A novel and selective oxidation of benzylic alcohols with polymer-supported periodic acid under mild aprotic conditions

A new polymeric oxidizing reagent was prepared by supporting periodic acid on poly（1,4-phenylene-2,5-pyridine dicarboxyamide）. This polymeric reagent was used for the selective oxidation of primary benzylic alcohols to the corresponding benzaldehydes in CH₃CN at reflux conditions.Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions.Allylic alcohols were also converted to the corresponding aldehydes with good yields.     

Preconcentration and analysis of gold from cyanide solutions with the use of a microcolumn packed with the phosphine oxide Cyanex 921

The phosphine oxide Cyanex 921 (tri-n-octylphosphine oxide) was found to be a very efficient extradant for gold from aurocyanide aqueous solutions. A system comprising a microcolumn packed with this new reagent was developed for the separation and enrichment of gold. Because of the high selectivity of the developed system it is possible to analyze gold in the presence of an excess of other metals and/or in high ionic strengh solutions.     

Polymer‐Supported Thiocyanate as New,Versatile and Efficient Polymeric Reagent for Conversion of Alkyl Halides to Corresponding Alkyl Thiocyanates under Mild Conditions

Crosslinked poly(N‐methyl‐4‐vinylpyridinium)thiocyanate [P₄‐Me]SCN (II) is prepared easily and is used as a new polymeric reagent for synthesis of alkyl thiocyanates from alkyl halides under mild and nonaqueous conditions. The used polymeric reagent usually can be removing quantitatively and be regenerated.     

Combined use of platinum(II) complexes and palladium(II) complexes for selective cleavage of peptides and proteins

This study shows, for the first time, the advantages of combining two transition-metal complexes as selective proteolytic reagents. In this procedure, cis-[Pt(en)(H(2)O)(2)](2+) is followed by [Pd(H(2)O)(4)](2+). In the peptide AcAla-Lys-Tyr-Gly-Gly-Met-Ala-Ala-Arg-Ala, the Pt(II) reagent cleaves the Met6-Ala7 peptide bond, whereas the Pd(II) reagent cleaves the Gly4-Gly5 bond. In the peptide AcVal-Lys-Gly-Gly-His-Ala-Lys-Tyr-Gly-Gly-Met-Ala-Ala-Arg-Ala, the Pt(II) reagent cleaves the Met11-Ala12 peptide bond, whereas the Pd(II) reagent cleaves the Gly3-Gly4 bond. All cleavage reactions are regioselective and complete at pH 2.0 and 60 degrees C. Each metal ion binds to an anchoring side chain and then, as a Lewis acid, activates a proximal peptide bond toward hydrolysis by the solvent water. The selectivity in cleavage is a consequence of the selectivity in this initial anchoring. Both Pt(II) and Pd(II) reagents bind to the methionine side chain, whereas only the Pd(II) reagent binds to the histidine side chain under the reaction conditions. Consequently, only methionine residues direct the cleavage by the Pt(II) reagent, whereas both methionine and histidine residues direct the cleavage by the Pd(II) reagent. The Pt(II) reagent cleaves the first bond downstream from the anchor, i.e., the Met-Z bond. The Pd(II) reagent cleaves the second bond upstream from the anchor, i.e., the X-Y bond in the X-Y-Met-Z and in the X-Y-His-Z segments. The diethylenetriamine complex [Pt(dien)(H(2)O)](2+) cannot promote cleavage. Its prior binding to the Met11 residue in the second peptide prevents the Pd(II) reagents from binding to Met11 and cleaving the Gly9-Gly10 bond and directs the cleavage by the Pd(II) reagent exclusively at the Gly3-Gly4 bond. Our new method was tested on equine myoglobin, which contains 2 methionine residues and 11 histidine residues. The complete methionine-directed cleavage of the Met55-Lys56 and Met131-Thr132 bonds by the Pt(II) reagent produced three fragments, suitable for various biochemical applications because they are relatively long and contain amino and carboxylic terminal groups. The deliberately incomplete histidine-directed cleavage of the long fragments 1.55 and 56.131 at many sites by the Pd(II) reagent produced numerous short fragments, suitable for protein identification by mass spectrometry. The ability of combined Pt(II) and Pd(II) complexes to cleave proteins with explicable and adjustable selectivity and with good yields bodes well for their greater use in biochemical and bioanalytical practice.     

镉的高灵敏显色体系研究及表面活性剂作用机理

本文以2-氯-4-硝基苯重氮氨基偶氮苯(CNDAA)为显色剂, 研究了镉的高灵敏显色体系及表面活性剂的作用机理。研究结果表明: 对于Cd(II)-CNDAA配合物, 非离子型、阴离子型及阴-非混合型表面活性剂对此有显著的增溶增敏作用, 并以Cd(II)-CNDAA-SF显色体系建立了光度法测定微量镉的高灵敏新方法, 并对几种测定方法进行了比较, 筛选出显色条件宽容、选择性好的体系。该体系用于铝合金样品中镉的测定, 结果满意。另外, 还提出了Cd(II)-CNDAA配合物的结构, 对表面活生剂对体系的作用作了描述, 并阐明了试剂的酸性离解常数(pK~a)与显色酸度以及方法的选择性三者之间的关系。     

Design of Schiff base complexes of Co(II) for the preparation of iodide-selective polymeric membrane electrodes

The response characteristics of some iodide-selective solvent polymeric membrane electrodes based on with N,N'-bis(salicylaldehyde-n-octyl) diimine cobalt(II) (Co(II)SAODI) which is a more lipophilic substitute for a previously reported iodide-carrier are described. The electrode doped with Co(II)SAODI into a plasticized poly(vinyl chloride) membrane exhibits an anti-Hofmeister selectivity pattern with high selectivity toward iodide, long lifetime and small interference from H(+). Quartz crystal microgravimetric measurements and ac impedance experiments show that the excellent selectivity for iodide is related to the unique interaction between the carriers and iodide and steric effect associated with the structure of the Schiff base ligands.     

Biacetyl monoxime glycinimine as a selective reagent for palladium and nickel

Biacetyl monoxime glycinimine is proposed as a new reagent for the selective gravimetric and extractive photometric determination of Pd(II) and Ni(II). The reagent forms yellow and rose-red water-insoluble complexes with Pd (pH 0.5–5.5) and Ni (pH 5.0–11.2) respectively. The complexes can be used for direct gravimetric determination or extracted with molten naphthalene. The solidified naphthalene—complex mixture is dissolved in chloroform and measured photometrically. The effects of experimental variables and diverse ions are reported. The proposed reagent offers better selectivity than dimethylglyoxime.     

Simultaneous Detection of Copper,Lead and Zinc on Tin Film/Gold Nanoparticles/Gold Microelectrode by Square Wave Stripping Voltammetry

In this work, three heavy metals (Cu(II), Pb(II) and Zn(II)) in wide potential window were simultaneously detected on tin film/gold nanoparticles/gold microelectrode (Sn/GNPs/gold microelectrode) by the method of square wave stripping voltammetry. The Sn/GNPs/gold microelectrode was fabricated by in situ plating of a Sn film on a gold nanoparticles (GNPs) modified gold microelectrode. The influence of hydrogen overflow on stripping of Zn(II) on the gold microelectrode was reduced by modification of GNPs, which made the stripping potential of target metals shift positively. The interference of sulfhydryl groups was reduced and the selectivity of the microelectrode was improved due to the addition of Sn in the detection solution. After accumulation at ?1.4 V for 300 s in acetate buffer solution (0.1 mol L^?1, pH 4.5), the Sn/GNPs/gold microelectrode revealed a good linear behavior in the examined concentration ranges from 5 to 500 µg L^?1 for Cu(II) and Pb(II), and from 10 to 500 µg L^?1 for Zn(II), with a limit of detection of 2 µg L^?1 for Cu(II), 3 µg L^?1 for Pb(II) and 5 µg L^?1 for Zn(II) (S/N=3). When compared with a Sb/GNPs/gold microelectrode and a Bi/GNPs/gold microelectrode, the Sn/GNPs/gold microelectrode showed the best stripping performance to Cu(II), Pb(II) and Zn(II). As a new type of environment‐friendly electrode, the Sn/GNPs/gold microelectrode has potential applications for detection of heavy metals.     

Some synthesized polymeric composite resins for the removal of Co(II) and Eu(III) from aqueous solutions

Summary The ion-exchange and sorption characteristics of new polymeric composite resins, prepared by gamma radiation were experimentally studied. The composite resins show high uptake for Co(II) and Eu(III) ions in aqueous solutions in a wide range of pH. The selectivity of the resins for Co(II) or Eu(III) species in presence of some competing ions and complexing agents (as Na⁺, Fe³⁺, EDTANa₂, etc.) was compared. Various factors that could affect the sorption behavior of metal ions (Co(II) and Eu(III)) on the prepared polymeric composite resins were studied such as ionic strength, contact time, volume mass ratio.     

The Active Transport of Ions of Rare-Earth Elements,Alkali Metals,Al(III), and Mg(II) with New Lipophilic N,N-Bis[(Dihexylphosphoryl)Methyl]Octylamine

Abstract

The Active Transport of Ions of Rare-Earth Elements, Alkali Metals, Al(III) and Mg(II) with N,N- Bis[(dihexylphosphoryl)methyl]octylamine was studied. It is found that with the selected reagent the flow of ions S?(III) and Nd(III) is several times higher than the flow of ions Al(III) and Mg(II). Also, the mixtures of bis(aminophosphoryl) reagent and mono-/dithiophosphoric acids show evidence for synergistic effects with high selectivity when used for the extraction of Li(I).     

Determination of Nanomolar Levels of Mercury(II) by Exploiting the Silver Stain Enhancement of the Aggregation of Aptamer-Functionalized Gold Nanoparticles

An ultrasensitive method for the determination of mercury(II) ions was developed based on mercury(II)-induced strong and selective binding of thymine-thymine mismatches between aptamers on gold nanoparticles and a signal amplification effect caused by a silver stain. The gold nanoparticles were first coated with a single-stranded DNA aptamer rich in thymine. In the presence of mercury(II), the functionalized gold nanoparticles aggregated due to the formation of thymine-Hg(II)-thymine complexes resulting in a largely reduced surface area of the gold nanoparticles when exposed to silver ions during staining. Therefore, fewer silver ions were reduced, and the average grey values, as measured by a scanner, were lower. The average grey values were linearly related to the logarithm of mercury(II) concentration from 1 to 500 nM. In addition, there were no significant interferences by common metal ions due to the high specificity of the interaction between mercury(II) and the aptamer. The method offers high sensitivity, good selectivity, and the absence of large equipment that makes it suitable for field analysis.     

Analytical Separation of Copper(II), Cobalt(II) and Nickel(II) Using Polymer Bound Anthrantic Acid

Abstract

The preferential complexing tendency of different nietal ions towards chelating agents anchored on a polymer has been used for separation of transition metals. the anthranilic acid group was anchored on the polymeric cellulose back-bone by successive coupling with trifunctional reagent cyanuric chloride, in diozane medium, at pH 7 and 9–10, respectively. This polymer bound chelating agent was used to separate copper(II), nickel(II) and cobalt(II) in the concentration range 1.0–0.1 mmol/L. the separation of a mixture of two components was quantitative using column chromatography.     

Modified Xerogel-Based Indicator Powders for Determining Ascorbic Acid and Hydrazines by Solid-Phase Spectrophotometry and Visual Tests

The effect of Cu(II), Ti(IV), Bi(III), and Fe(III) on the reduction of the Vavele reagent (a mixture of series 12 and 18 phosphomolybdic acids) with ascorbic acids and hydrazines was studied. It was found that, in the presence of copper(II), the Vavele reagent both nonimmobilized and immobilized on silicic acid xerogel is reduced in 10–15 min. Procedures were developed for determining ascorbic acid and hydrazines by solid-phase spectrophotometry and in visual tests using silicic acid xerogel modified with the Vavele reagent and copper(II) as an indicator powder. The precision, accuracy, and selectivity of the developed procedures were estimated. The results of determining ascorbic acids in dry fruit drinks were presented. The procedure proposed for the test determination of hydrazines in process solutions was certified by the State Committee for Standards and Metrology of Russian federation and recorded in the register of test systems under the number TS 7-99.     

Voltammetric Detection of Oxidative DNA Damage Based on Interactions between Polymeric Dyes and DNA

Oxidative damage of DNA was assessed with glassy carbon electrode (GCE) coated with electropolymerized Methylene Blue (MB). For this purpose, DNA solution was first mixed with an oxidant (Fenton reagent, H₂O₂ alone and in the presence of Cu(II) ions) and then placed on the polymeric film surface. After washing, the cyclic voltammogram was recorded in buffer solution and the anodic peak potential measured against that before the contact with DNA. Oxidative DNA damage resulted in remarkable decrease of the anodic peak potential which depended on the oxidant nature and incubation period. Specificity of the DNA – MB interactions was confirmed by surface plasmon resonance (SPR) measurements. Similar experiment performed with polymerized Methylene Green (MG) and Neutral Red (NR) showed lower selectivity of the response toward various sources of reactive oxygen species. The protocol of the DNA damage detection was tested on the estimation of antioxidant properties of green tea extract and red table wine.     

Gold‐Catalyzed Cascade Reactions for Synthesis of Carbo‐ and Heterocycles: Selectivity and Diversity

This account describes our recent efforts devoted to gold chemistry since 2009. Based on furyl–Au 1,3‐dipole analogues and related gold carbene intermediates, a rich variety of gold‐catalyzed cascade reactions have been developed, which provide facile access to a diverse range of novel carbo‐ and heterocycles. In these reactions, the selectivity can be well controlled by the catalyst (ligand and metal), substrate or reagent. In addition, we have also developed the corresponding enantioselective variants, which are guided by bis(phosphinegold) complexes derived from axially chiral scaffolds and asymmetric gold/chiral Brønsted acid relay catalysis.     

Disodium-1,8-dihydroxy-naphthalene-3,6-disulphonate (chromotropic salt) as a reagent in inorganic analysis

Summary The compound disodium-1,8-dihydroxy-naphthalene-3,6-disulphonate (sodium salt of chromotropic acid) is employed as a colorimetric reagent for titanium. It is also known to produce coloured complexes with chromium(VI), vanadium and uranium. In the present paper the formation of colour with forty metallic ions has been studied qualitatively, in neutral as well as in alkaline and acidic media. It has been found that the reagent yields coloured complexes with mercury(I), tin(IV), platinum(IV), gold(III), tellurium(VI), molybdenum(VI), iron(III), aluminium(III), chromium(III), and uranyl(II) besides those recorded above.The colour reactions are particularly sensitive to uranyl(II), iron(III), mercury(I), tin(IV), gold(III) und molybdenum(VI).     

Symposium on Biomedical Polymers

ABSTRACT

Glycine functions were incorporated into 2–20 mol% N,N′-methylene-bis-acrylamide (NNMBA)-crosslinked polyacrylamides by transamidation with excess sodium salt of glycine. Complexation characteristics of glycine functions in different structural environments were investigated towards Co(II), Ni(II), Cu(II) and Zn(II) ions. The observed trend in complexation was found to be: Cu(II) > Ni(II) > Co(II) > Zn(II). The polymeric ligands and metal complexes were characterized by various spectral techniques. The polymeric ligands could be recycled several times and the metal ion desorbed resins showed specificity to the desorbed metal ion than other metal ions. This originates from the development of certain ‘pockets’ left by the desorbed metal ion or the ‘memory’ of the polymeric ligands for the desorbed metal ion. This lightly crosslinked systems showed much faster rebinding kinetics. The conditions of metal ion binding and rebinding were optimized to exploit the specific and selective separation of metal ions using metal ion desorbed systems. The specificity and selectivity characteristics depend on the degree of NNMBA crosslinking.     

Polysiloxane-bound ligand accelerated catalysis: a modular approach to heterogeneous and homogeneous macromolecular asymmetric dihydroxylation ligands

Polysiloxane acts as a modular scaffold for macromolecular reagent development. Two separate components were covalently integrated into one material, one constituent provided reagent functionality, the other modulated solubility. In particular cinchona alkaloid based ligands used in the osmium tetroxide catalyzed asymmetric dihydroxylation (AD) reaction were covalently attached to commercially available polysiloxane. To enhance the reactivity of these polymeric ligands, multifunctional reagents were designed to include both the cinchona alkaloid and an alkoxyethylester solubilizing moiety providing random co-polymers. While the mono-functional materials led to heterogeneous conditions, the bi-functional polymers resulted in homogeneous reaction mixtures. Although both reagent types provided diol products with excellent yield and selectivity (>99% ee in nearly quantitative yield) the homogeneous analog has nearly twice the reactivity. Every repeat unit in the heterogeneous material was functionalized along the polysiloxane backbone while approximately half of these sites contained ligand in the homogeneous version. This approach led to macromolecular catalysts with high loadings of ligand and therefore materials with very low equivalent weights. Although these polymers are highly loaded they do maintain reactivity on a par with their free ligand counterpart. Using straightforward purification techniques (i.e. precipitation, simple filtration, or ultrafiltration) these polymeric ligands were easily separated from diol product and reused multiple times. Polysiloxane is a viable support for the catalysis of AD reactions and may provide a generally useful backbone for other catalytic systems.     

Studies on coordination polymers : Part II. Coordination polymers of 1,6-dihydroxyphenazine

Coordination polymers of 1, 6-dihydroxyphenazine (I) with Cu(II), Zn(II), Ni (II), Co(II) and Hg(II) were prepared and studied. All the polymers formed were dark blue to black powders, very insoluble in the common solvents, apparently of low molecular weight, and decomposed at temperatures ranging from 200 to 280°. The zinc polymer was the most stable, mercury the least. Infrared studies confirmed the proposed chelation reaction between the metal ion and (I). The polymers of Co and Hg were amorphous, whereas those of Cu, Zn, and Ni were crystalline. When used as a spot test reagent, (I) gave instant color reactions with 15 common ions but neither the sensitivity nor selectivity of the reagent is impressive.     

后交联胺化聚苯乙烯树脂对铜离子的吸附选择性研究

以三乙烯四胺化交联聚苯乙烯(PS-NH2)为原料,以环氧氯丙烷(ECH)为交联剂,合成了后交联胺化聚苯乙烯树脂Ps-NH2-ECH.研究了PS-NH2和PS-NH2-ECH在静态条件下对重金属离子Cu2 、Ni2 、Zn2 、Cd2 、Pb2 的吸附选择性,以及PS-NH2-ECH在动态条件下对Cu2 、Ni2 的吸附选择性.结果表明,PS-NH2-ECH对Cu2 的吸附选择性较Ps-NH2有显著提高.