CoCl_2·6H_2O or LaCl_3·7H_2O Catalyzed Biginelli Reaction. One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1 H)-ones

Ｉｎｔｒｏｄｕｃｔｉｏｎ1,4 Ｄｉｈｙｄｒｏｐｙｒｉｄｉｎｅｓｏｆｔｈｅｎｉｆｅｄｉｐｉｎｅｔｙｐｅ (ｅ .ｇ .Ｉ—ＩＩＩ)ａｒｅｔｈｅｍｏｓｔｓｔｕｄｉｅｄｃｌａｓｓｏｆｏｒｇａｎｉｃｃａｌｃｉｕｍｃｈａｎｎｅｌｍｅｄｉｃｉｎｅ ,ｗｈｉｃｈｈａｖｅｂｅｃｏｍｅａｌｍｏｓｔｉｎｄｉｓｐｅｎｓ ａｂｌｅｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｃａｒｄｉｏｖａｓｃｕｌａｒｄｉｓｅａｓｅｓｓｕｃｈａｓｈｙｐｅｒｔｅｎｓｉｏｎ ,ｃａｒｄｉａｃａｒｒｈｙｔｈｍｉａｓ ,ｏｒａｎｇｉｎａ .1Ｉｎｔｈｅｐａｓｔｄｅｃａｄｅ…     

Electrochemical behavior and determination of epinephrine at a mercaptoacetic acid self-assembled gold electrode

The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry. The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10⁻⁶ cm² s⁻¹. In 0.1 mol L⁻¹ phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the concentration of EP in the range of 1.0 × 10⁻⁵–2.0 × 10⁻⁴ mol L⁻¹ and 1.0 × 10⁻⁷–1.0 × 10⁻⁶ mol L⁻¹. The detection limit is 5 × 10⁻⁸ mol L⁻¹. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The method is simple, quick, sensitive and accurate.     

Enhanced and selective adsorption of mercury ions on chitosan beads grafted with polyacrylamide via surface-initiated atom transfer radical polymerization

Enhanced and selective removal of mercury ions was achieved with chitosan beads grafted with polyacrylamide (chitosan-g-polyacrylamide) via surface-initiated atom transfer radical polymerization (ATRP). The chitosan-g-polyacrylamide beads were found to have significantly greater adsorption capacities and faster adsorption kinetics for mercury ions than the chitosan beads. At pH 4 and with initial mercury concentrations of 10-200 mg/L, the chitosan-g-polyacrylamide beads can achieve a maximum adsorption capacity of up to 322.6 mg/g (in comparison with 181.8 mg/g for the chitosan beads) and displayed a short adsorption equilibrium time of less than 60 min (compared to more than 15 h for the chitosan beads). Coadsorption experiments with both mercury and lead ions showed that the chitosan-g-polyacrylamide beads had excellent selectivity in the adsorption of mercury ions over lead ions at pH < 6, in contrast to the chitosan beads, which did not show clear selectivity for either of the two metal species. Mechanism study suggested that the enhanced mercury adsorption was due to the many amide groups grafted onto the surfaces of the beads, and the selectivity in mercury adsorption can be attributed to the ability of mercury ions to form covalent bonds with the amide. It was found that adsorbed mercury ions on the chitosan-g-polyacrylamide beads can be effectively desorbed in a perchloric acid solution, and the regenerated beads can be reused almost without any loss of adsorption capacity.     

手性钛锆化合物在不对称合成中的应用

本文综述了近年来手性钛锆化合物在不对称合成中的应用, 特别是手性柄型金属钛和锆化合物在不对称合成中的应用。对这类催化剂的特点和前景作了简要介绍。     

样品价态对激光气化产生Cu/Cl团簇的组成和稳定性的影响

研究团控的形成条件、形成机理是目前团簇科学中的一个热点领域［‘］．产生气相团簇的方法主要有Knudsen高温炉扩散法、粒子溅射法、激光气化／分子束法、直接激光气化法·因为不需要另加缓冲气体，直接激光气化法【刀具有对体系真空要求较低，装置简单，容易和飞行时间质谱结     

Synthesis and characterization of functional l-lactic acid/citric acid oligomer

Oligomers of l-lactic acid and citric acid (PLCA) were synthesized by reacting lactic acid with citric acid in the presence of stannous chloride. The chemical compositions of these multicarboxylated oligomers were verified by FT-IR and ¹H-NMR spectroscopy. The thermal characteristics of the oligomers, such as glass transition temperature T_g, melting temperature T_m and melting enthalpy, were confirmed by DSC. The crystallinity of the oligomers were determined by DSC and WXRD. Meanwhile, the acid-base surface characteristics of PLCA have been determined by contact angle. The results implicated that these oligomers may be used to entrap the cospecies on PLLA surface in tissue engineering.     

Determination of levodopa by capillary electrophoresis with chemiluminescence detection

A rapid and simple method using capillary electrophoresis (CE) with chemiluminescence (CL) detection was developed for the determination of levodopa. This method was based on enhance effect of levodopa on the CL reaction between luminol and potassium hexacyanoferrate(III) (K₃[Fe(CN)₆]) in alkaline aqueous solution. CL detection employed a lab-built reaction flow cell and a photon counter. The optimized conditions for the CL detection were 1.0 × 10⁻⁵ M luminol added to the CE running buffer and 5.0 × 10⁻⁵ M K₃[Fe(CN)₆] in 0.6 M NaOH solution introduced postcolumn. Under the optimal conditions, a linear range from 5.0 × 10⁻⁸ to 2.5 × 10⁻⁶ M (r = 9991), and a detection limit of 2.0 × 10⁻⁸ M (signal/noise = 3) for levodopa were achieved. The precision (R.S.D.) on peak area (at 5.0 × 10⁻⁷ M of levodopa, n = 11) was 4.1%. The applicability of the method for the analysis of pharmaceutical and human plasma samples was examined.     

Fluorescence resonance energy transfer in doubly-quantum dot labeled IgG system

The mouse immunoglobulin G (mouse IgG) as a kind of bio-molecule was labeled with two different luminescent colloidal semiconductor quantum dots (QDs), green-emitting CdTe quantum dots and red-emitting CdTe quantum dots in this work. As a result of the fluorescence resonance energy transfer (FRET) between the two different sizes nanoparticles with mouse IgG as the binding bridge, a significant enhancement of the emission of the red-emitting CdTe quantum dots and the corresponding quenching of the emission of green-emitting CdTe quantum dots were observed. The relationship between the concentration of the mouse immunoglobulin G and the fluorescence intensity ratio (I_a/I_d) of acceptors and donors was studied also. Under optimal conditions, the calibration graph is linear over the range of 0.1–20.0 mg/L mouse IgG.     

Investigation of the interaction between acridine orange and bovine serum albumin

The results from the measurement of the fluorescence spectrum showing the binding characteristics of acridine orange (AO) and bovine serum albumin (BSA) are reported. It was found that the equilibrium constant k=4848.64 l mol⁻¹, and the number of binding sites n=0.82. Based on the mechanism of the Forster energy transference, the transfer efficiency of energy and distance between the acceptor AO and BSA were found. The interaction between AO and BSA have been verified as consistent with the static quenching procedure and the quenching mechanism is related to the energy transfer.     

A MORPHOLOGICAL STUDY OF POLY（DIVINYLBENZENE-co-ACRYLIC ACID） IN CROSSLINKING PRECIPITATION POLYMERIZATION

Divinylbenzene-80 （DVB-80） and polar monomer acrylic acid （AA） having hydrogen bonding at a total monomer loading of 5 vol% were precipitated-copolymerized in a variety of organic solvents with 2,2＇-azobis（isobutyronitrile） （AIBN） as initiator. The experiments were investigated from a two-dimensional matrix, i.e., the actual crosslinking degree of DVB varying from 0 to 80% and the solvent composition varying from 0 to 100% of toluene mixture with acetonitrile, when the mixture of acetonitrile and toluene was used as the reaction solvent. Under various reaction conditions, six distinct morphologies including soluble polymers, swellable microgels, coagulum, irregular microparticles, and nano-/micrometer microspheres were formed and the structures of these polymer architectures were described. A morphological map was utilized to discuss the effects of both crosslinking degree of DVB and composition of solvent on the transitions between morphology domains. The results demonstrated that the microspheres are formed by an internal contraction due to the marginal solvency of the continuous phase and the crosslinking of the polymer network through the covalent bonding from DVB as well as the interchain hydrogen-bonding between the carboxylic acid units.