C−H...π(Ar)...H−C host-guest interactions in a novel air-stable cyanoborate clathrate

The host compound forms a coordinato-clathrate in a coordination assisted host lattice. The host lattice is provided by hydrogen bonding between the nitrogen atom of the cyano group and two hydrogen atoms from the phosphonium methyl group. Guest molecules ofp-xylene occupy constricted channels in the lattice. The twop-xylene molecules participate in C–H...(Ar)...H–C interactions. Results from searches of the Cambridge Structural Database for other C–H...(Ar)...H–C and C–H...(Ar) interactions are presented.     

Unclassical Hydrogen Bonds of C–H⋯N and C–H⋯Cl in the Crystal Structures of 2-((<Emphasis Type="Italic">E</Emphasis>)-1,3-diarylallylidene)malononitriles

Abstract  

The 2-((E)-3-(2-nitrophenyl)-1-(4-methoxyphenyl)allylidene)malononitrile and 2-((E)-3-(2-chlorophenyl)-1-(4-bromophenyl)allylidene)malononitrile were synthesized and characterized by IR, ¹H NMR, and elemental analysis. The molecular structures were further confirmed by X-ray diffraction analysis. The former 1, C₁₉H₁₃N₃O₃, is triclinic, space group P−1, a = 7.3834(13), b = 10.901(3), c = 11.227(2) ?, α = 88.64(2), β = 71.596(14), γ = 78.186(18), Z = 2, V = 838.5(3) ?³. The unclassical hydrogen bond of C–H⋯N links the molecules forming polymers. The latter 2, C₃₆H₂₀Br₂Cl₂N₄, is orthorhombic, space group Pnma, a = 20.900 (4), b = 7.0710 (11), c = 10.9170 (18) ?, Z = 2, V = 1613.4(5) ?³. The same hydrogen bond of C–H⋯N and another type of C–H⋯Cl hydrogen bond link the adjacent molecules forming polymers along a axis.     

Crystal Structures of Two Palladacycles from the C–H Activation of 2-(Thiophen-2-yl)pyridine

Abstract  

A C,N-bound palladacycle dimer has been synthesised by reaction of 2-(thiophen-2-yl)pyridine, LH, with palladium acetate in acetic acid. Characterisation by single crystal X-ray diffraction showed the palladacycle dimer, [(L)Pd(OAc)]₂, to crystallise in the monoclinic space group P2₁/n with cell parameters a = 9.5853(1) ?, b = 19.1332(3) ?, c = 12.3889(2) ?, β = 103.732(1)°. Reaction of [(L)Pd(OAc)]₂ with triphenylphosphine afforded a trans-substituted monomeric complex, [(L)PdPPh₃(OAc)] which was also analysed using single crystal X-ray diffraction. [(L)PdPPh₃(OAc)] crystallises in the monoclinic space group P2₁/c with cell parameters a = 9.4839(1) ?, b = 11.0427(2) ?, c = 26.0770(4) ?, β = 95.022(1)°.     

One Porous Supramolecular Complex Assembled from Ionic and Neutral Hydrogen-bonds of N–H···O and C–H···O

Abstract  

The imidazolyl derived complex N,N′-butylenebis(imidazole):(oxalic acid)_0.5 was prepared and structurally characterized by X-ray crystallography. The title compound crystallizes in the triclinic, space group P-1, with a = 4.4373(9) ?, b = 12.882(3) ?, c = 15.319(3) ?, α = 99.91(3)°, β = 94.53(3)°, γ = 98.72(3)°, V = 847.7(3) ?³, Z = 2. Two N,N′-butylenebis(imidazole) and two oxalic acid molecules form an annulus via intermolecular hydrogen bonds, with internal dimensions of about 7.1 × 11.1 ?. Neighboring annuluses were connected by N–H···O and C–H···O interactions to form 1D double chain structure. Adjacent double chains stacked just above each other along the a-axis direction, this arrangement of the double chains leads the extended supramolecular architecture to show a three-dimensional porous network.     

1-[(Pyridine-2-ylamino)methyl]pyrrolidine-2,5-dione: Supramolecular Aggregation via Cooperative H-bonded Network of N–H···N and C–H···O Interactions

Abstract  

In the crystal structure of the title compound, C₁₀H₁₁N₃O₂, the pyrrolidine ring adopts a puckered envelope conformation. The supramolecular architecture is dictated by the cooperative H-bonded network of centrosymmetric dimers of N–H···N and C–H···O interactions. Two edge to face C–H···π interactions involving the centroid of the pyrrolidine ring contribute to the supramolecular aggregation.     

Analysis of C–H···O Intermolecular Interactions in 4-Androstene-3,17-dione

Abstract  4-Androstene-3,17-dione was synthesized for its crystallographic analysis and to investigate the role of intra- and intermolecular interactions in steroids. It crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters, a = 7.330(2) ?, b = 13.095(11) ?, c = 16.856(17) ?, V = 1,618(5) ?³ and Z = 4. The structure has been solved by direct methods using X-ray diffraction techniques and the refined final reliability index for the computed structure is 0.033 for 1,655 observed reflections. Two six-membered rings B and C exist in chair conformation while ring A occupies a sofa conformation. The five-membered ring D depicts envelope conformation. The C–H···O intermolecular hydrogen interaction results into a ring like configuration which makes the dimers. Index Abstract   Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors [1]. Androgens have been used in breast cancer when excision or radiotherapy have failed to control the progress of local recurrent disease. They are also used in case where the primary tumour is inoperable or is unsuited for, or resistant to, radiotherapy. Androgens are also believed to be responsible for linear bone growth in both males and females, probably in conjunction with somatotrophin [2]. In continuation to our work on the single crystal growth of X-ray diffraction quality crystals and crystallographic analysis of steroidal molecules, [3-7] synthesis and crystallographic study 4-androstene-3,17-dione is reported in this paper.     

Unusual nucleotide stability through C–H ⋅ ⋅ ⋅ water interaction in crystal: Recognition of nucleotide-water duplex-helix

The direct and indirect roles of the C2- and C8-bonded water molecules (C–H    O_W) in the stabilization of unusual inosine monophosphate containing nucleotides have been observed in their highly hydrated and amino acid cocrystals, which have been discussed in this work for the first time. The intermolecular H-bonding of W_R (the oxygen of ribose 2- and 3-hydroxyls bonded water molecule, O2    W_R    O3) with the C2–H bonded O_W's (O_W    W_R 2.43–2.78 Å) can influence the ribose and thus the nucleotide stability, whereas the water molecule (O_W) of C8–H    O_W can participate in the base stability by sandwiching the stacked purines through N7    O_W    N7 intermolecular interactions, with N7    O_W 2.63–2.75 Å. However, in some cases the water oxygen (O_W) of C8–H can get intermolecularly H-bonded to water molecular oxygen W_N (with O_W    W_N 2.57–2.85 Å), which has previously stabilized the nucleotide single-strand through intermolecular stacking N7    W_N    N7 interaction (N7    W_N 2.56–2.63 Å). The conjugal survival of the H-bonded nucleotide single-strand with the water-helix thus forming the duplex and its stabilization through the C–H    O_W mediated water molecular (O_W) cooperative H-bonding network, specially with the ribose and the base units, in the crystals could favor the support of single-stranding potentiality and thus the stability of the purine-rich RNAs or the small unusual nucleotides in the aquated environment besides the other interactive factors.     

C–H···π and C=O···π Intermolecular Interactions in Dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate

Abstract A new pyrazine compound, has been synthesised and characterised by single-crystal X-ray diffraction: monoclinic, P2₁/c with a = 11.0707(3) ?, b = 5.23700(10) ?, c = 16.6997(5) ?, β = 103.5385(16)°, Mr = 376.40, V = 941.30(4) ?³, Z = 2. Each molecule possesses C _i symmetry with the two halves of the molecule related by an inversion centre. C–H···π and C=O···π interactions held the molecules together. Index Abstract C–H···π and C=O···π intermolecular interactions in dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate Joana A. Silva, Ana C. Santos, Ana T. Marques, Manuela Ramos Silva, Ana Matos Beja, Abílio J. F. N. Sobrala In dibenzyl-3,6-dimethylpyrazine-2,5-dicarboxylate, each molecule possesses C _i symmetry. The molecules are assembled in chains via carbonyl···π interactions. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Microstructure and properties of spark plasma sintered Fe–Cr–Mo–Y–B–C bulk metallic glass

Fabrication of Fe-based amorphous alloy using spark plasma sintering (SPS) process has been reported. Fully amorphous compacts with ～95% relative density were successfully sintered at temperature about 100 °C lower than glass transition temperature (T_g: 575 °C). Formation of crystalline Fe₂₃(C, B)₆ phases within near-fully dense (～99%) amorphous matrix is observed at sintering temperatures (>550 °C) close to glass transition temperature. Microstructure evolution in sintered compacts indicated that density, degree of crystallinity, and mechanical properties can be effectively controlled by optimizing SPS parameters.     

Effect of Mo element on the properties of Fe–Mo–P–C–B bulk metallic glasses

Bulk Fe_80?xMo_xP₁₀C_7.5B_2.5 (x = 5–10 at.%) metallic glasses are synthesized by copper mold casting, which have a critical diameter up to 3 mm, fracture strength over 3000 MPa, plastic strain up to 2.5% and saturation magnetization reaching 1.1 T. Results show that the glass forming ability and strength increase with increasing Mo content, while the plasticity and saturation magnetization do otherwise. These Mo content dependent properties are illuminated with the atomic interactions in the alloys that could be strengthened by suitable addition of Mo element. The effects of Mo on the properties of the alloys imply that proper Mo element should be chosen in designing Fe-based glassy alloys with desired properties.     

Free volume and viscosity of Fe–Co–Cr–Mo–C–B–Y bulk metallic glasses and their correlation with glass-forming ability

In this work, the variation of the glass-forming ability (GFA) in Fe–Co–Cr–Mo–C–B–Y alloy system with Co addition has been investigated from the viewpoints of non-isothermal viscosity and free volume. The best GFA for the alloy containing 7% Co is found to closely relate with its highest viscosity, and the minimum sizes and lowest concentrations of the intermediate and largest open volumes. The results may provide more insights into the formation mechanism of metallic glasses.     

The structure and conformation of the tryptophanyl diketopiperazines cyclo(Trp–Trp)·C2H6SO and cyclo(Trp–Pro)

The structure and conformation of the cyclic dipeptides [cyclo(L-Trp–L-Trp)·C₂H₆SO] and cyclo(L-Trp–L-Pro) have been investigated with X-ray crystallographic and spectroscopic methods. Cyclo(L-tryptophanyl-L-tryptophanyl)·DMSO solvate crystallized in the space group P2 ₁2₁2₁ with cell dimensions a = 6.193(2), b = 11.545(3), c = 31.117(4) Å. The crystal structure is stabilized by four hydrogen bonds (three intermolecular hydrogen bonds and one intramolecular bond). The first intermolecular bond is between the oxygen of DMSO and the nitrogen of indole ring 2, in contrast to the second intramolecular hydrogen bond between the nitrogen of indole ring 1 and the oxygen of DMSO. The two remaining intermolecular hydrogen bonds are between the nitrogens of the DKP ring and the carbonyl oxygens of the DKP ring. The values of ^1A ₁ (–45.764) and ^1A ₂ (67.437) indicate an extended side chain conformation for Trp residue 1 (E_N) and a folded conformation for Trp residue 2. The DKP ring is more planar than in other cyclic dipeptide compounds (₁ = 11.414, ₁ = –7.516, ₂ = 12.471, and ₂ = –8.256). In cyclo(L-Trp–L-Trp) the C resonance of L-tryptophan (29.88 ppm) is shifted upfield 0.82 ppm when compared with the same resonance in cyclo(L-Trp–L-Gly) (30.7 ppm) and cyclo(L-Leu–L-Trp) (30.7 ppm). Two conformations of cyclo(Trp–Pro) crystallized in the space group P1 with cell dimensions a = 5.422(1), b = 9.902(1), c = 13.443(2) Å, = 80.42(1), = 78.61(1), and = 89.13(1)°. The conformation of the backbone and the orientation of the aromatic side chains for these conformers are very similar. The DKP rings for both conformers adopt a typical boat conformation in contrast to the flattened chair conformation observed for cyclo(Tyr–Pro) and cyclo(Phe–F-Pro). The tryptophan side chains of these conformers are folded towards the diketopiperazine (DKP) ring. The pyrrolidine ring for conformer 1 can be described as an envelope (Cs–C-endo) conformation in contrast to the pyrrolidine ring symmetry for conformer 2 which is an intermediate between C_s and C₂ rather than pure C_s for the proline ring with C-endo and C-exo with respect to C. The two prolyl rings are puckered at the -carbon atoms which deviate from the best planes defined by the four remaining atoms. The crystal structures are stabilized by four intermolecular hydrogens bonds. An intermolecular bond between the nitrogen of the indole ring (conformer 1) and the carbonyl oxygen of the DKP ring (conformer 2) was observed. The second hydrogen bond is between the nitrogen of the indole ring (conformer 2) and the carbonyl oxygen of the DKP ring (conformer 1). The last two hydrogens involve the carbonyl oxygens of the DKP rings and the nitrogens of the DKP rings [carbonyl oxygen of DKP ring (conformer 1)––––nitrogen of DKP ring (conformer 2); nitrogen of DKP ring (conformer 1)––––––carbonyl oxygen of DKP ring (conformer 2)].     

Regiospecificity of nucleotide–amino acid mating vs. water dynamics: a key to protein–nucleic acid assemblies: structure of unidecahydrated inosine-5′-monophosphate and L–glutamic acid (2C10H13N4O8P·C5H11NO4·11H2O) cocrystal at atomic resolution

The crystal structure of a unidecahydrated cocomplex between two Inosine-5-monophosphates (IMP) and one L-glutamic acid has been determined by X-ray crystallographic methods. The crystal belongs to the monoclinic space group P2₁ with cell dimensions a = 8.650(1), b = 21.900(1), c = 12.370(1) Å, and = 110.4°(9). This structure reveals extensive hydrogen bonding of glutamic acid to the nucleotide through direct and water-mediated interactions. The phosphate oxygens (O3B and O1B) seem to prefer nonspecific interaction with the functional sites of glutamic acid (OE2 ······O1B = 1.78 Å, NA······O3B = 2.73 Å, OH······O3B = 3.06 Å), whereas the bases prefer specific (O······N3B = 2.88 Å) binding. A solvent mediated N7A···W5···N7B hydrogen bond used for stabilization of the stacked purine bases has been observed as in other amino acid–nucleotide cocrystals. Glutamic acid occupies the same hydrophilic region in the nucleotide cocrystal as was found in glutamine–inosine monophosphate (Gln–IMP) and in serine–inosine monophosphate (Ser–IMP) complexes through substantial replacement of free and bound water molecules. This points to the dynamic hydrogen bonding nature of the water molecules and their stereochemical cooperation for the placement of amino acid through the polycoordination within the crystal.     

Effect of Mo–Fe substitution on glass forming ability and thermal stability of Fe–C–B–Mo–Cr–W bulk amorphous alloys

Amorphous Fe_67?xC₁₀B₉Mo_7+xCr₄W₃ (x = 1–7 at.%) plates with 0.64 mm thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry, differential thermal analysis, and X-ray diffraction. The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe₆₂C₁₀B₉Mo₁₂Cr₄W₃ was the best glass former in this study, demonstrating a supercooled liquid region, ΔT_x = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three phased evolution during crystallization. A second set of heat treatments was performed to identify each phase. An analysis of phase evolution revealed a distinct dependence of phase evolution with stepwise substitution of Mo for Fe in this system.     

Structure of progesterone hydroquinone monohydrate (1∶1∶1), C21H30O2·C6H6O2·H2O

The crystal structure of progesterone hydroquinone monohydrate was determined by means of X-ray diffraction methods:M _r=442.6, orthorhombic,P2₁2₁2₁,a=14.680(2),b=22.725(3),c=7.334(1) Å,V _a=2446.6(6) ų,Z=4,D _x=1.190 M gm^–3, MoK radiation ,(MoK)=0.75 cm^–1,F(000)=948. The structure was solved usingMultan;R=0.059,R _w=0.059 for 2736 reflections. This progesterone molecule has the most flattenedA ring, relative to the rest of the skeleton, of all progesterone molecules studied so far. Steroid, hydroquinone, and water molecules form, by means of hydrogen bonds, two parallel chains connected with each other by hydrogen bonds.The authors thank Dr. A. Szyczewski for supplying crystals. This research was supported by the project RP.II.10 from the Polish Ministry of National Education and by PHS Grant No. DK26546.     

C12H9SN晶体铁弹相变的研究

采用慢度曲面法研究C12H9SN晶体的铁弹相变.在现有实验数据的基础上,模拟计算C 12 H9 SN晶体高温正交相的弹性劲度系数对慢度曲面的影响.结果表明,非对角元c12,c13,c23的变化对慢度曲面最大值的取向没有影响,同时也确定出与该相变直接相关的弹性劲度系数为c55.该晶体相变的对称性变化是由高温正交相mmm点群变成低温单斜相2/m点群.     

The crystal and molecular structure of 14-β-N-pentylaminomorphinone,C22H28N2O3

The crystal and molecular structure of 14--N-pentylaminomorphinone (14--N-PAM), C₂₂H₂₈N₂O₃, has been determined by analysis of single crystal X-ray diffraction data. The compound crystallized at room temperature in the orthorhombic system, space group P2₁2₁2₁ witha=12.4535(8),b=13.7855(8),c=11.710(1) Å,V _c =2010.3(2) ų,Z=4,D _x =1.22 gm/cm³,(Cu K)=6.58 cm^–1, andF(000)=792. The final refinement yieldedR=0.051,R _w =0.059 for 328 variables with 1133 unique observed reflections. The absolute configuration is established via the synthesis from thebaine by the noninvolvement of certain asymmetric centers. The molecule is found to have as its central structure a T shape similar to that found in morphine and codeine. The distinctive feature of the molecule is the 14--N-pentylamino lipophilic side chain. Molecular modeling studies on the alkylamino chain result in the identification of clusters of conformations based on energy and dihedral angle criteria. Selected conformations are compared to 19-propylthevinol (etorphine), another potent analgesic which contains a lipophilic hydroxyalkyl substituent at C19. The enhanced analgesic activity of 14--N-pentylaminomorphinone is postulated to arise from an overall morphine-like contact with the receptor augmented by the interaction of the aliphatic chain with a lipophilic receptor pocket.