卟啉-金属氧簇超分子化合物的光谱及电催化氧还原

应用紫外可见吸收光谱研究了meso 四(4 N 苄基吡啶基)卟啉(MTBPyP4＋,M=H2,Zn)阳离子与金属氧簇阴离子(SiW12O4－40)在水溶液中的光谱行为. 光谱演变及Job图表明MTBPyP4＋与SiW12O4－40在水溶液中可形成稳定的1∶1的超分子化合物. 同时本文还考察了化学计量为1∶1的[CoTBPyP][SiW12O40]超分子化合物的电催化分子氧还原行为, 表明该类超分子化合物有望成为一类新的催化氧还原的修饰电极材料.     

用三种不同方法研究TPPS4与DM-β-CD的相互作用

本文以极谱法、荧光光谱法和紫外可见光谱法研究了水溶性卟啉四-(4-磺基苯)卟啉(TPPS4)与2,6-二-氧-甲基--βCD(DM--βCD)的相互作用。结果表明,二者可发生反应,形成了TPPS4-DM--βCD的超分子体系。此外,本文还用极谱法和紫外-可见光谱法对TPPS4-DM--βCD超分子体系的包结比和包结常数进行测定,证明二者形成了1∶2的包结物;计算所得的包结常数为1.44×108L2.mol-2。     

用分子光谱法研究两种水溶性卟啉与磺丁醚-β-环糊精的超分子体系

本文以紫外可见光谱法和荧光光谱法研究了水溶性的四-(4-甲基吡啶基)卟啉(TMPyP)和四-(4-羧基苯基)卟啉(TCPP)与磺丁醚-β-环糊精(SBE--βCD)形成的超分子体系。结果表明,两种卟啉与磺丁醚-β-环糊精都形成了1∶1的包结物,它们的包结常数分别为1.34×104L.mol-1和1.15×105L.mol-1。     

meso-四(4-羧基苯基)卟啉及金属配合物的合成和对糖类的选择识别

用微波辐射和溶剂热方法合成了meso-四(4-羧基苯基)卟啉(TCPP)及其锌配合物,分别采用紫外-可见光谱滴定法和荧光光谱法测定了目标化合物对5种糖类化合物(D-葡萄糖、D-果糖、蔗糖、麦芽糖和乳糖)的分子识别作用.结果表明,两种卟啉化合物对麦芽糖有较好的识别作用,用紫外-可见光谱方法计算出TCPP和ZnTCPP与麦芽糖分别形成1∶2和1∶1的络合物,结合常数分别为8.1×107和8.1×103L·mol-1.     

基于金属氧簇和铜-四氮唑配合物构建的空旷骨架:合成、结构及性能

在水热条件下,通过CuCl2 6H2O、5-(2-吡啶基)-四唑与不同的金属氧簇阴离子反应,合成了3个基于金属氧簇与铜-四氮唑构建的空旷骨架:Cu4(2-ptz)4(H2O)7SiW12O40 4H2O(1),Cu5(2-ptz)6(OH)(H2O)3PW12O40 H2O(2),Cu9(μ-O)6(2-ptz)6(H2O)9(H6P2W18O62)3H2O(3)(2-ptz=5-(2-吡啶基)-四唑),并通过元素分析、红外光谱、热失重曲线、紫外-可见光谱、粉末衍射和单晶X射线衍射等手段进行了表征.结构分析表明:它们均为三维结构.化合物1是由分立的Z字形的Cu-(2-ptz)配合物单元与412 40SiW O-簇阴离子连接而成;化合物2是由二维的Cu-(2-ptz)网络与312 40PW O-簇单元桥连形成的;化合物3则是一个不常见的基于一维Cu-(2-ptz)链与62 18 62P W O-簇单元构建的.磁性研究结果表明:化合物1和2表现出反铁磁性,而化合物3表现出不常见的亚铁磁性.     

水溶性卟啉及其系列金属化合物的合成、抗癌活性及其作用机制研究

合成了水溶性四-[(4-三甲铵基)苯基]卟啉TAPP及其金属卟啉化合物MTAPP,其中M=Zn(),Cu(),Fe(),Co(),Ni(),Mn().通过元素分析、紫外-可见光谱确定了化合物的组成和结构.以紫外-可见光谱、荧光光谱及粘度法等手段研究了卟啉化合物TAPP和金属卟啉化合物ZnTAPP与小牛胸腺DNA的相互作用,结果表明,TAPP,ZnTAPP与DNA相互作用使紫外-可见光谱发生了8～12nm的红移,并出现了明显的减色效应.荧光光谱强度明显增大,吸收峰位发生变化.以艾氏腹水癌(Ac)和肝癌(Hept)细胞为靶细胞,采用MTT染色法评价了化合物的抗癌活性,部分化合物表现出较高的抗癌活性     

含多个氧化还原中心的卟啉化合物的电化学及光谱电化学行为(Ⅰ)

在DMF及DMSO中用循环伏安法、现场紫外可见光谱电化学方法及现场FT-IR光谱电化学方法研究了含多个氧化还原中心的卟啉化合物[四(对-硝基苯基)卟啉合钴(Ⅱ)]的氧化还原性质。指出该化合物的第一步氧化或第一步还原为中心金属钴失去或得到1个电子;第二步还原为卟啉环meso位的4个对硝基苯基上的硝基在同一电位下各得1个电子,形成相应的阴离子自由基;第三步还原为卟啉环得到1个电子,但该步反应不可逆。同时发现硝基与卟啉环及中心金属钴之间存在分子内电子相互作用,而4个硝基取代基之间未发现分子内电子相互作用。     

含多个氧化还原中心的卟啉化合物的电化学及光谱电化学行为(Ⅰ)

在DMF及DMSO中用循环伏安法、现场紫外可见光谱电化学方法及现场FT-IR光谱电化学方法研究了含多个氧化还原中心的卟啉化合物[四(对-硝基苯基)卟啉合钴(Ⅱ)]的氧化还原性质。指出该化合物的第一步氧化或第一步还原为中心金属钴失去或得到1个电子；第二步还原为卟啉环meso位的4个对硝基苯基上的硝基在同一电位下各得1个电子,形成相应的阴离子自由基；第三步还原为卟啉环得到1个电子,但该步反应不可逆。同时发现硝基与卟啉环及中心金属钴之间存在分子内电子相互作用,而4个硝基取代基之间未发现分子内电子相互作用。     

基于Keggin型金属氧簇与含氮有机配体自组装超分子化合物的晶体结构和电化学研究

通过水热方法合成了超分子化合物(H2bbi)2(SiW12O40).H2O.单晶X射线衍射分析表明化合物结晶于三斜晶系,P-1空间群.化合物中的两种亚单元通过氢键作用形成了超分子结构.此外,循环伏安法研究结果表明了化合物展示3个连续的双电子还原过程.     

L-苏氨酸铜(Ⅱ)超分子配合物的合成、晶体结构及性质

合成了L-苏氨酸铜(Ⅱ)超分子配合物[Cu(C4H8NO3)2].H2O,通过元素分析、红外、差热-热重、紫外光谱和单晶结构对其结构进行确认。该化合物由1个Cu(Ⅱ)离子、2个L-苏氨酸阴离子和1分子结晶水组成,其中氨基酸的羧基氧原子及氨基氮原子与铜(Ⅱ)离子配位,形成六配位拉长八面体构型,单胞之间通过分子间氢键构成三维网状超分子体系。配合物在水溶液中的紫外吸收波长为233nm,固态荧光发射之间通过分子间氢键构成三维网状超分子体系。配合物在水溶液中的紫外吸收波长为233nm,固态荧光发射出现在357nm。电化学行为显示,配合物在玻碳电极上为不可逆的氧化还原过程,反应过程受扩散控制。     

Synthesis, Crystal Structure and Photocatalytic Properties of a Supramolecular Assembly Based on Keggin Polyoxotungstate

A new supramolecular compound (4,4'-bipyH)4[SiW12O40](4,4'-bipy) (4,4'-bipy = 4,4'-bipyridine) was synthesized hydrothermally and characterized by single-crystal X-ray diffraction and IR spectrum. The crystallography analysis for the title compound reveals that the crystal crystallizes in monoclinic, space group C2/m with a = 22.2767(12), b = 21.1879(11), c = 15.6942(8) , β = 97.068(3)°, V = 7351.3(7) 3, C50H44N10O40SiW12, Mr = 3659.24, Z = 4, Dc = 3.306 g/cm3, F(000) = 6544, GOOF = 1.137, R = 0.0577 and wR = 0.1579. The title compound consists of a discrete Keggin-type [SiW12O40]4- anion, one 4,4'-bipy and four protonated (4,4'-bipyH)+ cations. The [SiW12O40]4- anion and protonated 4,4'-bipy are connected to form a supramolecular structure by hydrogen bonds. Meanwhile, the title compound exhibits good photocatalytic activity for color degradation of Rhodamine-B dye solution under visible-light irradiation.     

H_2O-DMSO体系中联吡啶甲基化及其钨硅酸盐的形成

以Keggin型钨硅酸H_4[SiW_(12)O_(40)]·24H_2O和MN~(2+)为原料,4,4′-联吡啶(4,4′-bipy)为有机前驱体,水和二甲基亚砜(DMSO)为混合溶剂,在水热条件下,4,4′-bipy发生N-甲基化,并与DMSO共同修饰[SiW_(12)O_(40)]~(4-)阴离子,形成了1个钨硅酸盐基无机-有机杂化化合物(CH_3)_2bipy)((CH_3)_2SOH)_2[SiW_(12)O_(40)].通过元素分析、红外光谱(IR)、热重(TG)及X-射线单晶衍射分析对该化合物进行了表征,初步探讨了该化合物的形成条件,并研究了其在水溶液中的电化学性质及其对H_2O_2还原的电催化活性.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11NiO6-39 and SiW11MnO6-39 on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11O39Ni(H2O)6-(SiNiW11) and SiW11O39Mn(H2O)6-(SiMnW11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-3 and NO-2 were comparatively studied.     

Keggin型缺位硅钨杂多阴离子的电化学性质及电催化还原H2O2

应用循环伏安、方波伏安和交流阻抗法研究了Keggin型缺位硅钨杂多阴离子SiW11O398-(SiW11)在0.1mol.L-1NaHSO4+Na2SO4溶液中的电化学性质及其对H2O2还原的间接电催化作用.结果表明,SiW11的酸性水溶液在玻碳(GC)电极上显示两对可逆的还原-氧化波,对应的电荷迁移数均为1,且有2个质子参与反应.根据第1对波的还原峰电流与扫描速率平方根关系得到SiW11在溶液中的扩散系数DO为8.92×10-6cm2.s-1.SiW11对H2O2的还原具有明显的电催化活性,催化峰电位随溶液pH的降低而正移,峰电流增大.质子H+在催化反应中起协同促进作用.实验测定该电催化过程的均相准一级反应速率常数为0.30 s-1.SiW11电催化还原H2O2的机理被认为是经过形成所谓"七配位过氧化物"而发生的.     

Incorporation of cationic electron donor of Ni-pyridyltetrathiafulvalene with anionic electron acceptor of polyoxometalate

A new salt-[Ni(II)(DMSO)(5)(TTFPy)](2)[α-SiW(12)O(40)] (1)-based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni(II). Although the TTFPy molecule did not form a salt with the anionic α-[SiW(VI)(12)O(40)](4-) because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW(VI)(12)O(40)](4-) was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW(VI)(12)O(40)](4-), forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW(VI)(12)O(40)](4-), which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW(VI)(12)O(40)](4-) by 0.317 V in methanol.     

Polynuclear complexes of main group and transition metals with polyaminopolycarboxylate and polyoxometalate

Six supramolecular compounds constructed by main group and transition metals, polyoxotungstates (SiW(12)O(40)(4-)) and trans-N,N,N',N'-1,2-cyclohexanediaminotetraacetic acid (H(4)CyDTA), (NH(4))(3)[Ni(4)Na(H(2)O)(10)(CyDTA)(2)][SiW(12)O(40)]·10H(2)O (1) (NH(4))(2)[Cu(3)Na(2)(HCyDTA)(2)(H(2)O)(13)][SiW(12)O(40)]·5H(2)O (2), (NH(4))(2)[Zn(5)(CyDTA)(2)(H(2)O)(16)][SiW(12)O(40)]·8H(2)O (3), (NH(4))(4)[Cd(4)(CyDTA)(2)(H(2)O)(8)][SiW(12)O(40)]·6H(2)O (4), (NH(4))(4)[Sr(3)(HCyDTA)(2)(H(2)O)(14)][SiW(12)O(40)]·2H(2)O (5) and [Ca(4)(H(2)CyDTA)(2)(H(2)O)(22)][SiW(12)O(40)]·8H(2)O (6), were synthesized in aqueous solution and characterized by IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction techniques. Single-crystal structure analyses indicate they are constructed by the complexes with different nuclearity and polyoxometalates. In the sequence of Ni, Cu, Zn the nuclearity of the homometallic complex units increases from 2 to 5. Cadmium ions gives a tetranuclear complex with a compact structure. In 5 and 6 the main group metal ions and CyDTA form polymeric chains. CyDTA exhibits rather different coordination patterns to main group metal ions and transition metal ions due to their ionic radii and electronic configuration. The complex units and polyoxometalates arrange in different patterns due to the different shapes of the complex units. The compounds exhibit different thermal decomposition processes and the formation of compounds 3 and 4 quenches ligand-centered emissions and gives a ligand-to-metal emission. The study on various temperature susceptibilities of 1 and 2 shows that there is an antiferromagnetic coupling in the two compounds but coupling patterns are different.     

Application of tetrazole-functionalized thioethers with different spacer lengths in the self-assembly of polyoxometalate-based hybrid compounds

Three metal-organic networks based on Keggin-type polyoxometalates (POMs) have been hydrothermally synthesized by tuning the spacer lengths of bis(tetrazole)-functionalized thioether ligands and structurally characterized: [Cu(4)(bmtm)(4)][SiW(12)O(40)]·2H(2)O (1), [Cu(4)(bmte)(3.5)][SiW(12)O(40)] (2), and [Cu(4)(bmtp)(4)][SiW(12)O(40)] (3) [bmtm = 1,1'-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)methane, bmte = 1,2-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)ethane, and bmtp = 1,5-bis(1-methyl-5-mercapto-1,2,3,4-tetrazole)pentane]. The spacer lengths and sulfhydryl of bis(tetrazole)-functionalized thioether ligands play important roles in the final framework formation, as shown by X-ray diffraction analysis. In compound 1, with the connection of a N,S bridge of bmtm, two kinds of binuclear Cu(I) units are formed and linked to construct a one-dimensional (1D) chain. The [SiW(12)O(40)](4-) (SiW(12)) cluster provides four terminal O atoms linking four binuclear units to generate a two-dimensional layer with (8(3))(2)(8(5)·10) topology. In compound 2, centrosymmetric octameric moieties composed of two equivalent tetrameric Cu(I) units are bridged by bmte ligands to form a 1D chain. The SiW(12) clusters show an unusual (2,8)-connected mode to connect with the 1D chain and construct a four-connected three-dimensional (3D) network with 5(3)·6(2)·7 topology. Compound 3 exhibits a rare 3D host framework with a type of large cavity and two types of small windows. The SiW(12) clusters as templates are strongly cemented into the large cavities and completely encircled by small windows. Furthermore, the compound 2 bulk-modified carbon-paste electrode (2-CPE) displays good electrocatalytic activity toward the reduction of nitrite.     

Polyoxometalate-stabilized Pt nanoparticles and their electrocatalytic activities

The synthesis of long-term stable polyoxometalate (POM)-stabilized Pt nanoparticles (NPs) is described here. By means of controlled bulk electrolysis, the reduced POM anions, SiW(12)O(40)(4-) (or SiW(12)) and H(2)W(12)O(40)(6-) (or H(2)W(12)), respectively, served the dual role of reductant and protecting/stabilizing ligand for the Pt NPs. Transmission electron microscopy (TEM) images confirmed the formation of 3 to 4 nm sized Pt NPs, which coincidently was in the same size range of the commercial Pt black that was used as a reference. Elemental XPS analyses showed W/Pt ratios of 0.12 for the SiW(12)- and 0.18 for the H(2)W(12)-stabilized Pt NPs, but found no evidence of the presence of Cl(-) anion in the samples. Controlled electrochemical (EC), UV-Vis, and IR data provided unambiguous evidence for the structural integrity of the POM anions on the Pt NP surface. CO stripping, methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR) were used to assess their electrocatalytic activities. It was found that both SiW(12)- and H(2)W(12)-stabilized Pt NPs showed enhanced activities in MOR and ORR as compared to that of Pt black, with the latter having higher enhancement. These observations clearly demonstrated that the stabilizing POM anions have a profound influence on the electrocatalytic activity of the underlying Pt NPs.     

New Inorganic-organic Hybrid Compound Containing One Dimensional Keggin Polyoxometalate[SiW11O39Co]6- Chains:Preparation,Characterization and Application in Chemically Bulk-modified Electrode

A new inorganic-organic hybrid compound based on polyoxometalate and organic ligand formulated as （H2bpp）3[SiWlIO39Co]-2H20（1）[bpp=l,3-bis（4-pyridyl）propane] was hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR, TG, and cyclic voltammetry. Single-crystal X-ray diffraction analysis reveals that compound 1 consists of interesting cobalt-monosubstituted POMs one dimensional chain together with protonated bpp ligands. Additionally, the polyoxoanions combined with the discrete organic substrates by hydrogen bond interactions to afford a supramolecular 3D network structure. The hybrid compound 1 was used as a bulk modifier to fabricate a three-dimensional chemically modified carbon paste electrode（1-CPE） by direct mixing. The electrochemical behavior and electrocatalysis of 1-CPE were studied in detail. The results indicate that 1-CPE has good electrocatalytic activities toward the reduction of nitrite or bromate in 1 mol/L 1-12SO4 aqueous solution. 1-CPE shows remarkable stability that can be ascribed to the insolubility of compound 1 and the supramolecular interactions existed between 1D POM anion chains and organic ligand bpp, which is very important for practical applications in electrode modification.