Electrochemical studies on the interaction of heparin with crystal violet and its analytical application

In this paper, crystal violet (CV) was used to determine heparin concentration by linear sweep voltammetry on a dropping mercury electrode (DME). In Britton-Robinson (B-R) buffer solution, pH 3.0, CV had a well-defined second-order derivative linear sweep voltammetric reductive wave at −0.74 V (vs. SCE). After the addition of heparin to the CV solution, the reductive peak current decreased greatly with the positive movement of the peak potential and without appearance of new peaks in the scanning potential range. Based on the decrease in the reductive peak current, a new voltammetric method for the determination of heparin was established. The conditions for the interaction and the electrochemical detection were optimized, and interfering substances were investigated. Under the optimal conditions, the decrease in reductive peak currents of CV was proportional to heparin concentration in the range 0.1–8.0 mg/L with the linear regression equation Δip″(nA) = 400.42 + 1563.11c (mg/L), (n = 14, γ = 0.993). The detection limit was 0.092 mg/L. This new method was further successfully applied to the determination of heparin content in heparin sodium injection samples with satisfactory results. The binding ratio and binding mechanism were also studied by the electrochemical method. The text was submitted by the authors in English.     

Pt微粒修饰纳米纤维聚苯胺电极对甲醇氧化电催化

以脉冲电流法制备的纳米纤维状聚苯胺(PANI)为Pt催化剂载体，用它制备了甲醇阳极氧化的催化电极Pt/（nano-fibular PANI）.研究结果表明, Pt/（nano-fibular PANI）电极对甲醇氧化具有很好的电催化活性,并有协同催化作用.在相同的Pt载量条件下， Pt/（nano-fibular PANI）电极比Pt微粒修饰的颗粒状聚苯胺电极Pt/(granular PANI)具有更好的电催化活性.此外， Pt的电沉积修饰方法同样影响Pt/（nano-fibular PANI）电极对甲醇氧化的催化活性.脉冲电流法沉积Pt形成的复合电极较循环伏安法电沉积得到的Pt复合电极具有更优异的催化活性.     

SYNTHESIS OF DERIVATIVES OF 3-β-D-XYLOPYRANOSYL-1,2,4-OXADIAZOLES

The synthesis of derivatives of 3-β-D-xylopyranosyl-1,2,4-oxadiazolesis accomplished by condensing protected β-D-xylopyranosyl amidoxime with acidanhydrides or various substituted benzoyl chlorides in good yield.Thestructures of now derivatives were identified by spectra and elemental analysis.The stability of 1,2,4-oxadiazole ring and mechanism of cyclization were.investigated.     

Theoretical studies on the smallest fullerene: from monomer to oligomers and solid States

Hybrid B3LYP and density-functional-based tight-binding (DFTB) computations on the solid-state structures and electronic properties of the C(20) fullerene monomer and oligomers are reported. C(20) cages with C(2), C(2h), C(i), D(3d), and D(2h) symmetries have similar energies and geometries. Release of the very high C(20) strain is, in theory, responsible for the ready oligomerization and the formation of different solid phases. Open [2+2] bonding is preferred both in the oligomers and in the infinite one-dimensional solids; the latter may exhibit metallic character. Two types of three-dimensional solids, the open [2+2] simple cubic and the body-centered cubic (bcc) forms, are proposed. The energy of the latter is lower due to the better oligomer bonding. The open [2+2] simple cubic solid should be a conductor, whereas the bcc solids are insulators. The most stable three-dimensional solid-state structure, an anisotropically compressed form of the bcc solid, has a HOMO-LUMO gap of approximately 2 eV and a larger binding energy than that of the proposed C(36) solid.     

Electron impact mass spectral fragmentation of chiral bisbenzoxazole,bisbenzothiazole and biscarbamide derivatives of 2,2-dimethyl-1,3-dioxolane

The mass spectrometric fragmentation behaviour of five pairs of (R,R)- and (S,S)-4,5-bis(benzoxazol-2-yl)-2,2-dimethyl-1,3-dioxolane derivatives, one pair of (R,R)- and (S,S)-4,5-bis(benzothiazol-2-yl)-2,2-dimethyl-1,3-dioxolanes, and three pairs of (R,R)- and (S,S)-N,N'-bis(2-hydroxyaryl)-2,2-dimethyl-1,3-dioxolane-4,5-dicarbamides, all important compounds for asymmetric catalysis (P. Jiao et al., Tetrahedron Asymmetry 2001; 12: 3081), has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization conditions. The spectral observations have been rationalized in terms of fragment ion structures and fragmentation mechanisms that will provide an aid to spectral interpretation for new compounds of this type.     

Au nanoparticle micropatterns prepared from self-assembled films

A kind of hybrid multilayer film based on mercaptobenzoic acid-capped Au nanoparticles (MBA-Au-NPs) and photoreactive nitrodiazoresin (NDR) has been fabricated via electrostatic self-assembly. Upon exposure to UV light, the initial ionic bonds between the layers of the film convert into covalent bonds and the film stability toward polar solvents, salt, or surfactant solutions increases significantly. The micropatterned NDR/MBA-Au-NP film with the covalently linked architecture was formed by selecting exposure of the film through a photomask and later developed in sodium dodecyl sulfate (SDS) aqueous solution. The metallic Au-NP micropatterns, furthermore, are produced by sintering the micropatterned NDR/MBA-Au-NP film at 550 degrees C, at which the organic components are removed completely. The well-defined micropatterns were characterized with atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), microscope with a charge-coupled device (CCD) camera, and X-ray photoelectron spectroscopy (XPS).     

Solution self-assembly, spontaneous deprotonation, and crystal structures of bipyrazolate-bridged metallomacrocycles with dimetal centers

A series of nanosized cavity-containing bipyrazolate-bridged metallomacrocycles with dimetal centers, namely, {[(bpy)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene), Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(phen)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(bpy)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(phen)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(bpy)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], and {[(phen)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,] (where bpy=2,2'-bipyridine and phen=1,10-phenanthroline) have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. These complexes, with weak Pd(II)...Pd(II) or Pt(II)...Pt(II) interactions, have been characterized by elemental analysis, 1H and 13C NMR, cold-spray ionization or electrospray ionization mass spectrometry, UV-visible spectroscopy, and luminescence spectroscopy. Complexes and have also been characterized by single-crystal X-ray diffraction analysis.     

Ln2O3/Al2O3催化酯化合成邻苯二甲酸二辛酯

Ｌｎ_２Ｏ_３／Ａｌ_２Ｏ_３催化酯化合成邻苯二甲酸二辛酯陈其瑞，张凤美，罗明润，焦肇林（安徽师范大学化学系，芜湖２４１０００）关键词稀土氧化物，担载催化剂，催化酯化，邻苯二甲酸二辛酯邻苯二甲酸二（２－乙基己醇用酯（Ｄｉｏｃｔｙｌｐｈｔｈａｌａｔｅ）是一...     

Syntheses,Characterization and Crystal Structures of Three Structurally Similar Dinuclear Schiff Base Cadmium(II) Complexes with Bridging Azide or Thiocyanate Ligands

Three novel Schiff base cadmium(II) complexes, derived from the end‐on (μ‐1,1‐N₃) azide or end‐to‐end (μ‐1,3‐NCS) thio cyanate bridges and similar tridentate Schiff base ligands, have been synthesized under similar synthetic procedures and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Cd₂(L1)₂(N₃)₂(μ‐1,1‐N₃)₂] ( 1 ), the dinuclear double end‐on azide‐bridged [Cd₂(L2)₂(N₃)₂(μ‐1,1‐N₃)₂] ( 2 ), and the dinuclear double end‐to‐end thiocyanate‐bridged [Cd₂(L3)₂(NCS)₂(μ_1,3‐NCS)₂] ( 3 ), where L1, L2 and L3 are three similar tridentate Schiff bases obtained by condensation of 2‐pyridylaldehyde with N,N‐diethylethane‐1,2‐diamine, of 2‐pyridylaldehyde with N‐isopropylethane‐1,2‐diamine, and of 2‐pyridylaldehyde with N,N‐dimethylpropane‐1,3‐diamine, respectively. Each cadmium(II) centre in the complexes is in a distorted octahedral coordination. There is a crystallographic inversion centre in each of the complexes. The similar small ligands used as the secondary ligands in the preparation of the cadmium(II) complexes with similar Schiff bases can result in similar structures.     

A facile route to vinyl- and arylphosphonates by vinyl and aryl radical trapping with (MeO)3P

The generation of vinyl or aryl radicals under classical, thermal AIBN/n-Bu(3)SnH conditions at 80 degrees C in the presence of an excess of (MeO)(3)P gives rise to the corresponding vinyl- or arylphosphonates in good yields. This approach complements the photochemical reactions of the same systems previously used. Reactions with the individual stereoisomers of MeCH=CHMeBr (thermal AIBN/n-Bu(3)SnH conditions) afford a radical-equilibrated 96/4 E/Z ratio of vinylphosphonates. Substitution of (TMS)(3)SiH for n-Bu(3)SnH yields an approximately 1/1 ratio of separable E and Z vinylphosphonate diastereomers.