Journal of Chemical Crystallography最新文献

A homochiral metal-organic framework, [Ni(D-L)(py)₂(H₂O)₂]_n (1) [D-H₂L = 4,4′-[[(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarbonyl]bis-(azanediyl)]dibenzoic acid], has been successfully synthesized based on D-camphorate-derived enantiopure ligand. 1 was characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Fourier transform infrared spectral analysis (FTIR), thermogravimetric analysis (TGA) and the circular dichroism (CD) spectrum. The experimental results show that 1 features a homochiral triple helix and is formed a 3D supramolecular framework by supramolecular interactions. In addition, the circular dichroism (CD) spectrum verifies the chirality introduction from the ligand to crystal. The successful preparation of the homochiral Ni-MOF provides more possibilities of employing the chiral ligand to produce various chiral MOFs.

Graphical Abstract

A homochiral Ni(II)-MOF 1 was prepared by using D-camphorate-derived enantiopure ligand under solvothermal condition, in which the chirality of 1 was confirmed by the circular dichroism (CD) spectrum

Bis-[2-(3,4-dihydroxyphenyl)-4,5-diphenyl-1H-imidazol-3-ium] Oxalate ethanol solvate crystal has been isolated from slow solvent evaporation method and the structure was characterized by FT-IR, NMR and Single crystal XRD. The compound crystallizes in the triclinic space group P (overline{1 }) with a = 7.7925(16), b = 10.716(3), c = 13.952(3), α = 106.545(5), β = 97.514(5), γ = 110.152(5), V = 1014.0(4) Å3 and Z = 1. The single crystal X-ray data of the compound confirms two proton transfers from an oxalic acid to the pyrimidine-type-nitrogen of two separate imidazole rings. The structure and symmetry of the Imidazolium Oxalate is dictated by N–H⋯O and O–H⋯O hydrogen bonding interactions and are confirmed by hydrogen bonding analysis and hirshfeld surface analysis. The partial double bond character in the imidazolium ring confirms delocalization across the molecular framework. The partial double bond character of the C–O bonds also confirms delocalization in the oxalate anion. The crystal is 3-dimensional structure, with crystal growth in all the crystallographic axis. Computational analysis [DFT, B3LYP/6-311G(d,p)] reveals close correlation of the constrained optimized structure with the experimental data.

Graphical Abstract

Imidazolium oxalate crystal form by the protonation of Imidazole compound and complex formation with oxalate ion.

Three crystalline organic salts (melamine)₂: (itaconic acid): 3H₂O [(Hmem)₂²⁺·(itca²⁻)·(H₂O)₃, itca²⁻ = itaconate] (1), (melamine)₂:(2-bromo-but-2-enedioic acid):DMF:2H₂O [(Hmem⁺)₂·(bbda²⁻)·DMF·(H₂O)₂, bbda²⁻ = 2-bromo-but-2-enedioate] (2) and (melamine):(α-ketoglutaric acid) [(Hmem⁺)·(Hketglua⁻), Hketglua⁻ = hydrogen α-ketoglutarate] (3) were featured by X-ray diffraction analysis, IR, mp, and elemental analysis. Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis. All salts involve extensive N–H···OH-bonds as well as other non-covalent associations. The melamine polymers/dimers were set up at 1–2/3 by the pair of complmentary N–H···NH-bonds. The role of these non-covalent interactions in the crystal packing is ascertained. These weak interactions combined, all salts exhibited 3D framework motifs.

Graphical Abstract

The crystal structures of the salts from melamine, itaconic acid, 2-bromo-but-2-enedioic acid and α-ketoglutaric acid are predominantly stabilized by the classical hydrogen bonds as well as CH2···O, CH3···O, Br···Br, C···C, O···C, and π···π interactions.

Measurement of the unit cell of (R)-BINOL over a 200° temperature range (300–100 K) reveals an anisotropic contraction where the c-axis contracts ca. 2.3% compared to a ca. 0.45% contraction of the a and b axes, a ca. six-fold difference in linear thermal expansion coefficient. This contraction corresponds to a decrease in the helical pitch of the 3₁ screw axis in the [001] direction. The anisotropic nature of the contraction is rationalised by a thorough analysis of intermolecular contacts within the crystal and their impact on the conformation of the molecule and crystal packing.

Graphical Abstract

The crystal structure of (R)-BINOL exhibits a pronounced anisotropic thermal expansion.

A chelating N-heterocyclic carbene palladium complex (3) containing N-(3-bromopropyl)-N’-thioether di-functionalized imidazol-2-ylidene was synthesized by the direct metalation of N-(3-bromopropyl)-N’-thioether di-functionalized imidazolium bromide (2) with Pd(OAc)₂ in the presence of NaOAc and NaBr at room temperature using CH₂Cl₂ as solvent. The structure was characterized by NMR, HR-MS and X-ray crystallography. The results showed that complex 3 consists of two independent molecules with configuration of S_C, R_S in molecule a, and S_C, S_S in molecule b, respectively. The crystal is triclinic, P1 space group, with a = 8.4815(3), b = 8.6338(3), c = 19.2371(7) Å, V = 1245.66(8) ų, and Z = 2 (at 293(2)K).

Graphical Abstract

A chelating N-heterocyclic carbene palladium complex (3) consists of two independent molecules with configurations of S_C, R_S and S_C, S_S respectively has been synthesized through the direct metalation of the precursor imidazolium bromide (2).

A novel 2,4-dibromo-6-(1H-phenanthro[9,10-d]imidazol-2-yl)phenol crystal has been reported and characterized by FT-IR, ¹H NMR, ¹³C NMR. Single crystal XRD studies reveals that the compound crystalizes into triclinic crystal system with P-1 space group, and crystallographic data has been deposited in the Cambridge crystallographic data center with CCDC Number: 2246180. Various computational analysis like, Hydrogen bond analysis, Molecular electrostatic potential analysis, Natural population analysis, hirshfeld surface, and Frontier molecular orbital analysis were performed to elucidate the structure of the crystal. Marcus-Hus semiclassical model for charge transfer in organic materials is applied for the calculation of charge transfer rate. The calculation of reorganization energy and coupling constant reveals that the compound could be investigated as hole transport material.

Graphical Abstract

Synthesis, characterization, and computational analysis of Imidazole-based Organic crystals as charge transport material.

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.