Synthesis and Catalytic Activity of a Two-core Ruthenium Carbene Complex: a Unique Catalyst for Ring Closing Metathesis Reaction

The reaction of a ruthenium carbide complex RuCl2(C:)(PCy3)2 with [H(Et2O)x]+[BF4]– at a molar ratio of 1:2 produced a two-core ruthenium carbene complex, {[RuCl(=CHPCy3)(PCy3)]2(μ-Cl)3}+·[BF4]–, in the form of a yellow-green crystalline solid in a yield of 94%. This two-core ruthenium complex is a selective catalyst for ring closing metathesis of unsubstituted terminal dienes. More importantly, no isomerized byproduct was observed for N-substrates when the two-core ruthenium complex was used as the catalyst at an elevated temperature(137 °C), indicating that the complex is a chemo-selective catalyst for ring closing metathesis reactions.     

Sonochemical Synthesis of Three-dimensional Aggregates of Pd Nanoparticles with High Electrocatalytic Activity Towards Ethanol Oxidation

Flower-like aggregates composed of （4.0±0.8） nm palladium（Pd） nanoparticles were prepared via ultrasonics in the palladium（Ⅱ） chloride（PdCl2） H2O/EtOH（5/1,volume ratio） solution with the addition of a quantity of poly（vinyl pyrrolidone）（PVP） and sodium dodecyl sulfonate（SDS）.The morphologies,crystal structures and the optical properties of the flower-like Pd nanostructures were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,selected area electron diffraction（SAED） and UV-visible absorption spectroscopy,respectively.The mechanism of sonochemical reduction of Pd（Ⅱ） ions was also investigated.The results show that the molar ratio of PVP to SDS affected the formation of the flower-like aggregates of Pd nanoparticles.Moreover,the electrocatalytic properties of Pd aggregates modified glassy carbon electrode for ethanol oxidation were also investigated by cyclic voltammetry（CV）.This material exhibits remarkable electrocatalytic activity for ethanol oxidation in 1 mol/L KOH and appears as a promising candidate to be applied in direct ethanol fuel cells.     

A Dinuclear Ruthenium(II) Schiff Base Complex with Dissimilar Coordination: Synthesis,Characterization, and Biological Activity

A dinuclear Schiff base Ru^II complex derived from 5‐chlorosalicylaldehyde and 2‐aminopyridine was synthesized. The structure of the compound was analyzed by mass spectrometry as well as IR, UV/Vis, and ¹H NMR spectroscopy, along with chemical analysis,as well as magnetic, cyclovoltammetric and conductivity measurements. Two Ru^II atoms are octahedrally coordinated by azomethine and pyridine nitrogen atoms from two tridentate monobasic Schiff bases and bridging phenol oxygen atoms. The formula of the complex is [Ru₂L₂Cl₂(Et₂NH)(H₂O)] [L = N‐(2‐pyridyl)‐5‐chlorosalicylideneimine and Et₂NH = isodiethylamine]. The Ru^II atoms in the dinuclear neutral complex species have different coordination environments, RuN₃O₂Cl and RuN₂O₃Cl. Interaction with CT DNA showed moderate hydrophobic binding. The compound demonstrates strong activity against methicillin‐resistant Staphylococcus aureus, methicillin‐sensitive Staphylococcus aureus, and especially Enterococcus faecalis. Microbiological tests showed significant inhibition of growth and ability to kill pathogens, similar or even improved compared to reference antibiotics vancomycin.     

胺基膦钌卡宾化合物的合成及催化烯烃复分解反应

合成并表征了一类含新型胺基膦配体的Grubbs二代型钌卡宾烯烃复分解催化剂[RuCl₂(H₂IMes)·(R¹HNPR²₂)(=CHPh)], 采用核磁共振波谱和单晶X射线衍射确定了催化剂的结构. 在室温条件下, 以N,N-二烯丙基-对甲苯磺酰胺的关环复分解反应(RCM)为模型, 考察了不同胺基膦配体对钌卡宾催化反应速率的影响. 结果表明, G2?1表现出最佳的催化活性. 通过底物研究发现, G2?1催化剂(摩尔分数, 1%)对双端烯及多端烯的RCM反应具有较好的活性和官能团适应性, 产物收率均>95%; G2?1催化剂同样适用于同(异)端烯底物的交叉复分解反应(CM), 其催化苯乙烯与3-苯氧基丙烯的CM反应时产物收率高达92%.     

一个新型钌(Ⅱ)配合物的合成、表征与DNA的键合及溶剂变色性质

合成和表征了1个新的钌(Ⅱ)配合物[Ru(bpy)₂(dpapz)](ClO₄)₂,其中bpy=2,2'-联吡啶,dpapz=联吡啶并[3,2-a:2,'3-'c]-6-氮杂-吩嗪.通过紫外可见光谱、荧光光谱、与溴化乙锭的竞争键合实验和粘度测量研究了该配合物与小牛胸腺DNA的键合性质,并研究了该配合物的紫外可见光谱和荧光光谱的溶剂变色性质.结果表明,该配合物是具有键合常数Kb=6.9×10⁵L/mol(50mmol/LNaCl)的DNA嵌入键合试剂和优良的荧光溶剂传感分子.     

Ir/CNTs催化剂的制备及对氨的电催化氧化

分别以碳纳米管(CNTs)和XC-72活性碳为载体制备了Ir/CNTs和Ir/C催化剂. X射线衍射(XRD)结果显示, CNTs拥有更高的石墨化程度. 电化学研究结果表明, 与Ir/C催化剂相比, Ir/CNTs对氨氧化具有更高的电流密度、更低的起始氧化电位和更好的稳定性. 同时, Ir/CNTs催化剂对氨检测的线性范围更宽, 灵敏度更高, 检出限更低.     

二氧化钛与碳化钨纳米复合材料制备及其对甲醇的电催化氧化活性

以市售纳米二氧化钛(TiO2)为载体,六氯化钨为钨源,将浸渍法与原位还原碳化技术相结合制备了核壳结构碳化钨(WC)/TiO2纳米复合材料;应用X射线衍射分析、透射电子显微镜、高分辨扫描透射成像和X射线能量散射谱等手段对样品晶相、形貌、微结构和化学组成等特征进行了表征.结果表明,样品的晶相由金红石型TiO2、Ti4O7、WC、W2C和WxC构成,钨碳化物负载于钛氧化物外表面,构成比较典型的核壳结构.采用三电极体系和循环伏安法测试了样品在碱性溶液中对甲醇的电催化氧化活性,结果表明,相比于纯碳化钨和二氧化钛,复合材料的电催化活性得到了明显的提升.样品电催化活性的提升与前驱体钨钛摩尔比、还原碳化时间、核壳结构壳层的完整性和晶相组成以及核壳结构中二氧化钛和碳化钨之间的协同效应有关.这说明金红石是能够提升碳化钨电催化氧化活性的载体材料之一.     

亚胺膦钌配合物RuCl2P2N2的合成和催化性能

ＲｕＣｌ２（Ｐｈ３Ｐ）４或ＲｕＣｌ２（ＤＭＳＯ）４在甲苯中直接与等摩尔的亚胺膦配体Ｎ，Ｎ－双－［邻－（二苯基膦苯亚甲基）］乙二胺（Ｐ２Ｎ２）在甲苯中回流反应，高产率地合成了反式配位的双亚胺双膦钌配合物ｔｒａｎｓ－ＲｕＣｌ２Ｐ２Ｎ２．在温和条件下，该配合物作为新型催化剂有效地催化α，β－不饱和酸和几种功能团烯烃的选择加氢反应．讨论了可能的催化活性物种．     

Electrocatalytic Activity of Pt/C Electrodes for Ethanol Oxidation in Vapor Phase

Introduction The selective oxidation of ethanol to acetaldehydeis of special interest in the areas where biomass-basedeconomics are under development since acetaldehydecan be used for the syntheses of other basic chemicalssuch as acetic acid, acetic anhydride,n-butanol,etc.[1—6]. With the advancement of fuel cell technologyand electrocatalysis stimulated by the world energy andraw material situation, some special opportunities havebeen provided for investigating electrosynthesis of or-ganic c…     

Study on Electrocatalytic Activity of Platinum for Hydrogen Oxidation in Acidic Solution by Scanning Electrochemical Microscopy

The electrocatalytic activity of platinum for hydrogen oxidation in 0.01 M H₂SO₄ + 0.1 MNa₂SO₄ solution has been investigated by scanning electrochemical microscopy (SECM) technique. The cyclic voltammogram (CV), approach curve, area scan imaging and chronoamperometric methods have been used. The results indicate that the imaging capability of the SECM feedback mode can be used more efficiently to visually identify materials' electrocatalytic activity, compared with the approach curve method for identification of the conductive or insulating nature of a surface. The SECM imaging method has demonstrated the effects of Pt substrate potential on the electrocatalytic oxidation of hydrogen under a constant tip potential. It is found that the more positive the Pt substrate potential, the lower the electrocatalytic activity of the Pt. Furthermore, the chronoamperometric results support the variation of the electrocatalytic activity with the Pt substrate potential as well.     

Properties of Dendrimer‐Encapsulated Pt Nanoparticles Doped Polypyrrole Composite Films and Their Electrocatalytic Activity for Glucose Oxidation

A type of novel electroanalytical sensing nanobiocomposite material was prepared by electropolymerization of pyrrole containing poly(amidoamine) dendrimers‐encapsulated platinum nanoparticles (Pt‐PAMAM), and glucose oxidase (GOx). The Pt nanoparticles encapsulated in PAMAM are nearly monodisperse with an average diameter of 3 nm, and they provide electrical conductivity. Polypyrrole acts as a polymer backbone to give stable and homogeneous cast thin films, and it also defines the electrical conductivity. Both Polypyrrole and PAMAM can provide a favorable microenvironment to keep the bioactivity of enzymes such as glucose oxidase. The homogeneity of GOx/Pt‐PAMAM‐PPy nanobiocomposite films was characterized by atomic force microscopy (AFM). Amperometric biosensors fabricated with these materials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and amperometric measurements in the presence of hydrogen peroxide or glucose. All those show the resultant biosensor sensitivity was strongly enhanced within the nanobiocomposite film. The optimized glucose biosensor displayed a sensitivity of 164 μA mM^?1 cm^?1, a linear range of 0.2 to 600 μM, a detection limit of 10 nM, and a response time of <3 s.     

Electrocatalytic Oxidation of Tryptophan at Gold Nanoparticle‐Modified Carbon Ionic Liquid Electrode

The electrochemical behavior of tryptophan was studied at the carbon ionic liquid electrode (CILE) modified with gold nanoparticle (GNP). This electrode has a stable and excellent response toward tryptophan. Under optimum experimental conditions, the calibration curve was linear in the tryptophan concentration range of 5 to 900 µM with an excellent correlation coefficient (0.995). The experimental limit of detection was 4 µM. Contrary to many other electrodes, the oxidation of tryptophan on GNP/CILE does not result in electrode fouling. GNP/CILE has been effectively applied to the determination of tryptophan in composite amino acid injection.     

钌配合物[Ru(bpy)2(PNT)]2+的合成、表征及与DNA相互作用研究

以cis-Ru(bpy)2Cl2·2H2O与PNT为原料合成钌(Ⅱ)多吡啶配合物[Ru(bpy)2(PNT)]2+(bpy=2,2’-联吡啶, PNT=2-[4’-(5-四唑基)苯基]咪唑-[4,5-f][1,10]邻菲咯啉), 通过元素分析、质谱和核磁共振波谱对该化合物进行了结构表征. 利用紫外-可见吸收光谱、荧光光谱、热变性和黏度实验研究了配合物与CT-DNA的相互作用, 实验结果表明, 该配合物以部分插入模式与DNA结合.     

WC/天然沸石纳米复合材料的制备与电催化活性

以天然沸石为载体,偏钨酸铵为钨源,将机械化学法与原位还原碳化技术结合,制备了碳化钨与天然沸石的纳米复合材料.制备过程中,首先对天然沸石进行预处理,然后按硅钨摩尔比为2:1配置偏钨酸铵与沸石混合物,经机械球磨得到三氧化钨与沸石复合前驱体,再将前驱体在管式炉内1173K温度下,在CH4与H2混合气氛中还原碳化即得碳化钨与沸石的纳米复合材料.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线能量散射谱(EDS)分别对样品的晶相、形貌、微结构和化学组成进行了表征.结果表明,样品主要由一碳化钨、碳化二钨、石英、丝光沸石、斜发沸石等物相组成.其中,一碳化钨晶粒约为30nm,碳化二钨的晶粒约为20nm.应用粉末微电极测试了样品在中性溶液中对对硝基苯酚的电催化活性.结果表明,在中性溶液中样品对对硝基苯酚电催化活性优于介孔空心球状碳化钨,样品的电还原催化活性与其WC的质量分数和WC与W2C的质量比相关.碳化钨与沸石构成复合材料后,两者具有明显的协同效应.     

Isolation and Characterization of a Dimeric Ruthenium(II) Complex. An Intermediate in the Ruthenium-Catalyzed Oxygen Oxidation of Thioethers to Sulfoxides

Complexes of the type Ru¹¹X₂(MeSO)_{2 or 3}(PR₃) are excel1ent catalysts for the selective oxygen oxidation of thioethers to sulfoxides. The complex RuCl₂(Me₂SO)₃(PPh₃) is an example of such a catalyst, and its solution chemistry under simulated catalytic conditions reveals that only one detectable complex is present. This presumed catalytic complex has been isolated and characterized by ¹H, ¹³C, and ³¹P NMR and by an x-ray structure determination to be the chlorotri-μ-chlorotris(dimethyl sulfoxide)bis(triphenylphosphine) diruthenium, 2. Single crystals of 2 are monoclinic with space group P _21/c with a = 16.662(3)Å, b = 16.576(3)Å, c = 19.282(3)Å, and β =98.86(1)°. The structure was refined to R = 0.053(R_w = 0.069) by using 5186 unique reflections. Both Ru centers are coordinated in a distorted octahedral fashion having three μ-bridged chlorine atoms shared between them. RU₁ possesses three terminal ligands, one chloride, one triphenylphosphine and a dimethyl sulfoxide. RU₂ is terminally bonded to two Me₂SO centers and one triphenylphosphine. The μ-bridged chlorine atoms are bonded in an asymmetric fashion due to the differing trans-influences of the Cl^?, (CH₃)₂SO and PPh₃ ligands bonded to the metal centers. RU-μCl distances range from 2.436(2)Å to 2.490(2)Å, and Ru-S distances from 2.205(2)Å to 2.269(2)Å.     

碳化钨与蒙脱石纳米复合材料的制备与电催化活性

具有类铂催化性能的碳化钨(WC)催化材料是当前研究的热点与难点. 本文以六氯化钨为钨源, 用剥离后的蒙脱石片层为载体, 将化学浸渍法与原位还原碳化法技术相结合制备了碳化钨与蒙脱石纳米复合材料; 复合材料由碳化钨、碳化二钨(W₂C)和蒙脱石(MMT)组成, 碳化钨呈颗粒状分散或呈层状负载于MMT外表面; 样品的晶相组成与其还原碳化时间有关; 样品的微结构特征与前驱体中钨与蒙脱石的比例有关. 采用三电极体系和循环伏安法测试了样品在酸性溶液中对甲醇的电催化氧化性能, 结果表明, 碳化钨与蒙脱石复合之后对甲醇的电催化性能明显提升, 并具有类铂电催化活性; 当钨与蒙脱石质量比为4 的前驱体经5 h 还原碳化后, 样品中WC占绝对主导, WC和W₂C的质量分数分别为82%和18%, 两者的比值为4.556, 且在MMT外表面形成均匀的负载层. 此时样品的电催化活性最高. 这为制备具有类铂催化活性的高性能碳化钨催化材料奠定了坚实基础.     

蔗渣纤维素黄原酸酯的制备及稳定性研究

以甘蔗渣为原材料,于20％(wt)的NaOH溶液中碱化24 h,在碱性条件下加入用量为0.5 mL/g的CS2,在30℃反应2.5 h,合成了蔗渣纤维素黄原酸酯(BCX)；并对其合成条件进行了优化,对其处理重金属离子的效果进行了评价.研究结果表明,BCX对重金属废水中的Ni2+、Cu2+、Zn2+、pb2+的去除率均在...     

稀土氨基酸水杨醛Schiff碱的合成及其生物活性

合成了水杨醛L-亮氨酸Schiff碱钇配合物{[Y2(Leu-Sal)3Cl4]Cl2.2H2O,Leu=L-亮氨酸,Sal=水杨醛},其结构经UV,IR,荧光光谱,元素分析,摩尔电导和差热-热重分析表征。生物活性实验表明,配合物对大肠杆菌、金黄色葡萄球菌和霉菌均有不同程度的抑菌作用。     

Electrodeposition of Catechol on Glassy Carbon Electrode and Its Electrocatalytic Activity Toward NADH Oxidation

Catechol can be oxidized electrochemically to its corresponding o‐benzoquinone. The electrogenerated quinone can be deposited by cycling the potential at the surface of glassy carbon electrodes. We have studied the electrochemical features of films derived from catechol by cyclic voltammetry. The electrodeposited film shows stable reversible redox response, dependent on pH as anticipated for quinone/catechol functionalities. Glassy carbon electrodes covered with a film derived from catechol exhibit catalytic activity in the electrooxidation of NADH at a low potential. The catalytic current is proportional to the concentration of NADH over the range 0.02–0.34 mM.     

Ethyl Xanthate and Propyl Xanthate as Activators and Inhibitors of Mushroom Tyrosinase in Different Concentrations

The effect of ethyl xanthate(I) and propyl xanthate(II) on the kinetics of hydroxylation by mushroom tyrosinase (MT) has been investigated at 20°C in 10 mM phosphate buffer solution, pH 6.8. 4‐[(4‐Methyl‐phenyl)azo]‐phenol (MePAPh) was used as a synthetic substrate for the enzyme for cresolase reaction. The results show that ethyl xanthate and propyl xanthate can activate or inhibit the cresolase activity of mushroom tyrosinase depending on the concentration of these effectors. Both I and II act uncompetitive at relatively high concentrations (20‐50 μM). The inhibition constant (K_i) values for I and II are 13.8 and 11 μM, respectively. However, both I and II act as activators at relatively low concentrations (0‐11.5 μM). Activation of the enzyme in low concentrations of xanthates arises from increasing the affinity of binding for the substrate as well as increasing the enzyme catalytic constant. The activation constant (K_a) values for I and II are 1.88 and 2.68 μM, respectively. The enzyme has two distinct sites for both effectors. The first one is a high‐affinity activation site and the other is a low‐affinity inhibition site.