MISCIBILITY, MICROSTRUCTURE, AND DYNAMICS OF BLENDS CONTAINING BLOCK-COPOLYMER .1. MISCIBILITY OF BLENDS OF HOMOPOLYSTYRENE WITH STYRENE-BUTADIENE BLOCK-COPOLYMERS

The miscibilities of blends of homopolystyrene/styrene-butadiene/styrene (PS/SBS) and PS/SB-4A (4-arm star block copolymer) have been studied by dynamic mechanical analysis (DMA) and C-13 CPMAS NMR techniques. The results indicate that the miscibilities o

THE CLEAVAGE REACTION OF THE MO-MO TRIPLE BOND - THE CRYSTAL-STRUCTURES OF MOLYBDENUM COMPLEXES [CPMO(CO)(2)(C(5)H(4)NS)], [CPMO(CO)(2)(C(9)H(6)NS)]O=PPH(3) AND [CPMO(CO)(2)(S(2)CNME(2)]

The reactions of [Cp2Mo2(CO)4] (1) with 2,2'-dipyridyl disulphide (C5H4NS-)2, 8,8'-diquinolyl disulphide (C9H6NS-)2 and tetramethyl thiuram disulphide (Me2NC(S)S-)2 in toluene solution resulted in the cleavage of the Mo-Mo triple bond to yield molybdenum complexes [CpMo(CO)2(C5H4NS)] (2), [CpMo(CO)2(C9H6NS)] (3) and [CpMo(CO)2(S2CNMe2)] (4), respectively. The molecular structures of 2, 3 . O=PPh3 and 4 were determined by X-ray diffraction studies. Crystals of 2 are monoclinic, space group P2(1)/n, with Z = 4, in a unit cell of dimensions a = 6.448(1), b = 12.616(2), c = 14.772(2) angstrom, beta = 92.85(1)-degrees. The structure was refined to R = 0.028 and R(w) = 0.039 for 1357 observed reflections. Crystals of 3 . O=PPh3 are triclinic, space group P1BAR, with Z = 2, in a unit cell of dimensions a = 11.351(3), b = 13.409(3), c = 9.895(2) angstrom, alpha = 94.59(2), beta = 90.35(2), gamma = 78.07(2)-degrees. The structure was refined to R = 0.033 and R(w) = 0.037 for 3260 observed reflections. Crystals of 4 are monoclinic, space group P2(1)/a and Z = 4 with a = 12.468(5), b = 7.637(2), c = 13.135(4) angstrom, beta = 96.62(3). The structure was refined to R = 0.032 and R(w) = 0.042 for 1698 observed reflections. Each of complexes 2-4 contains a cyclopentadienyl ligand, a cis pair of carbonyls and a chelate ligand (S,N donor or S,S donor). All the compounds have distorted square-pyramid structures.

SYNTHESIS AND MOLECULAR-STRUCTURE OF NBU2[(MEO)3C6H2C(O)N2CHC6H4O]SN FORMED IN THE REACTION OF DI-N-BUTYLTIN(IV) OXIDE WITH 3,4,5-TRIMETHOXY-BENZOYL SALICYLAHYDRAZONE

The title complex was synthesized and characterized by H-1, C-13, Sn-119 NMR and IR spectra. A single crystal X-ray diffraction study confirmed its molecular structure and revealed that 3,4,5-trimethoxy-benzoyl salicylahydrazone was a tridentate and approximately planar ligand. The complex crystallizes in the triclinic space group P1BAR with a = 9.208(3), b = 12.536(2), c = 12.187(4) angstrom, alpha = 113.12(2), beta = 90.58(2), gamma = 81.42(2), V = 1277.5(6) angstrom, Z = 2. The structure was refined to R = 0.033 and R(w) = 0.041 for 3944 observed independent reflections. The tin atom has a distorted trigonal bipyramidal coordination. The Sn-C bond lengths are 2.129(5) and 2.113(5) angstrom (av. 2.121(5) angstrom), the C-Sn-C angle is 123.3(2); the bond length between the tin atom and the chelating nitrogen is 2.173(3) angstrom. Two chain carbon atoms and the chelating nitrogen atom occupy the basal plane. The skeleton of two erect oxygen atoms and the tin atom is bent (O-Sn-O angle = 153.5(1)). In the complex, the ligand exists in the enol-form.

取代基效应(SCS)与乙烯—α—烯烃共聚物的序列结构——Ⅱ.取代基效应方法

本文提出了一种解析乙烯-α-烯烃共聚物的~(13)C NMR谱的取代基效应方法,它揭示了存在于共聚物序列结构与~(13)C谱之间的对应关系,并对这种关系进行了系统的阐述。文章中首次按上述对应关系明显与否将共聚物~(13)C谱分成两类,并给出进行分类的三种判据:SCS参数,共单体均聚物的~(13)C谱,以及取代基的电性。文章最后比较了取代基效应方法与Grant-Paul方法的异同。

模式识别在有机化合物碳—13核磁共振波谱中的应用

本文介绍了以碳—13 NMR 谱为基础,运用模式识别方法对于取代苯类有机化合物的分类情况。数据源为 CIAC-碳-13数据库。特征选择为简单的机率比率法。模式识别方法为Fisher 意义下的判别函数、KNN 及非线性映射。所得结果比较满意。

Chaetopyranin, a benzaldehyde derivative, and other related metabolites from Chaetomium globosum, an endophytic fungus derived from the marine red alga Polysiphonia urceolata

Cultivation of the endophytic fungus Chaetomium globosum, which was isolated from the inner tissue of the marine red alga Polysiphonia urceolata, resulted in the isolation of chaetopyranin (1), a new benzaldehyde secondary metabolite. Ten known compounds were also isolated, including two benzaldehyde congeners, 2-(2 ',3-epoxy-1 ',3 '-heptadienyl)-6-hydroxy- 5-(3-methyl-2-butenyl) benzaldehyde (2) and isotetrahydroauroglaucin (3), two anthraquinone derivatives, erythroglaucin (4) and parietin (5), five asperentin derivatives including asperentin ( 6, also known as cladosporin), 5 '-hydroxy-asperentin-8-methylether (7), asperentin-8-methyl ether (8), 4 '-hydroxyasperentin (9), and 5 '-hydroxyasperentin (10), and the prenylated diketopiperazine congener neoechinulin A (11). The structures of these compounds were determined on the basis of their spectroscopic data analysis (H-1, C-13, H-1-H-1 COSY, HMQC, and HMBC NMR, as well as low- and high-resolution mass experiments). To our knowledge, compound 1 represents the first example of a 2H-benzopyran derivative of marine algal-derived fungi as well as of the fungal genus Chaetomium. Each isolate was tested for its DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging property. Compounds 1-4 were found to have moderate activity. Chaetopyranin (1) also exhibited moderate to weak cytotoxic activity toward several tumor cell lines.

Synthesis of titanium silicalites in different template systems and their catalytic performance

Titanium silicalites have been synthesized in the TPABr+ammonia, TPABr+hexanediamine, TPABr+ethylenediamine, TPABr+diethylamine, TPABr+TEAOH, TPABr+n-butylamine, TPABr+TBAOH and TBAOH+n-butylamine systems. As-synthesized titanium silicalites were characterized by XRD, IR and C-13 CP MAS NMR. Catalytic performance in epoxidation of propylene and template effect was investigated. It has been shown that both TPABr and TBAOH serve as templating agent in TPABr+TBAOH system. But in other systems, when there is enough TPABr, organic amines or ammoniums only act as the bases. TEAOH or n-butylamine can take the role of template when less TPABr is added. It indicates that the ability of organic amines or ammoniums to direct the Pentasil structure decreases as follows: TPA(+)>TBA(+)>TEA(+)>n-butylamine. Catalysts exhibiting good performance in epoxidation of propylene can be attained using TPABr as the template and ammonia, n-butylamine, diethylamine, hexanediamine or TBAOH as bases. (C) 1999 Elsevier Science B.V. All rights reserved.

Highly ordered periodic mesoporous ethanesilica synthesized under neutral conditions

Highly ordered mesoporous ethanesilica (MES) with 2D hexagonal structure was synthesized from 1,2-bis(trimethoxysilyl) ethane under neutral conditions for the first time. Divalent salts, such as NiCl2, MgCl2, ZnCl2, ZnSO4 and Zn(NO3)(2), were used to help the formation of the ordered mesostructure. The MES samples were characterized by powder X-ray diffraction, nitrogen sorption, transmission electron microscopy, FT-IR, C-13 and Si-29 solid-state NMR and thermal gravimetric analysis. A phase transition from a disordered wormhole-like structure to an ordered P6mm structure was observed upon the addition of inorganic salts. The pore size of the MES decreases from 4.7 to 3.9 nm with increasing content of the inorganic salts. Fluoride was also found to be important for the formation of ordered MES under neutral conditions.

Structural relation properties of hydrothermally stable functionalized mesoporous organosilicas and catalysis

The surfactant assistant syntheses of sulfonic acid functionalized periodic mesoporous organosilicas with large pores are reported. A one-step condensation of tetramethoxysilane (TMOS) with 1,2-bis(trimethoxysilyi)ethane (BTME) and 3-mercaptopropyltrimethoxysilane (MPTMS) in highly acidic medium was performed in the presence of triblock copolymer Pluronic P123 and inorganic salt as additive. During the condensation process, thiol (-SH) group was in situ oxidized to sulfonic acid (-SO3H) by hydrogen peroxide (30 wt % H2O2). X-ray diffraction studies along with nitrogen and water sorption analyses reveal the formation of stable, highly hydrophobic, and well-ordered hexagonal mesoscopic structures in a wide range of -CH2CH2-concentrations in the mesoporous framework. The resultant materials were also investigated by Si-29 MAS and C-13 CP MAS NMR, thermogravimetric analyses, UV-Raman spectroscopy, and FT-IR spectroscopy. The role of the bridged organic group on the hydrothermal stability of the mesoporous materials was established, which revealed an enhancement in hydrothermal stability of the materials with incorporation of the bridged organic groups in the network. The catalytic performance of -SO3H functionalized mesoporous materials was investigated in the esterification of ethanol with acetic acid, and the results demonstrate that the ethane groups incorporated in the mesoporous framework have a positive influence on the catalytic behavior of the materials.

Synthesis and structural characterization of (pyrazolyl)alkenyl Fischer carbene complexes of chromium and tungsten

Michael addition of substituted pyrazoles 2 to 1-alkynyl Fischer carbene complexes (CO)(5)M=C(OEt)(CdropCPh) (1) (a, M = Cr and b M = W) afforded (pyrazolyl)alkenyl Fischer carbene complexes (CO)(5)M=C(OEt)(CH=C(R(1)R(2)R(3)pz)Ph) (R(1)R(2)R(3)pz = pyrazolyl) 3 (M = Cr) and 4 (M = W), respectively, with an exclusive (E)-configuration in mild to excellent yields. The reaction of la and 3,5-dimethylpyrazole (2b) was monitored to demonstrate the formation and decomposition of complex 3b by H-1 NMR measurements in CDCl3 at 23degreesC. Complexes 3 and 4 were characterized with H-1, C-13{H-1} NMR, IR spectroscopies and elemental analysis. When the substituted pyrazoles were 3-methylpyrazole (2a) and 3,5-di-tert-butylpyrazole (2d), molecular structures of the corresponding (pyrazolyl)alkenyl Fischer carbene complexes 3a and 4d were characterized by X-ray crystallographic study. (C) 2004 Elsevier Ltd. All rights reserved.

Speciation of Rare-Earth Metal Complexes in Ionic Liquids: A Multiple-Technique Approach

The dissolution process of metal complexes in ionic liquids was investigated by a multiple-technique approach to reveal the solvate species of the metal in solution. The task-specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) is able to dissolve stoichiometric amounts of the oxides of the rare-earth elements. The crystal structures of the compounds [Eu-2(bet)(8)(H2O)(4)][Tf2N](6), [Eu-2(bet)(8)(H2O)(2)][Tf2N](6)center dot 2H(2)O, and [Y-2(bet)(6)(H2O)(4)][Tf2N](6) were found to consist of dimers. These rare-earth complexes are well soluble in the ionic liquids [Hbet][Tf2N] and [C(4)mim]- [Tf2N] (C(4)mim = 1-butyl-3-methylimidazolium). The speciation of the metal complexes after dissolution in these ionic liquids was investigated by luminescence spectroscopy, H-1, C-13, and Y-89 NMR spectroscopy, and by the synchrotron techniques EXAFS (extended X-ray absorption fine structure) and HEXS (high-energy X-ray scattering). The combination of these complementary analytical techniques reveals that the cationic dimers decompose into monomers after dissolution of the complexes in the ionic liquids. Deeper insight into the solution processes of metal compounds is desirable for applications of ionic liquids in the field of electrochemistry, catalysis, and materials chemistry.

Tracking the Fate of Microbially Sequestered Carbon Dioxide in Soil Organic Matter

The microbial contribution to soil organic matter (SOM) has recently been shown to be much larger than previously thought and thus its role in carbon sequestration may also be underestimated. In this study we employ C-13 ((CO2)-C-13) to assess the potential CO2 sequestration capacity of soil chemoautotrophic bacteria and combine nuclear magnetic resonance (NMR) with stable isotope probing (SIP), techniques that independently make use of the isotopic enrichment of soil microbial biomass. In this way molecular information generated from NMR is linked with identification of microbes responsible for carbon capture. A mathematical model is developed to determine real-time CO2 flux so that net sequestration can be calculated. Twenty-eight groups of bacteria showing close homologies with existing species were identified. Surprisingly, Ralstonia eutropha was the dominant group. Through NMR we observed the formation of lipids, carbohydrates, and proteins produced directly from CO2 utilized by microbial biomass. The component of SOM directly associated with CO2 capture was calculated at 2.86 mg C (89.21 mg kg(-1)) after 48 h. This approach can,differentiate between SOM derived through microbial uptake of CO2 and other SOM constituents and represents a first step in tracking the fate and dynamics of microbial biomass in soil.

Photocatalytic organic synthesis in an NMR tube:CC coupling of phenoxyacetic acid and acrylamide

NMR was used to study the semiconductor photocatalytic (SPC) CC coupling of phenoxyacetic acid (PAA) with acrylamide (ACM) in an NMR tube photoreactor. Using an NMR tube with a sol-gel titania inner coating as a photoreactor, this reaction is relatively clean, forming only 1 product, 4-phenoxybutanamide (4-PB), in yields up to 78%. This SPC reaction is used to assess the activity of the sol-gel titania coating as a function of their annealing temperature, which alters the surface area and phase of the titania, and the general reusability of the TiO coated NMR tubes. The optimum temperature range for annealing the sol-gel titania films is between 450 °C and 800 °C, with the maximum yield and rate attained at 450 °C. Despite a decrease in the initial rates of formation of 4-PB above an annealing temperature of 450 °C, the final product yields remained similar, giving maximum yields within 60 min of irradiation. The reusability study reveals that the activity of the sol-gel titania can quickly deteriorate with repeated use due to the adsorption of yellow/brown coloured, insoluble, most likely organic polymeric, material and its screening effect on the underlying photocatalyst. The titania can, however, be restored to its original activity by a simple heat treatment at 450 °C for 30 min.

Decomposition in soil and chemical characteristics of pollen

The input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo-ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C-to-N ratios and large water-soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16 degrees C an amount of C equivalent to 22-26% of the added pollen C was lost as CO2 within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water-soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid-state C-13 nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl- and methyl-C region (0-45 p.p.m.) indicative of aliphatic compounds, the O-alkyl-C (60-90 p.p.m.) and the acetal- and ketal-C region (90-110 p.p.m.) indicative of polysaccharides, and the carbonyl-C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N-alkyl-C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.

Decomposition in soil and chemical characteristics of pollen

The input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo-ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C-to-N ratios and large water-soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16 degrees C an amount of C equivalent to 22-26% of the added pollen C was lost as CO2 within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water-soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid-state C-13 nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl- and methyl-C region (0-45 p.p.m.) indicative of aliphatic compounds, the O-alkyl-C (60-90 p.p.m.) and the acetal- and ketal-C region (90-110 p.p.m.) indicative of polysaccharides, and the carbonyl-C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N-alkyl-C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.