3-[4-Bromo-α(<Emphasis Type="Italic">R</Emphasis>*)-methoxybenzyl]-6-chloro-3(<Emphasis Type="Italic">S</Emphasis>*),4(<Emphasis Type="Italic">S</Emphasis>*)-dihydroxychroman: X-ray and DFT Studies

Sodium borohydride reduction of E-3-benzylidenechromanone epoxides in dry methanol has afforded 3(S*), 4(S*)-dihydroxy-3-[α(R*)-methoxybenzyl]chromans as an interesting class of products, the structures of which have been assigned mainly from spectral data and consideration of the mechanistic aspects. X-ray diffraction study of one of them, 3-[4-bromo-α(R*)-methoxybenzyl]-6-chloro-3(S*),4(S*)- dihydroxychroman, is performed. The title compound crystallizes in the monoclinic sp. gr. P2₁/n, with a = 13.336(6) Å, b = 10.866(5) Å, c = 27.166(11) Å, β = 95.193(6)°, V = 3920(3) ų, and Z = 8. Supramolecular construction of the compound involves O–H···O intermolecular hydrogen bonds as well as three other types of non-covalent interactions which are responsible for crystal packing. Density functional theory was applied for geometry optimization, molecular orbital calculations, and prediction of UV spectral features. The geometric parameters (bond lengths, bond angles, and dihedral angles) for the representative compound obtained from density functional theory with B3LY6-31G basis set were in good agreement with experimental values.     

Crystal and Molecular Structure of <Emphasis Type="Italic">N</Emphasis>-(Phenylthio)phthalimide

The title compound N-(Phenylthio)phthalimide has been synthesized and characterized by FT-IR, NMR, and X-ray single-crystal determination. The compound crystallizes in the triclinic sp. gr. \(P\bar 1\) with Z = 2. The title compound is not planar. The dihedral angle between the phthalimide and phenyl ring systems is 77.41(8)°. The crystal structure is stabilized by intermolecular π...π and C–H...π interactions.     

Crystal structure of 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl]benzamide : <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide (1 : 1)

The title compound, 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl] benzamide:N,N-dimethylformamide (1: 1), (C₁₅H₁₁N₃O₂S₂ · C₃H₇NO), was synthesized, and its structure was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the monoclinic space group P2₁/n with a = 10.8714(7), b = 9.0497(5), c = 19.8347(13) Å, β = 91.093(5)°, Z = 4. The crystal structure is stabilized by N–H···S, C–H···O and N–H···O hydrogen bonds. The π···π interactions are also observed between the rings.     

Crystal Structure of Ethyl 6-Amino-5-cyano-4-(4-fluorophenyl)- 2,4-dihydropyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazole-3-carboxylate

Ethyl 6-amino-5-cyano-4-(4-fluorophenyl)-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylate was synthesized based on a commercially available trisodium citrate dihydrate as an inexpensive and eco-friendly catalyst for the first-time via one-pot tandem Knoevenagel-cyclocondensation of malononitrile, 4-f luorobenzaldehyde and in situ generated ethyl 5-oxo-2,5-dihydro-1H-pyrazole-3-carboxylate in aqueous ethanol at room temperature and its crystal structure is determined by X-ray structure analysis. The crystals are triclinic, sp. gr. \(P\bar 1\), a = 8.7914(7) Å, b = 11.3632(8) Å, c = 11.4005(9) Å, α = 62.278(7)°, β = 71.099(7)°, γ = 80.856(6)°, Z = 2, R = 0.0544 for 2491 observed ref lections. Pyran and pyrazole rings are almost coplanar and phenyl ring is almost perpendicular to these two rings. Pyran ring adopts boat conformation. The crystal structure is stabilized by N–H···N, N–H···O, C–H···F, and C–H···π hydrogen interactions. In addition, a number of weak π···π interactions also contribute to stabilize the crystal structure.     

Molecular and Crystal Structure of 2-{(<Emphasis Type="Italic">E</Emphasis>)-[(5-Chloro-2-methoxyphenyl)imino]methyl}-4-nitrophenol

The molecular structure of the title compound, C₁₄H₁₁ClN₂O₄, was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic sp. gr. P2₁/c with Z = 4. The title compound, C₁₄H₁₁ClN₂O₄, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state.The molecule is almost planar and the dihedral angle between the planes of two aromatic ring is 2.2(1)°. The molecular structure is stabilized by intramolecular O–H···N hydrogen bond which generates a six-membered ring. In the crystal structure, the molecules are linked together by intermolecular C–H···O interactions.     

Crystal structure of (<Emphasis Type="Italic">E</Emphasis>)-3-fluoro-N-((5-nitrothiophen-2-yl)methylene)aniline

The structure of the title compound C₁₁H₇FN₂O₂S was characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/n with Z = 12, i.e. with three molecules in asymmetric unit. The molecules are not planar: the dihedral angles between the planes of thiophene and the benzene rings are 42.3(3)°, 42.0(3)°, and 48.9(2)°. In the crystal, intermolecular C–H···F interactions link the molecules through R₂² (14) ring motif. The crystal packing is also stabilized by π···π interactions.     

Synthesis,antityrosinase activity of curcumin analogues,and crystal structure of (1<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">E</Emphasis>)-1,5-bis(4-ethoxyphenyl)penta-1,4-dien-3-one

Five derivatives of curcumin analogue (R = OCH₂CH₃ (1), R = N(CH₃)₂ (2), R = 2,4,5-OCH₃ (3), R = 2,4,6-OCH₃ (4), and R = 3,4,5-OCH₃ (5)) were synthesized and characterized by ¹H NMR, FT-IR and UV–Vis spectroscopy. The synthesized derivatives were screened for antityrosinase activity, and found that 4 and 5 possess such activity. The crystal structure of 1 was determined by single crystal X-ray diffraction: monoclinic, sp. gr. P2₁/c, a = 17.5728(15) Å, b = 5.9121(5) Å, c = 19.8269(13) Å, β = 121.155(5)°, Z = 4. The molecule 1 is twisted with the dihedral angle between two phenyl rings being 15.68(10)°. In the crystal packing, the molecules 1 are linked into chains by C?H···π interactions and further stacked by π···π interactions with the centroid–centroid distance of 3.9311(13) Å.     

Synthesis and Crystal Structures of Ethyl 2-(4-Methoxyphenyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazole-5-carboxylate Dihydrate and Its Building Block 4-Fluoro-3-nitrobenzoic Acid

The title compound, ethyl 2-(4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate dihydrate (5), was synthesized and its crystal structure was studied by single-crystal X-ray diffraction technique. Compound 5 is crystallized in the centrosymmetric triclinic space group \(P\bar {1}\) with Z?=?4 and Z′?=?2, and unit-cell parameters of a?=?8.9190 (3) Å, b?=?12.6888 (4) Å, c?=?14.7111 (5) Å, α?=?98.4855 (10)°, β?=?101.6379 (9)°, γ?=?95.4346 (10)° and V?=?1599.43 (9) ų. Its starting material, 4-fluoro-3-nitrobenzoic acid (1), is crystallized in the non-centrosymmetric monoclinic space group P2₁ and Z?=?4 with unit-cell parameters of a?=?3.7170 (4) Å, b?=?12.6475 (13) Å, c?=?15.5237 (15) Å, α?=?90°, β?=?91.9786 (16)°, γ?=?90° and V?=?729.35 (13) ų. It was noted that strong hydrogen bonds play important roles in the crystal packing of both compounds, especially in 5, in which the co-crystallized water molecules act as both strong hydrogen bond donor and strong hydrogen bond acceptor.

Graphical Abstract

Two molecule of compound 5 crystallized in a non symmetrical manner with four co-crystallized water molecules which play an important role in the crystal packing as strong hydrogen-bond donors.

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Crystal Structure of Two <Emphasis Type="Italic">V</Emphasis>-shaped Ligands with <Emphasis Type="Italic">N</Emphasis>-Heterocycles

Two V-shaped ligands with N-heterocycles, bis(4-(1H-imidazol-1-yl) phenyl)methanone (1), and bis(4-(1H-benzo[d]imidazol-1-yl)phenyl)methanone (2) have been synthesized and characterized by elemental analyses, IR and 1H NMR spectroscopy. Crystal structures of 1 and 2 have been determined by X-ray diffraction. The crystal of 1 is monoclinic, sp. gr. P2₁/c, Z = 4. The crystal of 2 is orthorhombic, sp. gr. Fdd2, Z = 8. X-ray diffraction analyses show that the V-shaped angles of 1 and 2 are 122.72(15)° and 120.7(4)°, respectively. Intermolecular C–H···O, C–H···N, C–H···π, and π···π interactions link the components into three-dimensional networks in the crystal structures.     

Crystal Structure of 2-((<Emphasis Type="Italic">E</Emphasis>)-(5-Bromo-2- hydroxybenzylidene)hydrazono)-1,2-diphenylethanone

The molecular structure of the title compound, C₂₁H₁₅Br₁N₂O₂, was characterized by single crystal X-ray diffraction. The compound crystallizes in the triclinic sp. gr. \(P\bar 1\) with Z = 2. The molecule is not planar: the dihedral angle between the planes of two aromatic rings [C1/C6] and [C16/C21] is 84.9(2)°. The other dihedral angle between two aromatic rings [C9/C14] and [C16/C21] is 88.8(2)°. The title compound exists as a phenol-imine tautomer, in which a strong intramolecular O–H···N hydrogen bond is formed. This study verifies the preference of the phenol-imine tautomeric form in the solid state. A π–π stacking interactions are also observed, which may influence crystal stability: the distance between centroids is 3.702(2) Å.     

Synthesis and Crystal Structure of 7,8,9,10-Tetrahydro-2-bromo-cyclohepta[<Emphasis Type="Italic">b</Emphasis>]indol-6(5<Emphasis Type="Italic">H</Emphasis>)-one

The title compound, C₁₃H₁₂BrNO, was synthesized and characterised by IR, ¹H and ¹³C NMR spectroscopy. The proposed structure was confirmed by single crystal X-ray diffraction. The single crystal data revealed that the compound crystallizes in the triclinic system, sp. gr. P1, with Z = 2. The sevenmembered ring exhibits a slightly distorted envelope conformation. N–H···O hydrogen bonds form a centrosymmetric dimer, these interactions create a stair-like chain of molecules that interacts only loosely with neighbouring chains via van der Waals interactions, and C–H···π contacts are found in the crystal structure.     

Thermal Expansion of EuF<Subscript>2 + <Emphasis Type="Italic">x</Emphasis></Subscript> Single Crystals and Their Thermal Stability

Thermal expansion of an EuF_2.136 nonstoichiometric crystal with the fluorite structure type (Eu _0.864 ²⁺ Eu _0.136 ³⁺ F_2.136, lattice parameter 5.82171(5) Å) has been experimentally investigated in the temperature range of 9–500 K. The coefficient of thermal expansion is α = 15.8 × 10^–6 K^–1 at T = 300 K. The observed anomalies in the behavior of the coefficient of thermal expansion at T > 400 K are related to the oxidation processes with partition of Eu²⁺ ions. It is established by differential scanning calorimetry that the onset temperature of EuF_{2 + x} oxidation in air is 430 K and that this process occurs in three stages. X-ray diffraction analysis shows that the oxidation is accompanied by the formation of a phase mixture based on two modifications of the Eu _{1– y} ³⁺ Eu _y ²⁺ F_3–y solid solution with the structure types of tysonite (LaF₃), orthorhombic β-YF₃ phase, and europium oxyfluorides of variable composition EuO_1–xF_{1 + 2x}, with dominance of the latter.     

Synthesis,Characterization, and Crystal Structure of (2<Emphasis Type="Italic">E</Emphasis>)-3-(4-Fluorophenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one

The title chalcone, of formula C₁₅H₁₁F₁O_2, crystallized in the orthorhombic space group P2₁2₁2₁ (# 19) with crystal parameters a?=?6.9998(8) Å, b?=?12.6740(15) Å, c?=?12.8997(15) Å, V?=?1144.4(2) ų, Z?=?4, determined at 100 K with MoKα radiation. The solid-state structure displays an intramolecular S(6) hydrogen bond and the crystal architecture is maintained by intermolecular F?H, O?H, and C?C short contacts. A DFT geometry optimization is compared with the experimental structure. As ¹⁹F NMR spectroscopy can be used for metabolic tagging of biologically active compounds (including chalcones), the solution-state ¹⁹F chemical shift and ¹³C¹⁹F coupling constants (ⁿJ) are also reported.

Graphical Abstract

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Synthesis of Nonstoichiometric Samarium Fluoride SmF<Subscript>2 + <Emphasis Type="Italic">x</Emphasis></Subscript>

The products of interaction of SmF₃ with metallic Sm⁰, Si, and molecular hydrogen in quartz, graphite, and molybdenum containers have been investigated by X-ray diffraction. It is shown that reduction occurs with the formation of nonstoichiometric cubic SmF_{2 + x} (sp. gr. Fm3?m, unit-cell parameter a = 5.8517(2) Å) with a content x = 0.108 only in the case of synthesis of SmF₃ with metallic Sm⁰ in a quartz ampoule. The transformation of the SmF_{2 + x} phase composition in air at room temperature has been studied for the first time. It is found that SmF_2.108 passes into the superstructural phase Sm₁₃F_32–δ (sp. gr. R3?) with the unit-cell parameters a = 14.7354(4) Å and c = 10.1156(4) Å for 60 days. The use of Sm⁰, Si, and H₂ as reducing agents for SmF₃ is inefficient because of the weak tendency of the latter to reduction: the process occurs also with a low yield of the Sm₁₃F_32–δ phase and of the α-SmF₃-based phase as impurity in the case of direct reduction by hydrogen.     

Synthesis,Spectroscopic and Crystal Structure Analysis of <Emphasis Type="Italic">N</Emphasis>-[imidazolidin-2-ylidene]-5-(thien-2-yl)[1,3,4]thiadiazole-2-amine

The crystal structure of the title compound has been determined. The compound crystallizes in the monoclinic space group P2₁/c with a = 5.9885(2) Å, b = 14.7345(4) Å, c = 12.3719(4) Å, β = 96.655(5)°, V = 1084.31(8) Å³, z = 4. An intramolecular N–H···N hydrogen bond forms a pseudo-six-membered ring with graph set S ¹ ₁(6). The crystal structure is stabilized by intermolecular interactions of the type N–H···N and C–H···N. The packing motifs in accordance with Etter’s analysis are R ² ₂(8) corresponding to N–H···N dimer and that generated by the chain is C(7).     

Molecular Dynamics Simulation of the Structure and Ion Transport in the Ce<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Gd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2 – δ</Subscript>|YSZ Heterosystem

Molecular dynamics simulation has been used to develop a realistic atomistic model of two-layer Ce_{1 – x}Gd _x O_{2 – δ}|YSZ heterosystem. It is shown that Ce_{1 – x}Gd _x O_{2 – δ} and YSZ layers (about 15 and 16 Å thick, respectively) retain their crystal structure on the whole. The main structural distortions are found to occur near the Ce_{1 – x}Gd _x O_{2 – δ}|YSZ geometric interface, within a narrow interfacial region of few angstroms thick. Both the generalized diffusion characteristics of the system as a whole and the oxygen diffusion coefficients in the layers are calculated, and the diffusion activation energies are determined.     

Synthesis,structural characterization,and DFT calculations of 3-buthyl-4-(3-methyl-3-mesitylcyclobut-1-yl)-1,3-thiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

The title compound, C₂₁H₂₉NS₂, has been synthesized and its crystal structure has been determined from single crystal X-ray diffraction data. Crystals are monoclinic, a = 11.4923(8), b = 13.1842(7), c = 14.6583(8) Å, β = 109.983(6)°, sp. gr. P2₁/c, Z = 4. Mesityl and thiazole groups are in cis positions with respect to the cyclobutane ring. The cyclobutane ring is puckered, with a dihedral angle of 26.6(2)° between the two three-atom planes. The crystal structure involves one weak intermolecular C–H···S hydrogen-bond. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d, p) basis set in ground state. Geometric parameters (bond lengths, bond angles and torsion angles) and vibrational assignments have been calculated theoretically and compared with the experimental data.     

Crystal structure of <Emphasis Type="Italic">L</Emphasis>-alanine phosphate

The crystal structure of L-alanine phosphate (C₃O₂NH₇ · H₃PO₄) is determined by the single-crystal diffraction technique; a = 11.918(1) Å, b = 9.117(1) Å, c = 7.285(1) Å, γ = 104.7(1)°, space group P2₁, and Z = 4. The amino group of the alanine is protonated by the hydrogen atom of the phosphoric acid. Pairs of H₂PO ₄ ^? hydrogen-bonded ions are packed into layers alternating with layers of alanine molecules in the crystal. No hydrogen bonds are formed immediately between the alanine molecules.     

X-ray crystallography of methyl (6-amino-5-cyano-2-methyl-4-(2-nitrophenyl)-4<Emphasis Type="Italic">H</Emphasis>-pyran)-3-carboxylate

The organic carbonitrile namely methyl (6-amino-5-cyano-2-methyl-4-(2-nitrophenyl)-4H-pyran)- 3-carboxylate is synthesized via one-pot multi-component reaction at room temperature using commercially available urea as inexpensive and environmentally benign organo-catalyst and its crystal structure is determined by X-ray technique. The crystals are monoclinic, sp. gr. C2/c, a = 12.3069(8) Å, b = 9.7023(7) Å, c = 24.812(2) Å, β = 94.862(6)°, Z = 8. The dihedral angle between pyran and phenyl rings is 87.8(1)°; the pyran ring is almost planar The dihedral angle between the mean planes of phenyl ring and nitro group is 44.4(2)°. The crystal structure is stabilized by N?H···N and N?H···O hydrogen bonds. In addition, C?H···π interactions are also observed in the crystal structure.     

Crystallization and Preliminary X-ray Diffraction Study of Purine Nucleoside Phosphorylase from the Thermophilic Bacterium <Emphasis Type="Italic">Thermus thermophilus</Emphasis> Strain HB27

Recombinant purine nucleoside phosphorylase from the thermophilic Thermus thermophilus strain encoded by the TT_C0194 gene was purified to homogeneity. The crystallization conditions for the enzyme were found by the vapor-diffusion technique. The crystals of the enzyme suitable for X-ray diffraction were grown under microgravity conditions by the capillary counter-diffusion method. The crystals belong to sp. gr. P2₁2₁2₁ and have the following unit-cell parameters: a = 89.9 Å, b = 121.0 Å, c = 215.7 Å, α = β = γ = 90°. The X-ray diffraction data set suitable for the determination of the three-dimensional structure of purine nucleoside phosphorylase was collected from the grown crystals at the SPring-8 synchrotron facility to 2.5 Å resolution.