氨基甲酸酯型脱氧胆酸分子钳对氨基酸甲酯的手性识别 研究

以脱氧胆酸为spacer,通过三光气桥连各种芳胺,合成了新的氨基甲酸酯型分子钳受体1～4,这些化合物的结构经IR,^1HNMR和元素分析所证实。利用差光谱滴定法考察了其与D/L氨基酸甲酯的对映选择性识别性能。结果表明,分子钳1～4对所考察的氨基酸甲酯均具有识别能力,其对D-氨基酸甲酯的识别优于对L-氨基酸甲酯的识别。从主客体间的大小形状匹配及几何互补关系等方面对这些受体的识别能力及对映选择性进行了讨论。     

Oxidative polymerization of p-alkylphenols catalyzed by horseradish peroxidase

Enzymatic oxidative polymerization of p-alkylphenols using horseradish peroxidase as catalyst has been carried out in two polymerization solvent systems: a mixture of phosphate buffer (pH 7) and 1,4-dioxane, and a reverse micellar solution, yielding powdery polymeric materials. The polymer yield was much dependent upon the type of alkyl group in the monomer as well as the solvent type. In case of the polymerization of umbranched alkylphenols in the aqueous 1,4-dioxane, the polymer yield increased with increasing chain length of the alkyl group from 1 to 5, and the yield of the polymer from hexyl or heptylphenol was almost the same as that of the pentyl derivative. The relationship between the type of substituent and the polymer yield in the reverse micellar system was different from that in the aqueous 1,4-dioxane; the highest yield was achieved from ethylphenol. The resulting polymers had molecular weight of several thousands. The polymer was estimated to be composed from a mixture of phenylene and oxyphenylene units from IR analyses. TG measurement exhibited that the polymer had relatively high thermal stability. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1453–1459, 1997     

Crystal structure of the 2:1 inclusion compound between deoxycholic acid and quadricyclane

The 2:1 inclusion compound formed between deoxycholic acid (C₂₄H₄₀O₄,M _r=392.58) and quadricyclane (C₇H₈,M _r=92.14) crystallizes in space groupP2₁2₁2₁ witha=27.150(7),b=13.359(3),c=14.161(4) Å,Z=4. The structure was refined toR=0.08₆ andR _w=0.08₈ for 2079 observed reflections withI>2.5(I). The crystal packing is very similar to that found in the norbornadiene-deoxycholic acid inclusion compound and is characterized by an assembly of antiparallel pleated bilayers, formed by molecules of deoxycholic acid held together through hydrogen bonds. Quadricyclane occupies approximately the same position of norbornadiene and its atoms give rise to good van der Waals interactions with some methyl groups of deoxycholic acid. Supplementary Data relating to the article are deposited with the British Library as Supplementary Publication No. SUP 82006 (14) pages. To obtain copies, see page ii of this issue.     

Oxidative polymerization of acrylamide in the presence of thioglycolic acid

Chemical polymerization of acrylamide at room temperature was examined by using thioglycolic acid-cerium (IV) sulfate and thioglycolic acid-KMnO₄ redox systems in acid aqueous medium. Water soluble polyacrylamides containing thioglycolic acid end groups were synthesized. The effects of the molar ratio of acrylamide to Ce(IV) n _AAm /n _Ce(IV) , the polymerization time, the temperature, the monomer concentration, the molar ratio of cerium (IV) sulfate to thioglycolic acid and the concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. Lower molar ratios of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight of polymer. The increase of reaction temperature from 20 to 70°C resulted in a decrease in the yield but generally resulted in a constant value for the molecular weight of polymer. With increasing polymerization time, the yield and molecular weight of polymer did not change substantially. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions respectively in the polymerization reaction. The existence of Ce(III) ion bound to polymer was investigated by UV-visible spectrophotometry and fluoresce measurements. The amount of Mn(II) incorporated into the polymer was determined using graphite furnace atomic absorption spectrometry. The mechanism of this phenomenon is discussed.     

Oxidative polymerization of N-substituted carbazoles

Poly(N-vinylcarbazole), poly(N-carbazole) and poly(N-ethylcarbazole) powders were chemically synthesized by the reaction of ceric ammonium nitrate (CAN) with N-vinylcarbazole carbazole and N-ethylcarbazole in acetonitrile. Products were characterized by elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and viscosity, X-ray fluorescence and four-probe conductivity measurement. It is found that when a suitable concentration of CAN is used in the polymerization process, the conductivity of chemically synthesized polymers can be improved further by controlling the CAN addition. © 1997 John Wiley & Sons, Ltd.     

单手性臂脱氧胆酸分子钳的设计与微波合成

分子钳人工受体的研究已成为生物有机化学和超分子化学前沿领域的研究热点.钳型结构受体以其灵活的结构及易于将裂穴内功能团汇聚在受体与底物结合的活性部位上等特点,对于实现主客体形状、大小和功能互补特别有效.     

新型脱氧胆酸钳形阴离子受体的设计合成及其对阴离子的识别性能研究

具有对阴离子选择性识别的人工受体的设计合成是生物有机化学和超分子化学前沿富于挑战性的领域之一[1].在许多识别阴离子的人工受体化合物中,脲和硫脲衍生物是重要的中性受体化合物之一.     

Oxidative polymerization of phenylenediamines catalyzed by horseradish peroxidase

Ortho-, meta-, and para-phenylenediamines were polymerized using hydrogen peroxide as an oxidant and horseradish peroxidase as a catalyst in mixed solvents of 1,4-dioxane and water. The yield of the polymers was strongly dependent on solvent composition, and maximum yields were obtained at 15–30% 1,4-dioxane. The analysis of circular dichroic spectra of the enzyme suggested that enzyme structure was significantly modified at high 1,4-dioxane contents, which may be responsible for the decrease of catalytic activity of the enzyme. On the basis of IR and electronic spectra of the polymers, it was considered that o- and p-phenylenediamine polymers retain disubstituted benzene nuclei, which suggests that the polymerization proceeded mainly via N—N coupling. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2593–2600, 1998     

One-pot synthesis of network supported catalyst using supramolecular gel as template

<正>A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template.This procedure directly attaches ligand to support during fabricating the support.Using this strategy,supported CuBr/di-(2-picolyl) amine catalyst with U-shaped fibrillar network was prepared and used in atom transfer radical polymerization of methyl methacrylate.XPS and SEM characterization of the catalyst revealed homogeneous distribution of ligand,sufficient reactive sites,adequate mechanical strength and macroporosity.The polymerization results demonstrated high activity and reusability of such catalyst.This strategy might be extended to other supported catalysts used in column reactors.     

Inclusion polymerization of isoprene in deoxycholic acid

The radiation-induced polymerization of isoprene was made on its inclusion (or clathrate) complex with deoxycholic acid (DOCA) at 150 and 300 kGy. The microstructure of the resulting polyisoprene (PIP) was studied by FTIR spectroscopy and found fully comparable to that of PIP prepared by emulsion polymerization by a free radical initiator. Thus, the 1,4-trans content was found to be 48% and that of 1,4-cis units was 28% of the polymer structure; the remaining are being 1,2 and 3,4 units. The PIP irregular microstructure was justified in terms of monomer dynamics inside the DOCA channels. PIP from inclusion polymerization is fully amorphous as studied by differential thermal analysis (DTA) in comparison to an authentic sample of trans-1,4-polyisoprene, which instead has a crystalline melting point of 71.5 °C. The inclusion complex of PIP with DOCA (PIP@DOCA) shows a DTA melting point of 194.4 °C, 12.4 °C higher than the melting point of pure DOCA. PIP isolated from inclusion polymerization from DOCA and its complex PIP@DOCA was studied also by thermogravimetry (TGA) and differential thermogravimetry (DTG).Isoprene does not form inclusion complexes with urea and thiourea. When irradiated with these two compounds it produces an oily PIP oligomer whose microstructure was found by FTIR spectroscopy analogous to that of PIP prepared by emulsion polymerization by a free radical initiator.     

Self-assembled graphitic nanotubes from an amphiphilic hexabenzocoronene bearing thiol functionalities: Redox-mediated polymerization and depolymerization

A hexabenzocoronene derivative consisting of lipophilic dodecyl side chains and thioacetyl-appended hydrophilic oxyethylene chains was newly synthesized. The self-assembly of this hexabenzocoronene amphiphile in tetrahydrofuran gave a nanotubular object, for which the thioacetyl functionalities were located on the inner and outer surfaces. The removal of the acetyl group under alkaline conditions, followed by autoxidation, allowed the conversion of the noncovalent architecture into a covalently stabilized form via disulfide linkages. The resulting surface-polymerized nanotubes were completely insoluble in common organic solvents. Scanning and transmission electron microscopy showed that the tubular morphology mostly remained after the oxidative polymerization. Disulfide oligomers involved in the polymerized nanotubes were transformed into a thiol monomer upon reduction with dithiothreitol. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5120-5127, 2006     

脱氧胆酸手性分子钳的微波合成及其对中性分子的识别性能研究

在微波辐射条件下,以脱氧胆酸甲酯为间隔基,高产率合成了5个脱氧胆酸手性分子钳人工受体,其结构经IR,1HNMR,MS及元素分析确证。用差紫外光谱法测定了其对中性分子的识别性能。实验结果表明,这类分子钳人工受体对所考察的客体分子有良好的识别作用,主客体间形成1∶1型主客体配合物,受体5d对苯胺的结合常数高达14171.39 M-1。     

Nucleobase-induced supramolecular polymerization in the solid state

Supramolecular polymerization, that is, the self-assembly of polymer-like materials through the utilization of the noncovalent bond, has been a developing area of research over the last decade. In this article, we report the synthesis of nucleobase-terminated (N⁶-anisoyl-adenine and thymine) low-molecular-weight poly(tetrahydrofuran) macromonomers (<2000 g mol⁻¹). The adenine-derived supramolecular telechelic polymer self-assembled in the solid state to yield materials with film- and fiber-forming capabilities. This material was thermally reversible and exhibited a ceiling temperature, above which a drop in viscosity was observed and fibers could no longer be obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3589–3596, 2003     

Synthesis of polymers by template polymerization. I. Template polymerization of poly(methacrylic acid) with β‐cyclodextrin

A novel template monomer with multiple methacryloyl groups was synthesized with β‐cyclodextrin by the acetylation of primary hydroxyl groups and the esterification of secondary hydroxyl groups with methacrylic acid anhydride. The average number of methacryloyl groups in the monomer was 11. The radical polymerization of the monomer was carried out with the following initiators: α,α′‐azobisisobutylonitrile, H₂O₂? Fe²⁺ redox initiator, p‐xylyl‐N,N‐dimethyldithiocarbamate (XDC), and α‐bromo‐p‐xylyl‐N,N‐dimethyldithiocarbamate (BXDC). When the concentration of the monomer was less than 4.12 × 10^?3 M, polymerization was limited inside the molecule, and gelation of the system was hindered. For controlled radical photopolymerization with XDC and BXDC, the methacryloyl groups of the monomer were homogeneously polymerized, and poly(methacrylic acid) with a narrow molecular weight distribution was obtained by the hydrolysis of the polymerized products. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3539–3546, 2001     

Oxidative coupling polymerization of bishydrazide for the synthesis of poly(diacylhydrazine): Oxidative preparation of oxidatively degradable polymer

The oxidative coupling polymerization of bishydrazide is successfully performed to form poly(diacylhydrazine) (PDAH), which is an oxidatively degradable polymer. Oxone is an effective oxidant, and a mixture of an aprotic polar solvent, water, and acetonitrile or N,N‐dimethylacetamide is necessary as the solvent. On treatment of PDAH with sodium hypochlorite solution or hydrogen peroxide, the PDAH is rapidly oxidized and degraded to the corresponding dicarboxylic acid. When hydrogen peroxide is used as the oxidant, the addition of acetonitrile and potassium carbonate is necessary for effective degradation. PDAH exhibits high thermal stability in air and a high T_g value. No oxidation is observed in air. Thus, PDAH is an oxidatively degradable high‐performance polymer that is stable toward oxygen. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Biocatalytic hydrogels by template polymerization

Novel ionizable hydrogels were prepared from poly(acrylic acid) and dimethylaminoethyl methacrylate monomer employing template polymerization technique as an alternative to traditional physical and chemical crosslinking. The mode of interaction, as proved by Fourier Transform Infrared Spectroscopy (FTIR), was multiple H‐bonding between the tertiary amino group of the monomer and the carboxylic groups of the polymer. The hydrogels represented suitable matrices for enzyme immobilization. The effect of varying the polymer–monomer molar ratio on the swelling kinetics and parameters was investigated. The dynamic swelling isotherm exhibited a Fickian mode of penetrant sorption and a plateau that increases with the amino group content. A polymer complex of molar ratio (polymer:monomer) 0.5:0.8 had a weight swelling ratio of 10 and 7 at pHs 3 and 8, respectively. The proven pH sensitivity together with the amphoteric character of these hydrogels make them good candidates for another bioapplication such as oral delivery systems of therapeutic peptides and proteins. The structural integrity of the hydrogels was proved by their swelling reversibility. β‐Galactosidase, as an acidic model enzyme, was immobilized covalently on the synthesized hydrogels. The maximum enzyme velocity (V_max) was enhanced to 19 µmol/min/mg, for polycomplex of molar ratio 0.5:0.8, compared with 3.2 µmol/min/mg for the free enzyme. Copyright © 2008 John Wiley & Sons, Ltd.     

Oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with dinuclear‐type copper(II) catalyst

The oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with the novel dinuclear‐type copper(II) catalysts successfully produced poly(2,3‐dihydroxy‐1,4‐naphthylene). For example, the MeOH‐insoluble polymer with a number average molecular weight of 4.4 × 10³ from the polymerization using the complex of CuCl₂ and N,N′‐bis(2‐morpholinoethyl)‐p‐xylylenediamine ( p ‐ 1 ) at room temperature under an O₂ atmosphere followed by acetylation of the hydroxyl groups was obtained in 63% yield. The structures of the tetraamine ligands and the counter anion of the copper(II) salts significantly influenced the catalyst activity. The polymerization of 2,2′‐dimethoxy‐1,1′‐binaphthalene‐3,3′‐diol with the 2CuCl₂‐ p ‐ 1 catalyst, however, resulted in a lower yield. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1635–1640, 2005     

Inclusion polymerization of 1-chlorobutadiene in a deoxycholic acid canal

Inclusion polymerization of 1-chlorobutadiene was studied using 3α,12α-dihydroxy-5β-cholan-24-oic acid (deoxycholic acid, DCA) as host molecules. It was found that the poly(1-chlorobutadiene) had almost 100% of head to tail, trans-1,4-structure on the basis of ¹³C-NMR and IR spectroscopies. This was the first example of preparing the highly regulated poly(1-chlorobutadiene) by using the inclusion polymerization technique. The polymers obtained were optically active and the maximum value of specific rotation was [α]_D-41.9°. Both the rate constants and the value of activation energy of the elementary reactions of inclusion polymerization of 1-chlorobutadiene were determined by graphical evaluation. The activation energy of propagation and termination was 11.7 and 11.1 kcal/mol, respectively.     

Synthesis of polyphenylacetylene by radiation-induced polymerization in deoxycholic acid clathrate

Phenylacetylene was polymerized as inclusion compound (clathrate) inside deoxycholic acid (DOCA) crystals. The polymerization was initiated by γ radiation and a total dose of 320 kGy was employed. The resulting polyphenylacetylene (PPA) was isolated by dissolution of deoxycholic acid in boiling ethanol. PPA high polymer was accompanied by a series of phenylacetylene oligomers, which were detected by liquid chromatographic analysis (HPLC). PPA was characterized by electronic absorption spectroscopy and by FT-IR spectroscopy in comparison to a reference PPA prepared by a stereospecific catalyst. The microstructure of PPA from inclusion polymerization was highly trans type, similar to that observed on PPA prepared by bulk radiolysis. No optical activity was detected by polarimetry on PPA prepared by inclusion polymerization.The host–guest complex PPA/DOCA was studied by differential thermal analysis (DTA) and by thermogravimetry (TGA). DTA provided evidences of the host–guest complex formation from the shift of the melting point of DOCA while the TGA confirmed the identity – in terms of thermal behaviour – of the PPA from inclusion polymerization with that from stereospecific polymerization.     

Acrylic acid polymerization kinetics

The kinetics of the isothermal polymerization of acrylic acid were determined utilizing ¹H-NMR spectroscopy. The polymerization rate was observed to depend approximately on the $ \frac{3}{2} $ power of monomer and the $ \frac{1}{2} $ power of sodium persulfate concentration. This is consistent with a model in which the rate of initiation is itself dependent on the monomer concentration. The polymerization rate was also observed to have a strong dependence on percent neutralization, decreasing with increasing level of neutralization up to 75 to 100% neutralization, and then increasing again. The activation energy for the rate of polymerization was between 9 and 13 kcal/mol except for 100% neutralized acrylic acid, which had an activation energy of 18 kcal/mol. These data suggest that a transition in mechanism occurred at 100% neutralization. Increasing the ionic strength by the addition of sodium chloride also increased the rate. The dependence of the molecular weight on the above variables was also quantified for use in the model. It decreased with increasing conversion, decreasing ionic strength and increasing initiator. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2029–2047, 1997