Structures for monodisperse oligoamides. A novel structure for unfolded three-amide nylon 6 and relationship with a three-amide nylon 6 6

Three-amide oligomers of nylon 6 and nylon 6 6 have been investigated using electron microscopy (imaging and diffraction), X-ray diffraction, and computational modeling. A new crystal structure has been discovered for the three-amide oligomer of nylon 6. This material crystallizes from chloroform/dodecane solutions into an unfolded crystal form that has progressively sheared hydrogen bonding in two directions between polar (unidirectional) chains. This structure is quite different from the usual room temperature α-phase structure of chain-folded nylon 6 crystals, in which alternatingly sheared hydrogen bonding occurs between chains of opposite polarity in only one direction. The occurrence of this new structure illustrates the extent to which progressively sheared hydrogen bonding is preferred over alternatingly sheared hydrogen bonding. Indeed, the progressive hydrogen bonding scheme occurs in the three-amide nylon 6 material even though it requires a disruption to the lowest potential energy all-trans conformation of the chain backbone, and requires all the chains in each hydrogen-bonded layer to be aligned in the same direction. We believe the presence of chain folding, which necessarily incorporates adjacent chains of opposite polarity into the crystal structure, prevents the formation of this new crystal structure in the nylon 6 polymer. In contrast, the three-amide nylon 6 6 crystal structure is analogous to the polymeric nylon 6 6 α-phase structure, found in both fibers and chain-folded crystals, and consists of progressive hydrogen-bonded sheets which stack with a progressive shear. In both structures, the molecules (≈ 3 nm in length) form smectic C-like layers with well-orchestrated stacking of 2.2 nm to form a three-dimensional crystal. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2849–2863, 1998     

Chirality organization of ferrocenes bearing podand dipeptide chains: synthesis and structural characterization

A variety of ferrocenes bearing podand dipeptide chains have been synthesized to form an ordered structure in both solid and solution states and have been investigated by 1H NMR, FT-IR, CD, and X-ray crystallographic analyses. Conformational enantiomerization through chirality organization was achieved by the intramolecular hydrogen bondings between the podand dipeptide chains. The single-crystal X-ray structure determination of the ferrocene 2 bearing the podand dipeptide chains (-D-Ala-D-Pro-OEt) revealed two C2-symmetric intramolecular hydrogen bondings between CO (Ala) and NH (another Ala) of each podand dipeptide chain to induce the chirality-organized structure. The molecular structures of the ferrocene 1 composed of the podand L-dipeptide chains (-L-Ala-L-Pro-OEt) and 2 are in a good mirror image relationship, indicating that they are conformational enantiomers. An opposite helically ordered molecular arrangement was formed in the crystal packing of 2 as compared with 1. The ferrocene 2 exhibited induced circular dichroism (CD), which appeared at the absorbance of the ferrocene moiety. The mirror image of the CD signals between 1 and 2 was observed, suggesting that the chirality-organized structure via intramolecular hydrogen bondings is present even in solution. The ferrocene 4 bearing the podand dipeptide chains (-Gly-L-Leu-OEt) also showed an ordered structure in the crystal based on two intramolecular hydrogen bondings between CO (Gly) and NH (another Gly) of each podand dipeptide chain, together with intermolecular hydrogen bondings between CO adjacent to the ferrocene unit and NH (neighboring Leu) to create the highly organized self-assembly. A different self-assembly was observed in the crystal of the ferrocene 5 composed of the podand dipeptide chains (-Gly-L-Phe-OEt), wherein each molecule is bonded to two neighboring molecules through two pairs of symmetrical intermolecular hydrogen bonds to form a 14-membered intermolecularly hydrogen-bonded ring. These ordered structures based on the intramolecular hydrogen bondings in the solution state are also confirmed by 1H NMR and FT-IR.     

Unusual supramolecular assembly and nonlinear optical properties of l-histidinium hydrogen malate

A new nonlinear optical material, l-histidinium hydrogen malate, has been synthesized. The crystal structure was determined at 90 K by single-crystal X-ray diffraction in order to analyze its supramolecular structure. A new building block type has been found. The malate anions form head-to-side infinite chains parallel to [100], via O-H?O interactions, instead of the usual head-to-tail infinite chains found in other hydrogen malate salts. The l-histidine cations form chains parallel to [100] via N-H?O hydrogen bonds, with cations of adjacent chains in anti-parallel way. The compound shows a good optical second-harmonic generation capability with an effective second-order susceptibility estimated to be 0.70 of that for potassium dihydrogen phosphate.     

Beta-alanine-oxalic acid (1:1) hemihydrate crystal: structure, 13C NMR and vibrational properties,protonation character

The crystal structure of beta-alanine-oxalic acid (1:1) hemihydrate complex has been reinvestigated by X-ray diffraction method at 293 K. Formation of monoclinic crystal system belonging to C2/c space group and consisting of semi-oxalate chains, diprotonated beta-alanine dimers and water molecules bonded to both these units is confirmed. New results are obtained for distances in the carboxylic groups and hydrogen bonds. These structural observations are used for protonation degree monitoring on the carboxylic oxygen atoms. They are in accordance with our vibrational study. The 13C NMR spectra provide insights into the solid structure of this complex, character of its hydrogen bonds and the beta-alanine protonation.     

Hydrogen bonds in fluorosubstituted dicarboxylic acids: vibrational spectra and crystal structure of potassium hydrogen difluorofumarate and potassium hydrogen difluoromaleate

The crystal structures of potassium hydrogen difluoromaleate (KHDFM) and potassium hydrogen difluorofumarate (KHDFF) have been determined by single crystal X-ray methods. The hydrogen difluoromaleate ion has a closed ring structure with a short intramolecular hydrogen bond. The O· O distance is 2.415(1) Å The hydrogen difluorofumarate ions form infinite chains via short intermolecular hydrogen bonds.The O· ;O distance is 2.450(5) Å. In both compounds the hydrogen bonds are across crystallographic symmetry elements. The vibrational spectra of both compounds and their deuterated derivatives have been recorded and assigned. The IR spectrum of KHDFF is of Speakman's A₂ type. The spectra of KHDFM and potassium hydrogen maleate are very similar.     

dl‐Cysteinium semioxalate

Two chiral counterparts (l ‐ and d ‐cysteinium cations related by an inversion centre) are present in the structure of the title compound, C₃H₈NO₂S⁺·C₂HO₄⁻, with a 1:1 cation–anion ratio. The carboxy group of the cysteinium cation is protonated in the trans position relative to the amino group. The crystal structure is built up of double layers, in which dimers of cysteinium cations are connected to each other not directly, but via bridges of twisted semioxalate anions linked to each other via O—H...O hydrogen bonds forming infinite chains. An interesting feature of the crystal structure is the absence of either S—H...S or S—H...O hydrogen bonds.     

铜(Ⅱ)与2-吡啶酸、4,4′-联吡啶配合物的合成、结构和电化学性质(英文)

The complex [Cu(bipy)(pc)(H2O)(ClO4)]·H2O(1)(bipy:4,4'-bipyridine;Hpc:α-pyridine carboxylic acid) has been synthesized and characterized by single crystal X-ray diffraction method and elemental analysis.It crysrallizes in the Monoclinic space group P21/n.The crystal structure reveals that Cu(Ⅱ) centre adopts a pseudo octahedral geometry.Ligand 4,4'-bipyridine as a bridge coordinates to two different Cu(Ⅱ) center to form a onedimensional zigzag chain.One dimensional chains are linked by C-H…O hydrogen bonding interactions to form two-dimensional layer.Layers are connected by O…H-O hydrogen bond to generate three-dimensional structure.The cyclic voltametric behavior of complex 1 is also investigated.     

A novel Zn(II) complex based on 1H-1,2,3-benzotriazol-1-ylacetic acid and 1H-1,2,3-benzotriazole ligands: Synthesis, crystal structure, and photoluminescent property

A novel complex formulated as [Zn(HBTA)₂(L)₂] · 2H₂O (I), where HL = 1H-1,2,3-benzotriazol-l-ylacetic acid, HBTA = 1H-1,2,3-benzotriazole, has been synthesized and structurally characterized by single crystal X-ray diffraction. Complex I shows a mononuclear structure, which is assembled into 1D chain via intermolecular π…π interactions and N-H…O hydrogen bonds. Different chains are linked by C-H…O hydrogen bonds into 2D layer. The photoluminescence property of the complex has been investigated.     

Diguanidinium hydrogenarsenate monohydrate and its deuterated analogue vibrational, DSC and X-ray investigations

The crystal structure of diguanidinium hydrogenarsenate monohydrate has been found to belong to the P42(1)/c space group of the tetragonal system, with Z = 8, a = 17.114(2) A, c = 7.3500(10) A. In this complex, a network of hydrogen bonds links water molecules and hydrogenarsenate ions. The hydrogenarsenate ions form hydrogen-bonded chains along the crystallographic c-axis. Detailed vibrational studies have been carried out (FTIR and FT-Raman on powder samples, polarized FTIR microscope on a small single crystal at room temperature). The vibrational spectra are discussed in relation to the crystal structure. Calorimetric (DSC) studies have been performed, but no phase transition was found in the temperature range 100-350 K.     

以二亚乙基三胺为模板的链状结构硫酸钬配合物的合成、晶体结构及性质

通过溶剂热技术合成了一种以二亚乙基三胺(dien)为模板的链状结构硫酸钬(H₃dien)[Ho(SO₄)₃(H₂O)₂] (1),并通过X射线分析、红外光谱、元素分析和粉末衍射进行了表征。X射线晶体结构分析,化合物1结晶于单斜晶系,P2₁/c空间群,a=0.660 20(13) nm,b=1.476 7(3) nm,c=1.655 6(3)nm,β=93.313(2)°,V=1.611 4(5) nm³,Z=4。化合物1是由HoO₈多面体和SO₄四面体为建筑单元构建成新颖的单一链状结构。在a轴方向上,配位水分子通过氢键连接相邻的链形成三维超分子结构。有机胺分子镶嵌于链间,在合成化合物1合成过程中,pH值(pH=1.5)起了关键作用。     

Neutron powder‐profile study of chlorofluoromethane

The crystal structure of chloro­fluoro­methane, CH₂ClF, has been determined at 100 and 30 K using indexing, packing considerations and Rietveld refinement of neutron powder profiles. There is only one phase, in monoclinic space group P2₁ and with two mol­ecules in the unit cell occupying general positions. The structure has close packing in several directions and there are weak hydrogen bonds forming zigzag chains.     

Synthesis, crystal structure and magnetic properties of an alternating manganese chain

A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Mn(II) ions assemble in alternating chains with Mn-Mn distances of 3.8432(13) and 4.4428(14) Å. A 3D network of hydrogen bonds links the chains together. The temperature dependence of the magnetic susceptibility reveals that this compound undergoes a magnetic transition and exhibits an antiferromagnetic interaction in the low-temperature phase with two alternating exchange interactions of −2.32(1) and −5.55(1) cm⁻¹.     

Crystal structure and hydrogen-bonding system in cellulose Ibeta from synchrotron X-ray and neutron fiber diffraction

The crystal and molecular structure together with the hydrogen-bonding system in cellulose Ibeta has been determined using synchrotron and neutron diffraction data recorded from oriented fibrous samples prepared by aligning cellulose microcrystals from tunicin. These samples diffracted both synchrotron X-rays and neutrons to better than 1A resolution (>300 unique reflections; P2(1)). The X-ray data were used to determine the C and O atom positions. The resulting structure consisted of two parallel chains having slightly different conformations and organized in sheets packed in a "parallel-up" fashion, with all hydroxymethyl groups adopting the tg conformation. The positions of hydrogen atoms involved in hydrogen-bonding were determined from a Fourier-difference analysis using neutron diffraction data collected from hydrogenated and deuterated samples. The hydrogen atoms involved in the intramolecular O3...O5 hydrogen bonds have well-defined positions, whereas those corresponding to O2 and O6 covered a wider volume, indicative of multiple geometry with partial occupation. The observation of this disorder substantiates a recent infrared analysis and indicates that, despite their high crystallinity, crystals of cellulose Ibeta have an inherent disorganization of the intermolecular H-bond network that maintains the cellulose chains in sheets.     

2‐Ethyl‐6‐methylpyridin‐3‐ol and its salt bis(2‐ethyl‐3‐hydroxy‐6‐methylpyridinium) succinate

The title compounds, C₈H₁₁NO, (I), and 2C₈H₁₂NO⁺·C₄H₄O₄²⁻, (II), both crystallize in the monoclinic space group P2₁/c. In the crystal structure of (I), intermolecular O—H...N hydrogen bonds combine the molecules into polymeric chains extending along the c axis. The chains are linked by C—H...π interactions between the methylene H atoms and the pyridine rings into polymeric layers parallel to the ac plane. In the crystal structure of (II), the succinate anion lies on an inversion centre. Its carboxylate groups interact with the 2‐ethyl‐3‐hydroxy‐6‐methylpyridinium cations via intermolecular N—H...O hydrogen bonds with the pyridine ring H atoms and O—H...O hydrogen bonds with the hydroxy H atoms to form polymeric chains, which extend along the [01] direction and comprise R₄⁴(18) hydrogen‐bonded ring motifs. These chains are linked to form a three‐dimensional network through nonclassical C—H...O hydrogen bonds between the pyridine ring H atoms and the hydroxy‐group O atoms of neighbouring cations. π–π interactions between the pyridine rings and C—H...π interactions between the methylene H atoms of the succinate anion and the pyridine rings are also present in this network.     

Crystal Structure of 1,10-Diazonia-18-crown-6 Bis(DL-glutamate)

The crystal structure of 1'10-diazonia-18-crown-6 bis(DL-glutamate) was studied by single crystalX-ray diffraction. The geometries of molecular ions, their packing in the crystal lattice were determined.The macrocyclic dication is located around the crystallographic inversion center i(000) and has an unusual, previously unknown conformation. The crystalline salt forms an infinite three-dimensional polymeric network linked by interionic hydrogen bonds and coulombic interactions of molecular ions.     

3，5-二羟基-2，4，6-三硝基苯酚铷的晶体结构和热行为

0IntroductionSom e nitrogen鄄rich alkaline and alkali鄄earth m et鄄als com pounds of polynitro hydroxybenzenes can beused environm entally friendly prim ary explosives[1￣5].2,4,6鄄Trinitro鄄1,3,5鄄trihydroxybenzene(trinitrophloroglu鄄cinol,TNPG)belongs to a polynitro hydroxybenzeneand has been used in chem icalindustry as an ingredi鄄entfor prim ing com position,percussion caps and deto鄄nator form ulations[6].Therefore,in recent years,ithasbeen exploited to prepare a num ber of salts of ba…     

Synthesis and crystal structure of polymeric aqua (2,2′-bipyridine)(μ-isonicotinato)copper(II) nitrate dihydrate

The title complex has been prepared and its crystal structure determined by X-ray diffraction methods. The complex crystallizes in the monoclinic space group P2₁/c. Cu(II) assumes a square pyramidal coordination geometry, formed by two isonicotinate anions, a bipyridine ligand and a coordinated water molecule. Each isonicotinate bridges two Cu atoms through pyridine-N and carboxyl-O atoms, respectively, to form zigzag polymeric chains. Between the polymeric chains, aromatic stacking and hydrogen bonding are observed.     

The supramolecular architecture of tris(naphthalene‐1,5‐diaminium) bis(5‐aminonaphthalen‐1‐aminium) octakis[hydrogen (5‐carboxypyridin‐3‐yl)phosphonate]

The asymmetric unit of the title compound, 3C₁₀H₁₂N₂²⁺·2C₁₀H₁₁N₂⁺·8C₆H₅NO₅P⁻, contains one and a half naphthalene‐1,5‐diaminium cations, in which the half‐molecule has inversion symmetry, one 5‐aminonaphthalen‐1‐aminium cation and four hydrogen (5‐carboxypyridin‐3‐yl)phosphonate anions. The crystal structure is layered and consists of hydrogen‐bonded anionic monolayers between which the cations are arranged. The acid monoanions are organized into one‐dimensional chains along the [101] direction via hydrogen bonds established between the phosphonate sites. (C)O—H...N_py hydrogen bonds (py is pyridine) crosslink the chains to form an undulating (010) monolayer. The cations serve both to balance the charge of the anionic network and to connect neighbouring layers via multiple hydrogen bonds to form a three‐dimensional supramolecular architecture.     

Ring pucker in dihydroaromatic epoxides: The molecular structure ofr-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene

The crystal structure of the derivative of tetrahydronaphthalene with substituent epoxy, hydroxyl, and methyl groups in the more saturated ring (r-1-hydroxy-t-2-methyl-t,t-3,4-epoxy-1,2,3,4-tetrahydronaphthalene) has been determined. The hydroxyl and methyl groups are both found to beequatorial. The crystal structure is characterized by chains of molecules linked by O-H O hydrogen bonds involving the hydroxyl groups; these hydrogen bonds lie approximately parallel to theb axis. The conformations of the epoxide-bearing rings in various hydroxy epoxides are compared and shown to be similar.     

Alpha,beta-unsaturated ketoximes carrying a terminal pyridine or quinoline subunit as building blocks for supramolecular syntheses

[Structure: see text]. The crystal structures of a new series of alpha,beta-unsaturated ketoximes, 8-14, carrying the terminal 4-pyridinyl, 3-pyridinyl, or 4-quinolinyl subunit have been investigated by X-ray structural analysis. The dominating intermolecular interaction in all structures, except 11, is the head-tail OH...N hydrogen bond between the oxime moiety and the nitrogen atom of the heterocyclic unit. This intermolecular interaction generates infinite chains, which are cross-linked by CH...O/N/Cl or CH...pi interactions. Compound 10 has been shown to adopt a double-helical structure in the crystalline state. Compound 11 represents the only case where the unexpected head-head NOH...N(OH) hydrogen bonds determine the crystal packing. Both hydrogen-bonding and aromatic interactions stabilize the crystal structures of 8-14.