苦玄参化学成分的研究——Ⅶ.-苦玄参苷IA和IB的结构

本文报道从具有抗肿瘤活性的苦玄参(Pic(?)afel-tarraeLour)提取物的 B 部分中分得两个新四环三萜苷——苦玄参苷(picfeltarraenin)ⅠA(1)和ⅠB(2).1和2经酸水解均得苦玄参苷元Ⅰ(3),经稀酸水解分别得次生苷4和5.根据1,2,4,5及它们衍生物的~1HNMR,~(13)CNMR 和 NICIMS 数据,证明1为3的3-O-β-D-[α-L-吡喃鼠李糖基(1→2)]-吡喃木糖苷,2为3的3-O-β-D-[α-L-吡喃鼠李糖基(1→2)]-吡喃葡萄糖苷.     

苦玄参化学成分的研究 VII.一苦玄参苷IA和IB的结构

本文报道从具有抗肿瘤活性的苦玄参(Picriafel-tarraeLour)提取物的B部分中分得两个新四环三萜苷-苦玄参苷(Picfeltarraenin)IA(1)和IB(2).1和2经酸水解均得警玄参苷元I(3),经稀酸水解分别次生苷4和5。根据1,2,4,5及它们衍生物的1HNMR,12CNMR和NICIMS数据,证明1为3的3-O-β-D[α-L-吡喃鼠李糖基(1→2)]-吡喃木糖苷,2为3的3-O-β-D-[α-L-吡喃鼠李糖基(1→2)]-吡喃葡萄糖苷。     

苦玄参化学成分的研究 ⅤⅢ.苦玄参苷Ⅱ的结构

从苦玄参(Picria fel-tarrae Lour)提取的有抗癌活性的B部分,在分离苦玄参苷IA和IB时,还分离到另一少量新苦味苷——苦玄参苷(Picfeltarraenin)Ⅱ(1).本文报道1的结构测定. 1经8％硫酸水解产生苦玄参苷元Ⅱ(2),所产生的糖经定性鉴定为D-葡萄糖和L-鼠李糖.根据1的FDMS所获得的准分子离子峰[M+Na+1]~+及元素分析,确定其分子式为C_(42)H_(66)O_(15),即1含一个葡萄糖和一个鼠李糖残基.1的~(13)C NMR谱中出现两个异头碳(anomeric carbon)信号,也符合上述推定.     

苦玄参化学成分的研究——Ⅴ.苦玄参苷元Ⅴ和Ⅵ的结构

木文报道苦玄参提取物中的抗肿瘤活性部分,经酸水解后又分得两个新四环三萜苷元,苦玄参苷元(picfeltarraegenin)Ⅴ和Ⅵ.根据其UV,¹H NMR,¹³C NMR,MS数据以及化学反应,证明苦玄参苷元Ⅴ和Ⅵ分别具有5和8的结构,5的结构经苦玄参苷元Ⅰ(1)的双乙酸酯(7)氧化成6而加以确证.     

苦玄参化学成分的研究——Ⅰ.苦玄参苷元Ⅰ的结构

从玄参科的苦玄参植物中分出一系列苦味苷的苷元.苦玄参苷元Ⅰ(1)是其主要成分.通过1及其衍生物的Uv,IR,¹HNMR,¹³CNMR及MS的谱学分析和若干化学反应确定1的结构为具有二氢呋喃酮边链的新型四环三萜.苦玄参苷经药理实验证明有抗癌活性.     

苦绳的寡糖成分

从苦绳(Drehea sinensis Himsl.)中分离得到三个新化合物:苦绳双糖苷(2a),苦绳三糖苷(3a)和苦绳四糖苷(4) 经化学反应和光谱分析证明其结构依次为:β-D-黄夹吡喃糖基-(1→4)-β-D-磁麻吡喃糖甲苷;β-D-葡葡吡喃糖基-(1→4)-β-D-黄夹吡喃糖基-(1→4)-α-D-夹竹桃吡喃糖甲苷和-β-D葡萄吡喃基-(1→4)-β-D-葡萄吡喃糖基-(1→4)-β-D-黄夹吡喃糖基-(1→4)-α-D-夹竹桃吡喃糖甲苷。     

苦玄参化学成分的研究——Ⅱ.苦玄参苷元Ⅱ和Ⅲ的结构

本文报道从苦玄参(Picria fel-tarrae Lour)提取物B中分得两个新化合物,苦玄参苷元(picfeltarraegenin)Ⅱ和Ⅲ。根据此两化合物的UV,IR,¹H NMR,¹³C NMR和MS数据以及化学反应,证明分别具有2和8的结构。     

苦玄参甙元Ⅰ—Ⅵ(1—6)和苦玄参酮(7)的结构

本文报导了从苦玄参(Picria fel-tarrae Lour)提取物中分得的一系列新的四环三萜化合物,苦玄参甙元Ⅰ—Ⅵ(1—6)和苦玄参酮(7)。根据它们的谱学数据(紫外光谱、红外光谱、~1H和~(13)C核磁共振谱和质谱)、X-射线衍射分析以及彼此间的化学联系,证明了苦玄参甙元Ⅰ—Ⅵ和苦玄参酮分别具有1-6和7的结构。     

苦玄参化学成分的研究——Ⅵ.苦玄参苷元2及有关化合物的立体化学

本文报道应用镧系位移试剂的~1HNMR进一步研究了苦玄参苷元2及有关化合物的立体化学,2,13,15,17和19的C_(24)为S构型。14,16,18和20为R构型。从Gratiola officinalisL.所得的16-hydroxygratiogenin(23a)和gratiogenin (23b)的C_(20)和C_(24)均首次确定为S的构型。     

小花玄参化学成分的定性研究及总黄酮含量的测定

采用不同极性溶剂提取小花玄参中的化学成分,应用植物化学成分的系统分析法定性研究,并对其总黄酮含量进行测定.结果表明,小花玄参中含有氨基酸、多肽和蛋白质、糖及苷类、有机酸、鞣质、皂苷、甾体或三萜类、黄酮、酚类、挥发油和油脂、强心苷和生物碱等化学成分,未检出蒽醌及香豆素与萜类内酯;小花玄参中总黄酮的含量为5.689%(56.89mg/g).该结果可为小花玄参化学成分的分离纯化、药理研究以及开发利用等提供基础依据.     

Enhancement of the activity of a neodymium catalyst for the synthesis of stereoregular polyisoprene

A new ligand based on two pyrazole cycles linked with each other was synthesized. Its interaction with Cu(II), Ni(II), Co(II), Mn(II), Cr(III), Zn(II), and Cd(II) cations in ethanol was studied by the spectrophotometric method.     

On the mechanism of electroreduction of sulphur-containing ligands induced by the electroreduction of transition metal cations

The large scale electrolysis of Zn(II), Cd(II), Hg(II), Cu(II), Ni(II), Co(II), Co(III), Fe(II), Mn(II), Cr(II), Cr(III), Bi(III), In(III) and Sb(III) at mercury electrodes in presence of mercaptoacetic acid, 3-mercaptopropionic acid, cysteine and thiourea was carried out and the products were investigated. In case of transition metal ions the catalytic reduction of organic compounds resulting in the formation of sulphide ions was found. There are two possible ways of the production of these ions: (i) consisting in the formation of a complex between transition metal ion and organic ligand which is subsequently, reduced, and (ii) direct electroreduction of organic compound on the electrode modifiied by the deposition of metal and metal sulphide. For both cases the mechanism of electroreduction was discussed.     

Indirect cerimetric determination of gold at the milligram level

Summary A rapid volumetric method has been worked out for the indirect determination of 0.25–2.5 mg of gold in presence of many common ions. It is based on the reduction of gold(III) to metal with excess of cobalt(II) in the presence of 1,10-phenanthroline at pH 3 and 50°, and estimation of the unreacted cobalt(II) in the filtrate by visual, potentiometric or biamperometric titration with standardized cerium(IV) sulphate solution. It has been found that there is no interference from Ni(II), Pb(II), Zn(II), Cd(II), Mn(II), Mg(II), Ca(II), Al(III), Cr(III), Ti(IV), V(V) and W(VI). Interference due to Pd(II) and Ag(I) can be eliminated. Fe(III), Cu(II), Mo(VI), Hg(II) and Pt(IV) interfere, even present in small amounts.

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Zusammenfassung Ein schnelles maßanalytisches Verfahren zur indirekten Bestimmung von 0,25–2,5 mg Gold in Gegenwart vieler Ionen wurde ausgearbeitet. Es beruht auf der Reduktion zu metallischem Gold mit überschüssigem Kobalt(II) in Anwesenheit von 1,10-Phenanthrolin bei pH 3 und 50°. Die Rückbestimmung des unverbrauchten Kobalts im Filtrat erfolgt durch potentiometrische oder biamperometrische Titration mit Cer(IV)sulfat. Ni(II), Pb(II), Zn(II), Cd(II), Mn(II), Mg(II), Ca(II), Al(II), Cr(III), Ti(IV), V(V) und W(VI) stören nicht. Eine Störung durch Pd(II) oder Ag(I) kann man ausschalten. Fe(III), Cu(II), Mo(VI), Hg(II) und Pt(IV) stören auch in geringen Mengen.

     

Thermal Properties of N-ethyl-N-phenyl-Dithiocarbamates and Their Influence on the Kinetics of Cure

The thermal properties (in the temperature range of 100–250°C) of N-ethyl-N-phenyldithiocarbamatecomplexes of Zn(II), Co(III), Ni(II), Cu(II) and Pb(II) and their influence on the kinetics of cure have been studied by differential scanning calorimetry (in nitrogen). It was found that Zn(II), Co(III) and Pb(II) dithiocarbamates melted without further effects, while the melting of Ni(II) and Cu(II) dithiocarbamates is accompanied with decomposition. From the kinetic point of view, the dithiocarbamates decrease the values of the reaction order and the values of rate constants follow this order (with respect to the metal ion): Zn(II)<Cu(II)<Pb(II)<Ni(II)<Co(III).This revised version was published online in November 2005 with corrections to the Cover Date.     

Influence of the macrocycle structure on the ability of Co(II)-porphyrins to oxidize in the presence of organic bases

Abstract

By spectrophotometric titration, ¹H NMR and cyclic voltammetry the processes of Co(II)-5,10,15,20-tetraphenylporphyrin, Co(II)-5,10,15,20-tetraphenyl-2,3,7,8,12,13,17,18-tetrabenzoporphyrin, Co(II)-2,3,7,8,12,13,17,18-octaphenyl-5,10,15,20-tetraazaporphyrin, Co(II)-2,3,7,8,12,13,17,18-octa(4-bromphenyl)-5,10,15,20-tetraazaporphyrin and Co(II)-2,3,7,8,12,13,17,18-octa(4-nitrophenyl)-5,10,15,20-tetraazaporphyrin interaction with imidazole (Im) in benzene in the presence and absence of atmospheric oxygen has been investigated. If the Co(II)-porphyrins with high E_pc upon complexation with the imidazole form stable mono-axial complexes Co(II)P(Im), then the Co(II)-porphyrins with low E_pc are oxidized into low-spin six-coordinate Co(III)-porphyrins with formation of bis-axial complexes Co(III)P(Im)₂. The thermodynamic and kinetic parameters of the coordination and oxidation processes have been calculated and corresponding structural correlations have been carried out.     

镍(II)-丁二酮肟体系极谱催化波的机理研究

研究了镍(II)-丁二酮肟(DMG)体系极谱催化波的行为, 这一体系的极谱催化波可用于生物及岩矿中测定痕量镍和同时测定痕量镍、钴, 并对照研究了Co(II)-DMG体系和Ni(II)-DMG体系的机理.     

Coordination features of a terpyridine-containing polyamine receptor. Effect of protonation on the photophysical properties of the complexes

The synthesis of the new terpyridine-containing macrocycle 2,6,10,14-tetraaza[15](6,6')cyclo(2,2':6',2')terpyridinophane (L) is reported. The ligand contains a tetraamine chain linking the 6,6' positions of a terpyridine unit. A potentiometric, (1)H NMR, UV-vis spectrophotometric and fluorescence emission study on the basicity properties of in aqueous solutions shows that the first four protonation steps occur on the polyamine chain, while the terpyridine nitrogens are involved in proton binding only in the last protonation step at strongly acidic pH values. Cu(II), Zn(II), Cd(II) and Pb(II) complexation was studied in aqueous solution by means of potentiometric, spectrophotometric and spectrofluorimetric measurements. Cu(II) and Zn(II) can form both mono- and dinuclear complexes in solution, while the larger Cd(II) and Pb(II) give only mononuclear complexes. In the [ML](2+) complexes (M = Zn(II) or Cd(II)) the metal is unequivocally bound to the terpyridine unit. Some amine groups are not coordinated and can quench the fluorescence emission of the terpyridine unit thanks to an electron transfer process. Protonation of the unbound amine groups inhibits the eT process, affording fluorescent [MLH(x)]((2+x)+) complexes.     

Complexing ability of the substituted oxathiacrown ethers with vicinal arrangement of the sulfur atoms

Complexing ability of crown ethers opens new ways of designing selective extragents and sensitive receptors to various metal cations. The structure of the oxathiacrown ether complexes with Ag(I), Pb(II), Hg(II), Cd(II), Ni(II), Pd(II) ions was investigated using the methods of mass spectrometry and ¹H NMR spectroscopy. Formation of 1:1 and 2:1 ligand-metal complexes was established.     

Influence of the nature of the metal ion on the rate of reduction of coordinated azomethine group

The kinetics of reduction of the azomethine bond in various Schiff bases and their transition metal complexes with sodium borohydride in dimethylformamide and ethanol solutions was studied. The reduction rate depends on both the structure of the starting Schiff bases and the nature of the metal ion. In transition metal N-phenylsalicylaldiminates, the rate of reduction of the azomethine group increases in the order Zn(II) < Ni(II) < Cu(II) < Co(II) < VO(II) < Mn(II). Similar trend is observed in other series of metal complexes with Schiff bases. The revealed trends are opposite to the Irving-Williams series of stability of complexes. This fact suggests that the major factor affecting the rate of reduction of the coordinated azomethine bond is the strength of its bonding with the metal ion. Depending on particular metal ion, the complexation can either decelerate or accelerate the reduction.     

Ion-pair formation of a copper(II)-ammine complex with an anionic surfactant and the recovery of copper(II) from ammonia medium by the surfactant-gel extraction method.

The extraction and separation of copper(II), zinc(II), cobalt(II), and cadmium(II) were investigated. Both copper(II) and zinc(II) formed ammine-complexes, while cadmium(II) and cobalt(II) formed hydroxide precipitates in an ammonia medium. By the addition of sodium dodecylsulfate (SDS), a copper(II) complex formed an ion-pair (copper-ammine-DS), which was extracted into the SDS phase. However, a zinc(II) complex did not form an ion-pair, and was soluble in water. Copper(II) ion was recovered by stripping (back-extraction) after the addition of hydrochloric acid. This method was applied to the separation of copper(II) in a brass alloy.