Novel polymer nanocomposite hydrogel with natural clay nanotubes

Polymer nanocomposite gels (NC gels), a kind of typical soft materials, can be synthesized through free-radical polymerization of water-soluble monomers in the presence of nanoclay in aqueous system. Here, novel natural tube-like nanoparticles, halloysite nanotubes (HNTs), are firstly used as multifunctional cross-linkers for polyacrylamide (PAAm) to form a new type of organic/inorganic hybrid hydrogels. Significant improvements in mechanical properties of the PAAm-HNTs NC gels are found by the addition of HNTs as shown by the static mechanical testing and dynamic viscoelasticity measurement. HNTs are uniformly dispersed in the NC gels from the morphological result. HNTs can be intercalated by PAAm chains as observed by the X-ray diffraction result. Hydrogen bonding interactions between HNTs and PAAm are confirmed by the infrared spectroscopy and X-ray photoelectron spectroscopy. The maximum equilibrium degree of swelling (EDS) for the NC gel is 4000% and the EDS decreases with the concentration of clay nanotubes. The present work provides a novel routine for preparing NC gels using “green” one-dimensional nanoparticle. The prepared NC gels have promising application in biomedical areas due to the superior mechanical properties of the gels and good biocompatibility of HNTs.     

Two-component hydrogels comprising fatty acids and amines: structure, properties, and application as a template for the synthesis of metal nanoparticles

Stearic acid or eicosanoic acid mixed with di- or oligomeric amines in specific molar ratios form stable gels in water. The formation of such hydrogels depends on the hydrophobicity of the fatty acid, and also on the type of amine used. The gelation properties of these two-component systems were investigated using electron microscopy, FTIR spectroscopy, 1H NMR spectroscopy, differential scanning calorimetry (DSC), and both single-crystal and cast-film X-ray diffraction. Results of FTIR spectral analysis suggest salt formation during gelation. 1H NMR analysis of the gels indicates that the fatty acid chains are immobilized in the gel state and when the gel melts, these chains regain their mobility. Analysis of DSC data indicates that increase in the spacer length in the di-/oligomeric amine lowers the gel-melting temperature. Two of these gelator salts developed into crystals and structural details of such systems could be secured by single-crystal X-ray diffraction analysis. The structural information of the salts thus obtained was compared with the XRD data of the self-supporting films of those gels. Such analyses provided pertinent structural insight into the supramolecular interactions that prevail within these gelator assemblies. Analysis of the crystal structure confirmed that multilayered lamellar aggregates exist in the gel and it also showed that the three-dimensional ordering observed in the crystalline phase is retained in only one direction in the gel state. Finally, the hydrogel was used as a medium for the synthesis of silver nanoparticles. The nanoparticles were found to position themselves on the fibers and produced a long, ordered assembly of gel-nanoparticle composite.     

Synthesis, Structure and Characterization of Manganese(Ⅱ) Coordination Polymer with Camphoric Acid and 1,10-Phenanthroline

A novel coordination polymer, Mn(H2O)(CA)(Phen)·H2O(CA=camphoric acid, Phen=1,10-phenanthroline), was synthesized and its crystal structure was determined by single crystal X-ray diffraction. Six-coordinated Mn(Ⅱ) atoms are linked with carboxyl groups from camphoric acid ligands to form infinite one-dimensional chains. These chains are packed by means of hydrogen bonding and π-π stacking, forming a three-dimensional structure. IR, thermogravimetric analysis and magnetic susceptibility data for Mn(H2O)(CA)(Phen)·H2O are given.     

Closed-pore crystal capable of adsorbing CO2 onto isolated cavities generated by disorderly mixing of substituents on host skeleton

A single crystal adsorbent, [Rh(II)(2)(bza)(4)(2,3-empyz)](n) (2,3-empyz = 2-ethyl-3-methylpyrazine) (1), was synthesized by self-assembly reaction of a Rh(2) benzoate complex and substituted pyrazine linker. The compound consists of one-dimensional zigzag chains, which generated a closed-pore structure without channels. The cavities were statistically generated by the static disorder of substituents on pyrazine and are separated by long intervals within the crystal. The property of CO(2) absorption was characterized in this closed-pore system. The CO(2) inclusion structure was determined by single-crystal X-ray diffraction measurements. These studies suggest that CO(2) molecules were adsorbed and diffused in the nonporous crystal with the isolated cavities.     

一个新的噻二唑衍生物H2ADTZ与锰的二维聚合物的合成与晶体结构(英)

A new 1,3,4 thiadiazole-derivative ligand 2,5-(s-acetic acid) dimercapto-1,3,4 thiadiazole (H₂ADTZ) and its one-dimensional manganese polymer Mn(ADTZ)·4H₂O had been synthesized and structurally characterized by X-ray single crystal diffraction in this paper. The Mn(Ⅱ) ion is coordinated with a distorted octahedron by two oxygen atoms from neighboring two deprotonated ligands ADTZ^2- and other four oxygen atoms from four coordinated water molecules. The structural feature of the title compound is the formation of one-dimensional manganese chains polymer through the bridging of dioxygen O-O units. In the solid state structure of the complex, one-dimensional manganese chains are joined together by the weak intermolecular hydrogen bonds and vander Waals interactions forming a two-dimensional supramolecular compound. Furthermore, the UV spectra and electro-chemical properties of the title compound were also investigated. CCDC: 260532.     

Crystal Structure and Property Research on Compounds Co（Ⅱ） and Zn（Ⅱ） with 3-Methylbenzoic Acid

Two compounds with 3-methylbenzoic acid(HL) [Co(L)2(4,4'-bipy)]n 1 and [Zn2(L)4(4,4'-bipy)]n 2(L = 3-methylbenzoic acid) have been hydrothermally synthesized directly and characterized by single-crystal X-ray diffraction analysis,elemental analyses,IR spectra and ultraviolet-visible diffuse reflection integral spectra(UV-Vis DRIS).The two compounds are both one-dimensional infinite chains.The structural difference is that 1 is a double-chain structure and 2 is only a single chain one.At the same time,the carboxylate groups adopt different modes in the two compounds,relatively.Additionally,in order to explore the structural characteristic,two-dimen-sional IR spectra are investigated for 1 and 2.Photo-luminescent property of 2 is also researched in detail.     

ORDERED STRUCTURAL EVOLUTION AND RELAXATION BEHAVIORS OF A SERIES MICROPHASE SEPARATED “HAIRY-ROD” POLYIMIDES WITH MULTIPLE ALKYL SIDE CHAINS

A series of “hairy-rod” polyimides, BBPA(n), with multiple alkyl side chains was prepared from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-biphenyldiamine substituted in the 2,2′-positions with benzoate, which was substituted in the 3,4,5-positions with ether side chains of varying lengths. The number of the methylene units, n, in these alkyl side chains were in even numbers ranging from 8 to 18. Combining techniques of one-dimensional (1D) and 2D wide angle x-ray diffraction, 1D small angle X-ray scattering, differential scanning calorimetry experiments, it was found that this series of “hairy-rod” polyimides possess a micro-phase separation between the backbones and side chains. This led to the formation of ordered structures in two different length scales, of which both are hexagonal packing: one is attributed to the alkyl side chains on the sub-nanometer scale, and another is for the whole polymer chains on the nanometer scale. The development of the hexagonal structure on the sub-nanometer scale was critically dependent upon the lengths of the alkylside chains. Three relaxation processes were captured by dynamic mechanical analysis, i.e., segmental motion of the backbones, α the melting of the side chain crystals, β1, which exits only for the materials with longer side chains(n=18,16); and the subglass relaxation of side chains, β2- The peak relaxation temperature of the α process decreased with increasing the length of side chains, while the one of the β2 process increased. The activation energy of the α relaxation was relatively independent on the length of side chain, whereas, β2 process showed the increasing of activation energy with increasing the length of side chains.     

One-dimensional Infinite Chain Organotin Compounds: Synthesis and Structural Characterization of Triphenyltin Thiazole-2-carboxylate and Triphenyltin 3-Pyridinylcarboxylate

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配位聚合物[Ni(Hsal)2(Py)2]n(Hsal=水杨酸根,Py=吡啶)的合成,表征和晶体结构

用水杨酸和吡啶与Ni(ClO4)26H2O 合成了一个新颖配位聚合物[Ni(Hsal)2(Py)2]n。对配合物进行了X射线衍射结构表征, C24H20N2NiO6, Mr = 491.13, 晶体属三斜晶系, P 空间群, 晶胞参数: a = 7.372(2), b =10.852(2), c = 14.728(3) ? a = 108.36(3), b = 93.83(3), g = 103.67(3), V = 1073.7(4) ?。F(000) = 508, m = 0.949mm-1, Z = 2, Dc = 1.519 g/cm3。最后修正到R = 0.0390, wR = 0.0772。配合物中Ni为五配位, 呈四方锥构型。配合物中2个水杨酸根的配位方式不一样, 其中一个水杨酸根作为双齿桥连配体, 使配合物呈一维链状结构。水杨酸苯环的-堆积作用和分子间的氢键作用, 又使配合物呈二维网络结构。     

Molecular mechanism of physical gelation of hydrocarbons by fatty acid amides of natural amino acids

A variety of fatty acid amides of different naturally occurring l-amino acids have been synthesized and they are found to form gels with various hydrocarbons. The gelation properties of these compounds were studied by a number of physical methods including FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rheology, and it was found that gelation depended critically on the fatty acid chain length and the nature of the amino acid. Among them l-alanine based gelators were found to be the most efficient and versatile gelators as they self-assemble into a layered structure to form the gel network. Mechanisms for the assembly and formation of gels from these molecules are discussed.     

Etude par diffraction des rayons X des gels de polysavons derivant du copolymere alterne anhydride maleique-hexadecylvinylether

Low and wide angle X-ray diffraction was used to study the structural behaviour at low temperature of aqueous gels of an alternating copolymer of maleic anhydride with hexadecyl vinyl ether characterized at high temperatures by either a lamellar structure or a cylindrical structure. This study has shown the importance at low temperature of the crystallization of the paraffin chains. Only the lamellar structure can be observed. In this structure, both polymer skeletons and paraffin chains are assigned to be regularly arranged in space, the former at the interfaces, the latter inside the lamella.     

Poly(L-lysine) containing azobenzene units in the side chains: influence of the degree of substitution on liquid crystalline structure and thermotropic behaviour

The structure of poly(L-lysine)s containing between 20% and 100% of azobenzene units in the side chains has been studied by X-ray diffraction, between room temperature and 250 C. Except for samples having very low contents of azobenzene, the polymers are found to exhibit mesomorphic structures of the smectic A1 type deriving from the beta -structure of polypeptides. For polymers in which all lysine residues were substituted, the polypeptide main chains are arranged in layers corresponding to the sheets of a polypeptide 'antiparallel' beta -structure, and the side chains are perpendicular to the smectic layers. For polymers containing both substituted and free lysine side chains, each smectic layer results from the superposition of two layers: one layer contains the free lysine side chains; the other contains the azobenzenemodified lysine side chains and the polypeptide main chains that are arranged in 'antiparallel' beta -structures. All polymers exhibit only one smectic A mesophase as a function of temperature. The thickness of the smectic layers increases with increasing temperature until a thickness is reached that corresponds to the maximum interaction between the azobenzene mesogens in their trans -configuration.     

Preparing and physicochemical properties of microcrystalline polyacrylic acid gels

The facile synthesis of microcrystalline polyacrylic acid (PAA) gels via emulsion polymerization is presented and the effects of experimental factors that determine the microcrystallization of PAA microgels were investigated. Both reaction temperature and emulsifier type play important roles in the crystallization of PAA microgels. Selected-area electron diffraction and X-ray diffraction patterns show that the PAA microgels formed using sodium dodecyl sulfate as emulsifier are single-crystallized, and low reaction temperature favors the formation of the PAA microgels with high crystallinity. Controlling the reaction temperature may also improve morphology controllability by emulsion polymerization in synthesizing microcrystalline PAA gels. In addition, the microcrystalline PAA gels exhibit good Young’s modulus, which is 7.8 times higher than that of the PAA microgels.     

Self-assembly of dialkyltin moieties and mercaptobenzoic acid into macrocyclic complexes with hydrophobic "pseudo-cage" or double-cavity structures: supramolecular infrastructures involving intermolecular C-H...S weak hydrogen bonds and pi-pi interactions

Four novel organotin complexes of two types--[R2Sn(o-SC6H4CO2)]6 (R = Me, 1 x H2O; nBu, 2) and {[R2Sn(m-CO2C6H4S)R2Sn(m-SC6H4CO2)SnR2]O}2 (R = Me, 3; nBu, 4)--have been prepared by treatment of o- or m-mercaptobenzoic acid and the corresponding R2SnCl2 (R = Me, nBu) with sodium ethoxide in ethanol (95%). All the complexes were characterized by elemental analysis, FT-IR and NMR (1H, (3C, 119Sn) spectroscopy, TGA, and X-ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic "pseudo-cage" structures, while 3 and 4 are hexanuclear macrocycles with double-cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1-4, which exist either as one-dimensional chains of rings or as two-dimensional networks assembled from the organometallic subunits through intermolecular C-H...S weak hydrogen bonds (WHBs) and pi-pi interactions.     

A new high pressure phase of sodium formate dihydrate; an experimental and computational study

As part of an on-going programme to study the high pressure structural behaviour of hydrated small molecular systems, sodium formate dihydrate has been studied using high pressure single crystal X-ray and neutron powder diffraction methods. A new phase was initially identified at 17 kbar by X-ray diffraction and high level quantum mechanical calculations completed the structure, allowing definitive hydrogen atom positioning. The resulting structure compared favourably with that found subsequently by high pressure neutron diffraction. The neutron diffraction study also revealed that the deuterated form, NaDCO(2).2D(2)O, is stable in a different structural form to that of the non-deuterated material at ambient pressure. The structure of this phase is related to that of the high pressure phase via a simple translation of the molecular layers.     

Structure, spectral and luminescence properties of compounds of europium(III) with nicotinic acid and enrofloxacin

The compounds of Eu(III) with nicotinic acid and enrofloxacin are synthesized. Their composition and structure are proved by the data of elemental analysis, IR and luminescence spectroscopy, powder and single crystal X-ray diffraction. By single crystal X-ray diffraction, the structure of the compound of Eu with nicotinic acid is identified as a centrosymmetric dimer with 4 carboxylate bridges of the composition Eu₂(C₆H₄NO₂)₆·4H₂O. The Stark structure of the ⁵ D ₀-⁷ F _j transitions in the mixed-ligand compounds of Eu(III) with nicotinic acid and enrofloxacin is determined. The bands of IR spectra are assigned; the conclusion about the bidentate coordination of ligands is made.     

A one-dimensional Mn(II)-based metal organic oxide: structure and properties

A one-dimensional metal organic oxide of Mn(II), with formula [Mn₃(OH)₂(Hpdc)₂]_n (H₃pdc = 3,5-pyrazoledicarboxylic acid), was prepared via the hydrothermal method and its structure solved by single-crystal X-ray diffraction. The compound exhibits a three-dimensional framework structure, comprising three crystallographically unique Mn atoms bridged by OH ligands (O9 and O10) and O atoms from the Hpdc ligands, forming one-dimensional metal–organic oxide chains. Two kinds of magnetic exchange are observed: a strong antiferromagnetic intra-chain interaction, arising from the short distance between Mn(II) centers, and a ferromagnetic inter-chain interaction, due to the larger distances between the chains. The compound shows good photocatalytic activity for the decomposition of methylene blue in aqueous medium under simulated sunlight.     

Open metal-organic framework containing cuprate chains

A three-dimensional Cu(II) metal-organic framework, copper hydroxide p-pyridinecarboxylate hydrate, [Cu(OH)(C5H4NCO2).H2O], was synthesized by hydrothermally reacting copper nitrate with p-pyridinecarboxylic acid. The crystals were suitable for single-crystal X-ray diffraction analysis, which showed that the Cu(II) centers adopt a slightly distorted square pyramidal geometry. They coordinate to both the pyridyl and carboxylate functionalities of the pyridinecarboxylate bridging ligands. Infinite copper oxide chains run through the structure and are connected by p-pyridinecarboxylate (p-PyC) ligands. Crystal data: monoclinic, space group P2(1)/n, a = 3.5521(2) A, b = 15.8665(11) A, c = 12.9977(9) A, beta = 95.285(2) degrees , and Z = 4. Thermogravimetric analysis (TGA) revealed that the guest H2O molecules in the channels may be removed, and the material is stable to ca. 245 degrees C. Magnetic measurements indicated the material has one-dimensional (1D) antiferromagnetic ordering within the Cu2+ chains with a Néel temperature of ca. 51 K. Data fitting to the Bonner-Fisher model yielded a coupling constant, J, of -7.3 cm(-1) and g factor of 2.15. The Curie tail below 20 K is due to a small amount of paramagnetic impurities, calculated to be approximately 0.2% in concentration. Further characterization of crystallinity and morphology are discussed, including powder X-ray diffraction (PXRD), elemental analysis, and optical microscopy.     

Impact on the mesophase transition temperatures of 1,4-bis(naphthyl)-1,3-butadiyne of the attachment of terminal alkoxy chains

The synthesis of 1,4-bis(2-naphthyl)-1,3-butadiynes, containing terminal alkoxy chains, is reported. The mesomorphism of these compounds has been characterized by differential scanning calorimetry and polarizing optical microscopy. The introduction of terminal alkoxy chains, significantly lowers the melting temperature of the analogous core without terminal chains. The induction of a smectic phase occurred when two decyloxy chains were attached. The solid state structures and packing arrangements of the butyloxy derivative and the chainless core were determined by single crystal X-ray diffraction, and revealed greater layer interpenetration for the substituted material.     

Inclusion Complexes of ß-Cyclodextrin and Its Silyl Derivative with Some Pharmacologically Important Aromatic Monocarboxylic Acids

Stable host-guest complexes of ä-cyclodextrin and its silyl derivative with some aromatic monocarboxylic acids of pharmacological interest were prepared. The structure of the ä-cyclodextrin complex with nicotinic acid was studied by X-ray diffraction.