinol (1) and the nitrogen base 1,4-diazabicyclo[2·2·2]octane (2) affords the 1:2 salt and proton-transfer compound 1,4-diazabicyclo[2·2·2]octane-1,4-diium bis(5-hydroxy-2,4-dinitrophenolate) (3). Compound 3 crystallizes in the triclinic crystal system (space group P-1) with a = 8.3242(5) Å, b = 11.9915(7) Å, c = 12.4595(7) Å, α = 116.282(2)°, β = 100.576(3)°, γ = 101.051(2)°, 1042.30(11) ų and Z = 2. The dication 2-({text{H}}_{2}^{2+}) forms charge assisted donating bifurcated N⁺−H⋅⋅⋅O⁻ hydrogen bonds to the phenolate moieties of two monoanions of 1. The latter exhibit an intramolecular O−H⋅⋅⋅O hydrogen bond between the hydroxy group and the nitro group in ortho position. The crystal structure of 3 features pseudo B-centering of the lattice, which relates the two crystallographically distinct monoanions of 1 by a pseudo translation. The possible B-centring is broken by the ethylene groups of 2-H₂²⁺, which are related in neighbouring molecules by centres of symmetry.

Graphical Abstract

The 1:2 proton-transfer compound 1,4-diazabicyclo[2.2.2]octane-1,4-diium bis(5-hydroxy-2,4-dinitrophenolate) features pseudo B-centering of the lattice.

The crystal structure of tetrachloroferrate(III) complex with methylene blue, [Mb]⁺[FeCl₄]⁻ (where [Mb]⁺ methylthioninium or 3,7-bis(dimethylamino)-phenothiazine-5-ium cation), has been prepared by mechanochemical way and studied by the single crystal X-ray crystallography. The crystal structure of title compound is built from by [FeCl₄]⁻ tetrahedral ion and planar [Mb]⁺ counter ions. The [Mb]⁺ cation is linked in the 3D network by the C–H···Cl hydrogen bonds and is stacked in an antiparallel fashion with the sulfur atom disposed alternatively on an opposite sides of the stacking. The interplanar distance between two neighboring aromatic cycles is 3.431 Å, and a centroids–centroids distance between thiazine rings is 3.975 Å. Dihedral angle between aromatic rings is 1.6°. Intermolecular short contacts were analyzed by 3D Hirshfeld surfaces method and 2D fingerprint plots. Intermolecular interaction energy between two neighboring Mb⁺ cation pair was calculated by using of CE-B3LYP/6-31G(d,p) theoretical level.

Graphical Abstract

The π···π stacking interactions were found plays an important role in the crystal structure formation of the FeCl₃ complex with methylene blue, and calculation by the CrystalExlorer17.5 program indicates that π···π interaction energy between two neighboring methylene blue cations is −33.5 kJ/mol.

Copper(II) and zinc(II) complexes, [Cu(esct)(4-pico)] (1), [Zn(esct)(5,5′-dmbipy)]·H₂O (2), [Cu(esct)(5,5′-dmbipy)] (3), (where H₂esct = 3-ethoxysalicylaldehye-N⁴-cyclohexylthiosemicarbazone) were synthesized by reacting copper acetate/zinc acetate with the thiosemicarbazone derivative (H₂esct) along with heterocyclic bases. The thiosemicarbazone forms doubly deprotonated anions in all the complexes to coordinate via thiolate S, azomethine N and phenolate O atoms. The complexes were characterized by various spectroscopic techniques like infrared, UV–vis, ¹H NMR and EPR spectra. The single crystal XRD studies confirmed the structures. All the three complexes got crystallized in triclinic space group P (overline{1 }.) Complexes are found to have four, five and six coordination around the metal center. The importance of van der Waals interactions in them is explained by Hirshfeld surface analysis. We have used Density Functional Theory (DFT) methods and optimized ground states of the studied complexes using the Gaussian 09 package. Electrostatic potential plots of complexes were investigated. Further, docking studies were carried out with various Epidermal Growth Factor Receptor (EGFR) enzymes.

Graphical Abstract

Three mixed ligand Cu(II) and Zn(II) complexes prepared from a thiosemicarbazone showed interesting geometries and structures

A new complex compound, catena-triglycinium-µ-chlorido-tetrachloridocuprate(II) glycine co-crystal (or glycine-triglycinium pentachlorocuprate), {(C₂H₆NO₂)₃CuCl₅·(C₂H₅NO₂)}_n, was synthesized and studied by single crystal X-ray diffraction (SC XRD) and mid-range infrared spectroscopy. The compound crystallizes in a non-centrosymmetric triclinic P1 space group with lattice parameters a = 5.1277(2) Å, b = 9.1412(6) Å, c = 12.2023(5) Å, α = 101.407(4)°, β = 97.460(3)°, γ = 105.832(4)°, Z = 1. The unit cell contains four glycine ions—three glycinium cations and single zwitter-ion—linked through hydrogen bonds network. The anionic part of the compound is presented by infinite chains [CuCl₆]_n of distorted (elongated) octahedra, connected by vertices and alternating direction of elongated axis. Positions of hydrogen atoms were refined using geometry optimization via density functional theory (DFT) approach. Thermogravimetric analysis (TGA) showed the title compound to be stable in air atmosphere up to ∼ 388‒393 K and decomposes upon further heating.

Graphical Abstract

Unit cell content of the glycine-triglycinium pentachlorocuprate, determined by the SC XRD analysis