Cellulose hydrolysis using zinc chloride as a solvent and catalyst

Cellulose gel with < 10% of crystallinity was prepared by treatment of microcrystalline cellulose, Avicel, with zinc chloride solution at a ratio of zinc chloride to cellulose from 1.5 to 18 (w/w). The presence of zinc ions in the cellulose gels enhanced the rate of hydrolysis and glucose yield. The evidence obtained from X-ray diffraction, iodine absorption experiments; and Nuclear Magnetic Resonance spectra analysis suggested the presence of zinc-cellulose complex after Avicel was treated with zinc chloride. Zinc-cellulose complex was more susceptible to hydrolysis than amorphous cellulose. Under the experimental condition, cellulose gels with zinc ions were hyrolyzed to glucose with 95% theoretical yield and a concentration of 14% (w/v) by cellulases within 20 h. The same gel was hydrolyzed by acid to glucose with 91.5% yield and a concentration of 13.4% (w/v).     

Oxidative Methyl Esterification of Primary Alcohols with Iodine‐Mediated Poly[4‐(Diacetoxyiodo)Styrene]

An operationally simple oxidative methyl esterification of primary alcohols in good yields using an iodine‐mediated poly[4‐(diacetoxyiodo)styrene] in methanol at room temperature is described. The polymeric reagent can be regenerated and reused as an environmentally benign reagent.     

A General, Highly Efficient Ullmann C-O Coupling Reaction under Microwave Irradiation and the Effects of Water

A general, rapid and highly efficient method for the synthesis of diaryl ethers under the assistance of microwave irradiation was described. A series of diaryl ethers were prepared by direct coupling of phenols and aryl halides in good to excellent yields in anhydrous DMF or NMP at 150 ℃ within 20 rain. The presence of water was found to have a significant impact on the Ullmann C-O coupling reaction between aryl halides and phenols under microwave irradiation.     

Determination of Osmium(VIII) by Flow Injection-Kinetic Methods Using Bromopyrogallol Red and Hydrogen Peroxide

A new flow injection-kinetic method has been developed for the determination of trace amount of osmium(WI), based on its catalytic effect on the bromopyrogallol red and hydrogen peroxide reaction. The reaction is followed spectrophotometrically by measuring the decrease in absorbance at 559 nm. The calibration graph for osmium(VIII) is linear over the range from 0.0040 to 0.10 μg/ml and the detection limit and sampling frequency are 0.0030 μg/ml and 47 per hour, respectively. The proposed method was applied to the determination of trace amounts of osmium in refined ores and chlorination residues with satisfactory results.     

A fluorescence spectroscopic study of the interaction between epristeride and bovin serum albumine and its analytical application

A new spectrofluorimetric method to determine epristeride (EP) has been developed, which based on the EP has a strong ability to quench the intrinsic fluorescence of bovine serum albumin (BSA). There was the relationship between the fluorescence quenching intensity of BSA (ΔF = F_BSA − F_BSA-EP) and the concentration EP. The quenching mechanism was investigated with the quenching type, the association constants, the number of binding sites and basic thermodynamic parameters. The method had been successfully applied to the analysis of EP in real samples and the obtained results were in good agreement with the results of official method-HPLC.     

New diorganotin(IV) derivatives of 7-hydroxycoumarin (umbelliferone) and their adducts with 1,10-phenanthroline

New diorganotin(IV) derivatives of the general formula R2Sn(Umb)2 (where R = n-Bu, n-Oct and Ph; Umb = umbelliferone anion) have been synthesized either by the reaction of R2SnO with umbelliferone under azeotropic removal of water or by the reaction of R2SnCl2 with sodium salt of umbelliferone. Further, the adducts of the general formula R2Sn(Umb)2.phen (where R = n-Bu and n-Oct; phen = 1,10-phenanthroline) have also been synthesized by the interaction of R2Sn(Umb)2 with 1,10-phenanthroline. The bonding and coordination behavior in these derivatives are discussed on the basis of IR and 119Sn M?ssbauer spectroscopic studies in solid state. Their coordination behavior in solution is discussed by the multinuclear (1H, 13C and 119Sn) NMR spectral studies. The M?ssbauer and IR studies indicate that umbelliferone acts as a monoanionic bidentate ligand in R2Sn(Umb)2 coordinating through O(7) and O(1). A distorted octahedral geometry around tin has been proposed for R2Sn(Umb)2 as well as for R2Sn(Umb)2.phen in solid state. The newly synthesized derivatives have been tested for their anti-inflammatory and cardiovascular activities. The average LD50 value >1000 mg kg(-1) of these compounds indicates their safety margin.     

Chains, ladders and sheets of d metal–organic polymers generated from the flexible bipyridyl ligands

By use of the three-layer diffusion method, reactions of flexible bipyridyl ligands (4,4′-bpp or 3,3′-bpp) with M(II) salts (M = Zn, Cd) and multi-carboxylate ligands resulted in the formation of four interesting d¹⁰ metal–organic coordination polymers: [Zn(μ-4,4′-bpp)Br₂]_n (1), [Zn(μ-4,4′-bpp)(1,2-bdc)]_n · nH₂O (2), [Zn(μ-3,3′-bpp)(1,3-bdc)]_n · nCH₃OH · 2nH₂O (3) and [Cd(μ-3,3′-bpp)(C₄H₂O₄)]_n · 3nH₂O (4) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 3,3′-bpp = 2,2 ′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene; bdc=benzenedicarboxylate, C₄H₄O₄ = fumaric acid). Complex 1 has a 2D sheet structure consisting of two unusual zigzag Zn(II) chains which are nearly perpendicular to each other. Complex 2 is comprised of two-leg ladders, in which [Zn(4,4′-bpp)] chains serve as the side rails and 1,2-bdc ligands serve as the cross rungs. In complex 3, every two 1,3-bdc ligands connect the neighbouring Zn(II)-3,3′-bpp dimetallic rings in η¹ coordination modes into an interesting chain structure. Complex 4 consists of an anionic macrocycle-containing cadmium dicarboxylate sheets that are separated by 3,3′-bpp. These d¹⁰ metal complexes exhibit high thermal stabilities and strong luminescence efficiencies.     

聚苯乙烯磺酸掺杂聚苯胺的合成

以苯胺（An）为单体，过硫酸铵（APS）为氧化剂，在聚苯乙烯磺酸（PSSA）的水溶液中，合成了可完全溶于水的PSSA掺杂PAn。研究了An浓度，PSSA浓度，APS浓度，APS的滴加时间，反应时间及温度对An聚合反应及其产物的水溶性，导电性及特性粘度[η]的影响。结果表明：在比较宽的实验条件下，都可以合成出具有良好导电性的可溶于水的PSSA掺杂PAn；其中当An：PSSA:APS的摩尔比为1．7：2．5：1，APS溶液的滴加时间为3h，反应时间为1h，反应温度为14℃时，得到的掺杂PAn导电率最高达0．156S／cm。     

Self-assembly of amphiphilic hexapyridinium cations at the air/water interface and on HOPG surfaces.

Mono- and multilayers of a novel amphiphilic hexapyridinium cation with six eicosyl chains (3) are spread at the air/water interface as well as on highly ordered pyrolytic graphite (HOPG). On water, the monolayer of 3 is investigated by recording surface pressure/area and surface potential/area isotherms, and by Brewster angle microscopy (BAM). Self-organized tubular micelles with an internal edge-on orientation of molecules form at the air/water interface at low surface pressure whereas multilayers are present at high surface pressure, after a phase transition. Packing motifs suggesting a tubular arrangement of the constituting molecules were gleaned from atomic force microscopy (AFM) investigations of Langmuir-Blodgett (LB) monolayers being transferred on HOPG at different surface pressures. These LB film structures are compared to the self-assembled monolayer (SAM) of 3 formed via adsorption from a supersaturated solution, which is studied by scanning tunnelling microscopy (STM). On HOPG the SAM of 3 consists of nanorods with a highly ordered edge-on packing of the aromatic rings and an arrangement of alkyl chains which resembles the packing of molecules at the air/water interface at low surface pressure. Additional details of the molecular packing were gleaned from single-crystal X-ray structure analysis of the hexapyridinium model compound 2b, which possesses methyl instead of eicosyl residues.     

有机官能化MSU-x孔分子筛的界面特征

MSU- x是自 M41S系列介孔分子筛问世以来所合成的另一类新型介孔分子筛材料 ,它具有三维立体交叉排列的 " worm- like"孔道结构特征及采用中性模板剂、廉价无毒等诸多合成优点 [1～ 4],有着潜在的应用价值 .为了改善纯硅的介孔材料的表面和孔道性质 ,扩大其应用领域 ,除了在骨架引入金属离子或在其孔道中负载催化活性物质外 ,对介孔材料进行有机官能化制备无机-有机杂化材料改善其骨架和孔道性质是当前研究的热点之一 [5].正是由于活性有机基团的存在 ,使得这些材料可直接用于催化反应 ,或作为中间介质成为其它络合离子的主体 .由于有机基…