钴(II)离子阴极还原的研究

研究Co~(2+)离子的阴极还原,主要是由于钴的湿法冶金和电镀生产的需要,以及理论研究上的兴趣.研究表明,钴离子的阴极还原过程是复杂的,很大程度上取决于电解液的酸度.Simonova 和Rotinyan 根据pH=2.5-4的实验数据,提出了二电子还原和分步还原平行进行的钴还原机理,用以解释85—150mV 的塔费尔斜率,这实际上反映了酸度对钴还原的影响.Epelboin 和Wiart 根据阴极极化特征和阻抗分析,认为Co~(2+)离子还原时可能     

芳基与烷基亚砜钯(II)配合物π反馈效应的DFT研究

应用DFT方法对二苯基亚砜(DPSO)和二己基亚砜(DHSO)的钯(II)配合物进行了理论计算。结果表明中心金属钯与亚砜之间存在d-π^*反馈键，而且二苯基亚砜钯(II)配合物中的π反馈键比二己基亚砜钯(II)配合物强，即亚砜的取代基对其钯(II)配合物的π反馈键有显著的影响。以BHandH/6-31+G^**(Pd，3-21G^*)//BHandH/6-31G^*(Pd，3-21G^*)方法对相应的亚砜钯(II)配合物进行单点计算时，配合物trans-PdCl₂(DPSO)₂ 的π反馈键轨道能为-10.695 eV，而trans-PdCl₂(DHSO)₂的π反馈键轨道能量为-10.320 eV。利用电子给体NH₃或电子受体CO配位体置换亚砜钯(II)配合物里的一个亚砜配体后，Pd(II)-DHSO配合物的Pd-S配位键长的变化明显小于Pd(II)-DPSO配合物的Pd-S配位键长变化值，进一步说明在Pd-DPSO配合物中的π反馈效应强于相应的Pd-DHSO配合物。     

四氯合钯(II)喹诺酮配合物的合成及与DNA的作用和抗增殖活性

在酸性条件下, 分别合成了四氯合钯(II)离子与2种喹诺酮(诺氟沙星, NFLX＝C16H18N3O3F; 环丙沙星, CPLX＝C17H18N3O3F)离子形成的配合物(NFLXH)2[PdCl4]•2H2O (1)和(CPLXH)2[PdCl4]•2H2O (2). 用元素分析、IR、UV以及摩尔电导测定等方法对其进行了表征. 配合物1的晶体结构经X射线单晶衍射确定, 结构参数: 三斜晶系, P-1空间群, a＝0.84561(17) nm, b＝0.94191(19) nm, c＝1.2832(3) nm; α＝111.26(3)°, β＝97.23(3)°, g＝96.38(3)°, V＝0.9312(4) nm3, Z＝1, 最后吻合因子R＝0.040, wR＝0.088. 利用紫外光谱法、荧光光谱法对配合物与小牛胸腺DNA (ct-DNA)的作用进行了研究, 研究表明, 配合物对DNA的作用模式为插入作用, 与DNA的结合常数Kb分别为: Kb(1)＝2.06×104, Kb(2)＝2.43×104. 其后测试了配合物对体外肿瘤细胞的抗增殖活性. 经采用四甲基偶氮唑蓝分析法(MTT法)测试后发现配合物1和2对人肺腺癌A549细胞、人原髓细胞白血病HL-60细胞的增殖抑制作用显著强于相应的喹诺酮分子本身, 其中配合物2对人肺腺癌A549细胞增殖有明显的抑制作用, 抑制率可高达(95.4±3.7)%, 半数抑制浓度(IC50, 72 h)为(124.5±10.3) μmol•L－1.     

双吡唑桥联的大环状钯(Ⅱ)配合物的合成与结构(英)

A dipyrazol-bridged macrocyclic palladium(Ⅱ) complex [{Pd(en)}₄L₄](NO₃)₈ (en=ethylenediamine, L=3,3′,5,5′-tetramethyldipyrazol) 1 was prepared in water through a [4+4] macrocyclization of cis-(ethylenediamine)Pd(Ⅱ) nitrate and the neutral form of the dipyrazol ligand 3,3′,5,5′-tetramethyldipyrazol. This cationic palladium macrocycle is highly distorted rather than a planar macrocycle and can hold eight nitrate anions around the macrocyclic framework through both hydrogen bonding and electrostatic interactions. CCDC: 192017.     

三元配合物钯(II)-联喹啉-丙二酸根的合成及其生物活性研究

合成了三元配合物 [Pd(biqu) (mal) ]·H2 O (biqu为 2 ,2′ 联喹啉 ,mal2 -为丙二酸根 ) .测定了配合物对肺腺癌细胞AGZY 83a的抑制活性 ,IC50 值为 2 1 9μg/mL .用荧光光谱、紫外光谱和圆二色谱测定了配合物与鱼精DNA的作用规律 .求出配合物与DNA的键合常数KM 为 2 0 3× 10 8.测定了配合物与pBR3 2 2质粒DNA作用的凝胶电泳图谱 .多种实验结果表明 ,配合物主要以插入方式与DNA发生键合作用 .     

铜(II)与四(间甲基)苯基卟啉镉(II)取代反应动力学

用分光光度法研究了二甲亚砜溶液中, 氯化铜与meso-四(间甲基)苯基卟啉镉(Ⅱ)(Cd(Ⅱ)P)亲电取代反应的动力学. 讨论了影响反应的因素, CuCl_2+Cd(Ⅱ)P→Cu(Ⅱ)P+CdCl_2提出了反应机理并进行了验证. 用AST286微机对实验数据进行非线性最小二乘法拟合, 得到拟合曲线及似平衡步的平衡常数K及其它基元步骤的速率常数k_1, k_(-1), k_2. 研究了温度对反应的影响, 求得似平衡步的△_rH_m~-θ-, △_rS_m~-θ-及其它基元步骤的活化参数△~≠H_m, △~≠S_m.     

钯(II)与阿莫西林和氨苄西林相互作用的共振瑞利散射光谱及其分析应用

在酸性介质中加热, 使阿莫西林(AMO)和氨苄西林(AMP)等侧链含苄氨基的青霉素类抗生素发生降解, 其降解产物青霉胺和苄氨基青霉醛在pH 5左右的弱酸性介质中能进一步与钯(II)反应形成物质的量比为1∶1∶1的混配型三元配合物, 此时将引起共振瑞利散射(RRS)的显著增强, 并出现新的RRS光谱. 钯(II)与两种药物的反应产物具有相似的RRS光谱特征, 最大散射波长均位于370 nm. 在一定范围内散射增强(ΔI)与药物的浓度成正比. 该方法具有较高的灵敏度, 对于AMO和AMP的检出限(3δ)分别为18.0和15.4 ng•mL^－1. 此时侧链不含苄氨基的其他青霉素不产生类似反应, 并且也允许一定量的其它物质存在, 因此, 方法有较好的选择性, 可用于胶囊、片剂及血清、尿样中阿莫西林和氨苄西林的测定, 能获得较满意的结果.     

大环金属铜(II)、镍(II)配合物的模板合成与晶体结构

用模板法合成了1个大环金属铜(II)配合物[CuLCl₂]·3H₂O (1)和3个大环金属镍(II)配合物[NiLCl₂] (2)，[NiL](ClO₄)₂ (3)和[NiLH₂](ClO₄)₄ (4)(L=3,10-二乙基-1，3，5，8，10，12-六氮杂十四烷)，通过X-射线衍射单晶结构分析测定了它们的晶体结构。晶体结构显示：配合物1和2的金属离子与大环配体的4个氮原子及大环平面轴向的2个氯离子以八面体配位方式配位；配合物3和4的金属离子与大环配体的4个氮原子以平面正方形配位方式配位，配合物4的侧链氮原子的质子化导致侧链结构翻转，使得其侧链与大环平面共面。     

钯(II)与阿莫西林和氨苄西林相互作用的共振瑞利散射光谱及其分析应用

在酸性介质中加热, 使阿莫西林(AMO)和氨苄西林(AMP)等侧链含苄氨基的青霉素类抗生素发生降解, 其降解产物青霉胺和苄氨基青霉醛在pH 5左右的弱酸性介质中能进一步与钯(II)反应形成物质的量比为1∶1∶1的混配型三元配合物, 此时将引起共振瑞利散射(RRS)的显著增强, 并出现新的RRS光谱. 钯(II)与两种药物的反应产物具有相似的RRS光谱特征, 最大散射波长均位于370 nm. 在一定范围内散射增强(ΔI)与药物的浓度成正比. 该方法具有较高的灵敏度, 对于AMO和AMP的检出限(3δ)分别为18.0和15.4 ng•mL^－1. 此时侧链不含苄氨基的其他青霉素不产生类似反应, 并且也允许一定量的其它物质存在, 因此, 方法有较好的选择性, 可用于胶囊、片剂及血清、尿样中阿莫西林和氨苄西林的测定, 能获得较满意的结果.     

p-CH3C6H4SR型硫醚与钯(II)配合物热分解反应动力学

热重分析(TG)和微商热重法(DTG)广泛应用于各个研究领域,用非等温热重法测定固体化合物的热分解动力学参数已有报导.许多作者提出各种不同的数据处理方法.本文用的ρ-CH_3C_6H_4SR 型硫醚对钯的萃取具有选择性好、分配比高、气味较小、易溶于脂肪烃类溶剂、易于合成、是很有发展前途的一类萃取剂.我们合成五种ρ-CH_3C_6H_4SR(R:n-C_4H_9,n-C_6H_(13),n-C_8H_(17),n-C_(10)H_(21),n-C_(12)H_(25))型硫醚与钯(Ⅱ)的配合物,用TG-DTG 法研究它们的热分解过程,用微商法(Freeman-Carroll 方程)及积分法(Coats-Redfern 方程)获得了这些配合物的热分解动力学参数.     

Kinetics and mechanism of electroreduction of Pd(II) complexes

The kinetics and mechanism of processes of reduction of Pd(II) complexes with a number of inorganic (NH₃ , Cl^– , etc.) and organic (ethylenediamine, glycine, -alanine, etc.) ligands on a dropping-mercury electrode and a Pd electrode in solutions with various concentrations of ligands, hydrogen ions, and supporting electrolytes are reviewed. The nature of electrochemical and chemical steps of processes of reduction of various complexes of Pd(II) is discussed.Translated from Elektrokhimiya, Vol. 40, No. 12, 2004, pp. 1494–1502.Original Russian Text Copyright © 2004 by Kravtsov.     

Simultaneous Adsorptive Cathodic Stripping Voltammetric Determination of Nickel(II) and Cobalt(II) at an In Situ Bismuth‐Modified Gold Electrode

A study on the simultaneous determination of Ni(II) and Co(II) dimethylglyoximates (Ni‐DMG and Co‐DMG) through adsorptive cathodic stripping voltammetry at an in situ bismuth‐modified gold electrode (Bi‐AuE) is reported. The key operational parameters, such as Bi(III) concentration, accumulation potential and accumulation time were optimized and the morphology of the Bi‐microcrystals deposited on the Au‐electrode was studied. The Bi‐AuE allowed convenient analysis of trace concentrations of solely Ni(II) or of Ni(II) and Co(II) together, with cathodic stripping voltammograms characterized by well‐separated stripping peaks. The calculated limit of detection (LOD) was 40 ng L^?1 for Ni(II) alone, whereas the LOD was 98 ng L^?1 for Ni(II) and 58 ng L^?1 for Co(II), when both metal ions were measured together. The optimized method was finally applied to the analysis of certified spring water (NIST1640a) and of natural water sampled in the Lagoon of Venice. The results obtained with the Bi‐AuE were in satisfactory agreement with the certified values and with those provided by complementary techniques, i.e., ICP‐OES and ICP‐MS.     

甘氨酸修饰的Pt(111)电极上的氧还原

利用单晶旋转圆盘电极技术（Hanging Meniscus Rotating Disk Electrode,　HMRD）在硫酸和高氯酸溶液中分别研究了甘氨酸修饰的Pt(111)电极表面氧分子的电催化还原反应. 实验发现：在硫酸溶液中,经甘氨酸修饰的Pt(111)电极表面的氧还原活性明显提高,其中氧还原的半波电位与Pt(111)电极的相比正移约0.1 V,而在高氯酸溶液中,甘氨酸修饰的Pt(111)电极的活性几乎没有发生变化. 该实验结果表明：甘氨酸修饰的Pt(111)电极一方面抑制了SO₄^2-在电极表面的吸附,另一方面又能在电极表面提供相邻的空位供氧分子吸附. 通过与文献中报道的CN^-修饰的Pt(111)电极上的氧还原结果的对比,可以推测甘氨酸修饰的Pt(111)电极表面氧还原活性提高是由于甘氨酸在Pt(111)表面可能先被氧化成CN^-后吸附在电极表面,进而促进了氧分子的电催化还原反应.     

水系体系中CO2在稀土(Nd)(Ⅲ)双酞菁修饰电极上的电催化还原研究

探讨了CO_2在稀土(Nd)(Ⅲ)双酞菁修饰电极上的电催还原行为。通过滴涂法将稀土(Nd)(Ⅲ)双酞菁担载在玻碳电极上制备成它的修饰电极,在水溶液中利用循环伏安、红外光谱法等方法研究制备的修饰电极对CO_2的电催化还原性能。结果表明,所制备的稀土(Nd)(Ⅲ)双酞菁修饰电极对CO_2的电催化还原有较高的活性,还原电流随修饰量增加而变大,修饰电极的还原电流与溶液的pH值有关,随着pH值变大,还原峰向负方向移动。实验结果表明,稀土(Nd)(Ⅲ)双酞菁修饰电极对二氧化碳电化学还原具有很好的电催化活性,在该修饰电极上,CO_2可在较正的电位下被还原。     

Palladium(II) acetate‐catalyzed reduction of imines to the corresponding amines by triethylsilane

Reduction of a variety of imine compounds with triethylsilane in the presence of catalytic amounts of palladium(II) acetate in ethanol resulted in the formation of the corresponding amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.     

Kinetics and mechanism of the substitution reactions of some monofunctional Pd(II) complexes with different nitrogen-donor heterocycles

Substitution reactions of five monofunctional Pd(II) complexes, [Pd(terpy)Cl]⁺ (terpy = 2,2′;6′,2″-terpyridine), [Pd(bpma)Cl]⁺ (bpma = bis(2-pyridylmethyl)amine), [Pd(dien)Cl]⁺ (dien = diethylenetriamine or 1,5-diamino-3-azapentane), [Pd(Me₄dien)Cl]⁺ (Me₄dien = 1,1,7,7-tetramethyldiethylenetriamine), and [Pd(Et₄dien)Cl]⁺ (Et₄dien = 1,1,7,7-tetraethyldiethylenetriamine), with unsaturated N-heterocycles such as 3-amino-4-iodo-pyrazole (pzI), 5-amino-4-bromo-3-methyl-pyrazole (pzBr), 1,2,4-triazole, pyrazole, pyrazine, and imidazole were investigated in aqueous 0.10 M NaClO₄ in the presence of 10 mM NaCl using variable-temperature stopped-flow spectrophotometry. The second-order rate constants k₂ indicate that the reactivity of the Pd(II) complexes decrease in the order [Pd(terpy)Cl]⁺ > [Pd(bpma)Cl]⁺ > [Pd(dien)Cl]⁺ > [Pd(Me₄dien)Cl]⁺ > [Pd(Et₄dien)Cl]⁺. The most reactive nucleophile of the heterocycles is pyrazine, while the slowest reactivity is with pyrazole. Activation parameters were determined for all reactions and negative entropies of activation, ΔS^≠, supporting an associative mode of substitution. The reactions between [Pd(bpma)Cl]⁺ and 1,2,4-triazole, pzI, and pzBr were also investigated by ¹H NMR to define the manner of coordination. These results could be useful for better explanation of structure-reactivity relationships of Pd(II) complexes as well as for the prediction of potential targets of Pd(II) complexes toward common N-heterocycles, constituents of biomolecules and different N-bonding pharmaceutical agents.     

A New PVC-Membrane Electrode Based on a Macrocyclic Ionophore for Selective Determination of Ni (II) Ions

A poly(vinyl chloride)-based membrane of 3,4:12,13-dibenzo-1,6,10,15-tetraazacyclooctadecane with sodium tetraphenyl borate (NaTPB) as an anion excluder and dibutylphthalate (DBP), dibutylbutylphosphonate (DBBP), tris(2-ethylhexyl) phosphate (TEHP) and tributyl phosphate (TBP) as plasticizing solvent mediator was prepared and investigated as a Ni(II)-selective electrode. The best performance was observed with the membrane having the ligand-PVC-TEHP-NaTPB composition 1:4:1:1, which worked well over a wide concentration range (2.82 ×10⁻⁶−1.00 × 10⁻¹ M) with a Nernstian slope of 30.5 mV per decade of activity between pH 2.5–7.5. This electrode showed a fast response time of 18 s and was used over a period of 4 months with good reproducibility (S=0.4 mV). The selectivity coefficient over mono-, di- and trivalent cations indicate excellent selectivity for Ni (II) ions over a large number of cations. Anions such as Cl⁻ and NO₃⁻ do not interfere and the electrode also works satisfactorily in a partially non-aqueous medium. It has been used successfully for determination of Ni (II) in real samples.     

Determination of Amino Acids by Ru(bpy)_3~(2+) Cathodic Electrochemiluminescence with High Sensitivity

The unique cathodic electrochemiluminescence(ECL) emission of Ru(bpy)32+(bpy=2,2′-bipyridine) was observed via Nafion film at Au electrode[Au/Nafion/Ru(bpy)32+] at about 0.20 V(vs. Ag/AgCl) and applied to the determination of several amino acids without prior derivatization with high sensitivity. The cathodic electrochemilumi-nescence(ECL) exhibits the detection limits and linear ranges of several amino acids comparable to or better than those of capillary electrophoresis with conventional ECL detection method(at 1.10—1.20 V vs. Ag/AgCl) based on precolumn derivatization. The results suggest that the cathodic ECL is promising for the detection of amino acids in bioanalysis.     

钯含氮配合物催化烯烃芳基化反应的密度泛函研究

用密度泛函方法(DFT)研究了Pd(II)含氮配合物催化烯烃芳基化反应的机理. 结果表明, 该反应是放热的, 主要经历了对甲苯基对烯烃的迁移插入和β-H的还原消去. 对甲苯基对烯烃的迁移插入是反应的速率控制步骤和手性控制步骤. 理论预测的产物是与实验一致的(R)-2-甲基-2-苯基环戊酮.     

对位取代四苯基卟啉铜(II)的生成动力学及其它金属离子的影响

本文用Shimadzu UV-240紫外可见分光光度计对Cu(Ⅱ)与对位取代四苯基卟啉H_2(p-X)TPP(X=NO_2, (Cl,H,CH_3,OCH_3)在二甲亚砜溶剂中的生成动力学及镉(Ⅱ)离子对该反应的催化作用进行了系统研究, 提出了反应机理, 并观察了Hg(Ⅱ)、Pb(Ⅱ)等其它金属离子对此反应的影响。发现反应速率常数及平衡常数与Hammett取代常数σ值之间呈现良好的直线自由能关系。