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.     

Synthesis of well‐designed polymers carrying saccharide moieties via RAFT miniemulsion polymerization

Two hydrophobic vinyl saccharide monomers based on D ‐glucose and D ‐fructose were polymerized by employing the reversible addition‐fragmentation transfer (RAFT) miniemulsion polymerization technique to prepare well‐designed glycopolymers. Three dithiobenzoate‐RAFT agents [S?C(Ph)S? R], 1‐phenylethyl dithiobenzoate (PED), 2‐phenylprop‐2‐yl dithiobenzoate (PPD), and 2‐cyanoprop‐2‐yl dithiobenzoate (CPD), were used to control the growth of polymer chains. The best results were obtained in the presence of the PPD‐RAFT agent and the formed polymers have polydispersity index's (PDI) lower than 1.15. Under adequate miniemulsion polymerization conditions, a glycopolymer with PDI of 1.1 and molecular weight of 5 × 10⁴ g/mol has been successfully synthesized in a short reaction time of 100 min. Furthermore, some block copolymers containing saccharide segment with butyl or methyl methacrylate were prepared. Copyright © 2007 John Wiley & Sons, Ltd.     

呋喃西林水溶液在光和热作用下的稳定性

The influence of both light and heat on the stability of nitrofurazone aqueous solution was studied. Results show that in either heating experiments or the exposure to light at high temperatures, the degradation rate obeyed zero-order kinetics. The total rate constant ktotal caused by both light and heat can be divided into two parts: ktotal =kdark klight, where kdark and klight are the degradation rate constants caused by heat and light, respectively. The klight can be expressed as klight=Alight*exp(-Ea,light/RT)*E, where E is the illuminance of light, and Alight and Ea,light both are experimental constants. The values of these kinetic parameters were determined based on the experiments in the dark and upon exposure to three different light sources. Results show that the values of Alight and Ea, light varied with the light source. To save time, labor, and drugs, exponential heating experiments were employed and compared with the isothermal experiments. Results indicated that kinetic parameters obtained by exponential heating experiments are comparable to those obtained by isothermal experiments either in the dark or upon exposure to light.     

Two-stage Off-Gel isoelectric focusing: protein followed by peptide fractionation and application to proteome analysis of human plasma

This paper presents the recently introduced Off-Gel electrophoresis (OGE) technology as a versatile tool to reproducibly fractionate intact proteins and peptides into discrete liquid fractions. The coupling of two stages of OGE, i.e., the separation of intact proteins in a first-stage followed by fractionation of peptides derived from each protein fraction after proteolysis in a second stage, results in an array of 15 x 15 fractions that are directly amenable to additional peptide fractionation like reverse-phase liquid chromatography (RPC). The analysis of all second-stage peptide fractions from only the first-stage protein fraction representing pH 5.0 -5.15 by on-line reverse-phase LC-tandem mass spectrometry resulted in the identification of 53 proteins (337 peptides), of which 10 were on different immunoglobulin (Ig) chains, with an input of only 1.5 mg human blood plasma proteins. Increasing the protein load to approximately 12 mg increased the number of identified proteins in the same protein fraction to 73 proteins (449 peptides), of which 15 were Ig-related. Immunodepletion of six of the most abundant proteins (albumin, transferrin, haptoglobin, IgG, IgA, and alpha-1-antitrypsin) prior to first-stage OGE with an input of 1.5 mg of protein (equivalent to approximately 10 mg nondepleted plasma) resulted in the identification of 81 proteins (660 peptides), of which three were still Ig fragments. The pI-based separation of peptides appears to be nonuniform based on the theoretically determined pI values of identified peptides. This observation specifically accounts for the neutral zone (pI 5-8) and can be accounted for by the physicochemical properties of the peptides given by their amino acid composition. The power of OGE separation of proteins and peptides is discussed with a focus on the use of the knowledge about the pI of proteins and peptides that assist the validation of correct identifications together with the retention time of peptides on RPC.     

Theoretical study of the electronic spectrum of binuclear gold(I) complexes

The electronic structure and the spectroscopic properties of [Au₂(CS₃)₂]^?2, [Au₂(pym‐2‐S)₂] (pym = pyrimidethiolate), [Au₂(dpm)₂]⁺² (dpm = bis(diphosphino)methane) were studied using density functional theory (DFT) at the B3LYP level. The absorption spectrum of these binuclear gold(I) complexes was calculated by single excitation time‐dependent (TD) method. All complexes showed a ¹(5dσ* → 6pσ) transition associated with a metal–metal charge transfer, which is strongly interrelated with the gold–gold distance. Furthermore, we have calculated the frequency of the gold–gold vibration (ν_Au2) on the above complexes. The values obtained are theoretically in agreement with experimental range. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Synthesis,Characterization and Crystal Structures of new Coordination Polymers of Cerium(III) and Samarium(III) Containing 2,6‐Pyridinedicarboxylic Acid

The reaction of 2,6‐pyridinedicarboxylic acid ( 1 , LH₂) with CeCl₃·7H₂O and Sm(NO₃)₃·6H₂O in the presence of triethylamine led to the coordination polymer complexes [M(L)(LH)(H₂O)₂]·4H₂O [M = Ce ( 2 ) and Sm ( 3 )]. Both complexes were characterized by elemental analyses, IR spectroscopy and the crystal structures of 2 and 3 . Crystal data for 2 at ?80 °C: monoclinic, space group P2₁/c, a = 1404.6(1), b = 1122.1(1), c = 1296.1(1) pm, β = 102.09(1)°, Z = 4, R₁ = 0.0217 and for 3 at ?80 °C: monoclinic, space group P2₁/c, a = 1395.1(1), b = 1120.1(1), c = 1282.8(1) pm, β = 102.71(1)°, Z = 4, R₁ = 0.019.     

Zinc(II) and Cadmium(II) Complexes of the 3‐(2‐Pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PDPT) Ligand,Structural Studies of [Zn(PDPT)2Cl(ClO4)] and [Cd(PDPT)2(NO3)(ClO4)]

Two new mixed‐anion zinc(II) and cadmium(II) complexes of 3‐(2‐pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PDPT) ligand, [Zn(PDPT)₂Cl(ClO₄)] and [Cd(PDPT)₂(NO₃)(ClO₄)], have been synthesized and characterized by elemental analysis, IR‐ and ¹H NMR spectroscopy. The single crystal X‐ray analyses show that the coordination number in these complexes is six with four N‐donor atoms from two “PDPT” ligand and two of the anionic ligands, ZnN₄ClO_perchlorate, CdN₄O_nitrateO_perchlorate. Self‐assembly of these compounds in the solid state via π–π‐stacking interactions is discussed.     

Resolution of (+/-)-ibuprofen using (-)-brucine as a chiral selector by thin layer chromatography

The enantiomeric resolution of (+/-)-ibuprofen into its enantiomers was achieved by TLC on silica gel plate using optically pure (-)-brucine as a chiral selector and acetonitrile-methanol (5:1, v/v) as the solvent system. Spots were located in an iodine chamber. The detection limit was 4.9 microg. The effect of concentration of the chiral selector, temperature and pH on resolution has been studied.     

Enatiomeric analysis of simendan by CE with beta-CD as chiral selector compared with CMPA-HPLC

The chiral separation of simendan enantiomers using capillary electrophoresis was studied with beta-cyclodextrin (beta-CD) as chiral selector. The influences of the concentration and pH of borate buffer solution, beta-CD concentration and methanol content in the background electrolyte were investigated. These factors were compared with those in an HPLC with beta-CD as chiral mobile phase additive (CMPA-HPLC). The quantification properties of the developed CE method were examined. A baseline separation of simendan enantiomers was achieved in the background electrolyte of 20 mmol/L borate buffer (pH 11.0) containing 12 mmol/L beta-CD-methanol (50:50 in volume ratio). The CE method is comparable with CMPA-HPLC in chiral resolution, although the optimal pH in CE (11.0) is much higher than that (6.0) in CMPA-HPLC. This chiral CE method is applicable to the quantitative ananlysis and enantiomeric excess value determination of L-simendan.     

共振光散射成像检测5,10,15,20-四(对三甲基氨基苯)卟吩诱导的DNA超螺旋聚集体

A resonance light scattering （RLS） imaging method was proposed based on imaging and measuring the RLS features of single suprahelical species of DNA, and its appfication to DNA assay was also investigated. In acidic medium, porphine-5,10,15,20-tetrakis（p-phenyltlimethylaminium） （PTPTMA）, could stack along the molecular surface of DNA with the mode of long-range assembly to induce the formation of suprahelical species of DNA, resulting in strong RLS signals in the range of 450-510 nm. Under the excitation of 488 nm fight beam of argon ion laser source, single suprahelical species could be observed with the aid of a common microscope due to the strong scattered fight emitted by the suprahelical species. By capturing the RLS images of the single suprahelical species with a cooled charge coupled device （CCD） camera, and analyzing the RLS data, herein an RLS imaging method of DNA was proposed based on the linear relationship between the counts of suprahelical species in the detection focus plane and the concentration of DNA in nanograms. When 1.8 μmol/L PTPTMA was employed, both calf thymus DNA （ct DNA） and fish sperm DNA （fs DNA） in the range of 25-1100 ng/mL could be detected with the limits of detection lower than 25 ng/mL （3a）. Four synthetic samples were detected satisfactorily with relative standard deviations less than 5.1%.