烟酸和1,10-邻菲啰啉构建的Cu(Ⅱ)配合物与DNA的相互作用

采用光谱法、循环伏安法和热变性方法,研究了烟酸(NA)和1,10-邻菲啰啉(Phen)构建的三元Cu(Ⅱ)配合物([Cu(Phen)(NA)]·H2O)与鲱鱼精DNA的相互作用。结果显示:NA中羧酸根离子与Phen中两个氮原子均与Cu(Ⅱ)双齿配位,形成的配合物在0.141~0.205V出现一对灵敏的氧化还原峰,并且配合物在玻碳电极上的反应主要由扩散过程控制。加入DNA后配合物的最大吸收峰发生了明显红移和减色,且配合物的氧化还原峰电流显著降低,式量电位发生正移;配合物能猝灭中性红(NR)-DNA体系的荧光,同时配合物的加入使DNA熔点升高,表明配合物与DNA存在嵌入结合。     

两种甲氧基苯基咔咯铜配合物的合成及光谱性质

合成了两个中位苯基上具有甲氧基取代基的铜咔咯配合物(Tp-OCH3PC)Cu和(To,p-(OCH3)2PC)Cu,通过紫外-可见、红外光谱、元素分析、核磁共振及质谱对它们进行了表征。研究了配合物在非水溶剂中的电子顺磁共振、电化学和光谱电化学性质,结果表明无论在固体状态还是在非水溶剂中,配合物的中心金属离子均为三价铜Cu(Ⅲ),在给定的溶剂中Cu(Ⅲ)可以发生可逆的还原反应生成Cu(Ⅱ),也可以被可逆氧化为Cu(Ⅲ)的阳离子自由基。探讨了甲氧基取代基以及溶剂对配合物的紫外-可见光谱和氧化还原电位的影响。     

席夫碱Cu(Ⅱ)配合物与鲱鱼精DNA的相互作用研究

采用电化学和光谱法,研究了糠醛缩对氨基苯磺酸席夫碱Cu(Ⅱ)配合物与鲱鱼精DNA的相互作用。结果发现:糠醛缩对氨基苯磺酸席夫碱Cu(Ⅱ)中加入DNA后,氧化还原峰电流降低,式量电位正移;席夫碱Cu(Ⅱ)配合物使DNA的最大吸收峰强度增强,DNA使席夫碱Cu(Ⅱ)配合物的荧光强度增强。表明席夫碱Cu(Ⅱ)配合物以嵌插模式与DNA作用。     

1-羟基-2-乙酰基呫吨酮类希夫碱双核配合物的研究 Ⅰ Cu(Ⅱ)配合物的合成和表征

以1-羟基-2-乙酰基咕吨酮和肼基二硫代甲酸甲酯缩合所得希夫碱(以H_2L表示),与Cu(Ⅱ)反应制得三种双核配合物。通过元素分析、红外、紫外-可见,磁化率、电子顺磁共振和循环伏安法等对配合物进行了表征和研究.表明这些配合物中,在所处化学环境不同的两个Cu(Ⅱ)之间存在较弱的自旋交换作用。桥联配体为醋酸根时,表现出不可逆的氧化还原性质,其余配合物显示准可逆的双电子转移过程.在吡啶存在时,醋酸根配位的双核铜配合物的氧化还原可逆性增加,其余配合物表现出可逆的两步单电子转移过程,同时还原电位正向移动.     

光催化反应过程中铜的价态分析Cu(Ⅰ)-新铜试剂-Triton X-100体系

新铜试剂(2,9-二甲基-1,10非罗啉)可分别与Cu(Ⅰ)与Cu(Ⅱ)生成配合物,Cu(Ⅱ)配合物在光照射下产生光还原作用,而生成Cu(Ⅰ)配合物,在pH3.0～4.0范围内,光还原作用基本不发生。在Triton X-100存在下,可在水溶液中直接测定光催化反应过程中Cu(Ⅰ)与Cu(Ⅱ),结果令人满意。     

伏安法研究五元瓜环对Cu(Ⅱ)配合物的识别性能

利用伏安法研究了五元瓜环(记为Q[5])对Cu(Ⅱ)配合物的识别性能。结果表明:在pH 5.0的Na2(H2EDTA)介质中,扫描速度为100 mV.s-1时,Q[5]-[Cu(H2EDTA)H2O]配合物的电极反应为单电子准可逆氧化还原反应。摩尔比法测出Q[5]与[Cu(H2EDTA)H2O]作用比为2∶1,稳定常数为3.59×109 L2.mol-2。在所选择的实验条件下,Cu(Ⅱ)浓度在2×10-6~1.6×10-4 mol.L-1范围内,峰电流与其浓度具有较好的线性关系,方法回收率为99.4%~100.7%。     

邻菲咯啉-铜(Ⅱ)-L-亮氨酸配合物与DNA的结合

应用循环伏安法、微分脉冲伏安法、电子吸收光谱和溴化乙锭(EB)荧光分析法研究了[Cu(phen)(H2O)(L-Leu)^ ](phen=1，10-邻菲咯啉，L-Leu=L-亮氨酸)与小牛胸腺DNA的相互作用。结果发现中心铜离子在循环伏安图上呈现一对明显的准可逆氧化还原波。当加入一定量的DNA时，配合物的氧化还原峰电流明显降低，配位阳离子的扩散系数减小，电子光谱的最大吸收峰明显红移，产生明显的减色效应。同时，配合物也能较大程度地猝灭EB-DNA体系的荧光，证明配合物与DNA存在插入结合。     

铜(Ⅱ)邻菲咯啉蛋氨酸配合物与DNA相互作用的研究

在pH=6．86磷酸盐缓冲溶液中，采用电化学(循环伏安法、微分脉冲伏安法和 交流阻抗及数据拟合技术)、粘度测定、电子吸收光谱和溴化乙锭(EB)荧光分析法 研究了[Cu(phen)(H2O)(L—Met)]^+(phen＝1，10-邻菲咯琳，L—Met=L-蛋氨酸)与 小牛胸腺DNA的相互作用。结果发现中心铜离子在循环伏安图上呈现1对明显的准可 逆氧化还原波。当加入一定量的DNA时，配合物的氧化还原峰电流明显降低，扩散 系数减小，电化学反应电阻增大，电子光谱的最大吸收峰明显红移，产生明显的减 色效应，同时，配合物也能较大程度地猝灭EB-DNA体系的荧光，说明[Cu(phen) (H2O)(L—Met)]^+与DNA的作用较强，作用模式为部分插入作用。     

铜(Ⅱ)与芳基取代酰基吡唑啉酮、腺嘌呤三元配合物吸附波的研究

在Hac-NaAc缓冲溶液中(pH 5.0),用单扫示波极谱法得到1-对氯苯基-3-呋喃基-4-呋喃甲酰基-5-吡唑啉酮(HL)、腺嘌呤(Ade)与铜(Ⅱ)三元配合物的灵敏吸附波,其峰电位为-0.58 V(vs.SEC).峰电流与铜质量浓度在0.02～10mg/L范围内分段呈线性关系,定量下限为2μg/L(3×10-8mol/L).采用多种电化学方法研究了极谱波的性质和电极反应机理.峰电流由中心离子铜(Ⅱ)还原产生.用直线法测得多元配合物组成比为1:1:1,表观稳定常数为7×107.此方法已用于粗盐、麦片和化妆品中痕量铜的测定,标准回收率98%～103%.     

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 and Crystal Structure of a New Copper(Ⅱ) Complex with 4-Cyanobenzoic Acid

A new Cu(Ⅱ) complex [Cu(4-cba)(l,10-phen)(H2O)2](NO3) (4-Hcba = 4-cyanobenzoic acid) has been synthesized by solvothermal reaction in an ethanol/water mixed solution at 100℃ and structurally characterized by single-crystal X-ray diffraction. Crystallographic data: C20H16CuN4O7, Mr= 487.91, triclinic, space group P1, a = 7.8420(2), b = 9.1070(2), c = 15.1140(6) A,α=76.889(9), β = 81.332( 11 ), γ = 74.844(11 )°, V = 1009.89(5) A3, Z = 2, Dc = 1.605 g/cm3, F(000)=498,μ=1.134 mm-1,the final R = 0.0379 and wR = 0.0865 for 2977 observed reflections with I ＞ 2σ(Ⅰ).The Cu(Ⅱ) atom is coordinated by two terminal water molecules, one chelating 1,10-phen molecule and one monodentate 4-cba ligand to form a slightly distorted square pyramid. The title complex molecules are connected through hydrogen bonds and π-π stacking interactions to generate a 2D layered network. The thermogravimetric analysis of the title complex has also been discussed.     

Electrochemistry of catechol terminated monolayers with Cu(II), Ni(II) and Fe(III) cations: a model for the marine adhesive interface

The redox electrochemistry of hydroquinone and Cu2+-, Ni2+-, and Fe3+-hydroquinone complexes immobilized at the SAM interface has been studied in aqueous solutions with pH 5 to 12 using cyclic voltammetry. Self-assembled monolayers were constructed with terminal hydroquinone residues designed to model marine adhesive proteins that use the DOPA (3,4-dihydroxyphenylalanine) moiety. Coordination of metal to the hydroquinone group results in a shift to the ligand oxidation potential, with the value for Delta E p,a dependent on the solution pH and identity of the metal. Cu2+ shifts the hydroquinone oxidation by -285 mV (pH 8.8), and Ni2+ by -194 mV (pH 9.16). The hydroquinone oxidation was shifted by -440 mV at pH 5 for Fe3+ solutions examined up to pH 7. By contrast, reduction of the quinone is unperturbed by the presence of Cu2+, Ni2+, and Fe3+ ions. Implications of these results to the mechanism of marine adhesion are discussed.     

Two copper(II) complexes with 4-benzoylpyridine ligand: synthesis, crystal structure and luminescent properties

Two new copper(II) complexes Cu(NCS)2(4-Bzpy)2 (1) and Cu(NO3)2(4-Bzpy)4 (2) (4-Bzpy=4-benzoylpyridine) have been synthesized and characterized by IR, UV, elemental analysis and X-ray crystallography. Cu(II) atom has a square planar environment for 1 and an distorted octahedral environment for 2, respectively. In solid state there are C-H?π interactions and C-H?S hydrogen bonds between adjacent molecules in complex 1. The molecule of complex 2 is further connected by multiform π-π interactions, C-H?π interactions and C-H?O hydrogen bonds to form a three-dimensional supramolecular structure. The luminescent properties of the complexes 1 and 2 were both investigated in H2O solution and in solid state at room temperature, respectively.     

一个铜(Ⅱ)镍(Ⅱ)超分子化合物的合成、晶体结构与磁性

one new complex, [Cu(aeop)Ni(dpt)(H₂O)]·5H₂O, [H₄aeop=N′-(2-Aminoterephthalic acid)-N″-(1,3-Pro-panediamine) Oxamide], has been prepared by the diffusion method, where (aeop)^4- as bridging ligand, dpt as end ligand and characterized by elemental analysis, IR and X-ray crystal structure determination. It crystallizes in the Triclinic system, P1 space group with a=0.885 92(4)nm, b=1.232 53(6)nm, c=1.301 24(6)nm, α=85.593 0(10)°, β=78.753 0(10)°, γ=89.382 0(10)°, V=1.389 43(11) nm³, Z=2. The crystal structure analysis shows that intermolecular O-H…O and N-H…O hydrogen bonds result in a 3D supermolecular construction. The complex was characterized by magnetic susceptibility and presents a antiferromagnetic interaction (J=-46.4 cm^-1, g=2.24). CCDC: 727559.     

Synthesis,Crystal Structure and Ferromagnetic Properties of a New Dicyanamide Bridged Dicopper(Ⅱ) Complex with IM-1′-MeBzIm-κ2 N,O Mode

A new dinuclear copper(Ⅱ) complex with imino nitroxide radicals [Cu2(NO3)2(IM-1′-MeBzIm)2(dca)2] (IM-1′-MeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimi-dazoline-1-oxyl, dca = dicyanamide anion) has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P1, with a = 9.440(5), b = 10.124(6), c = 11.603(7), α = 102.904(7), β = 94.033(6), γ = 104.299(7)°, C34H40Cu2N16O8, Mr = 927.90, V = 1038.2(10) 3, Z = 1, Dc = 1.484 g/cm3, μ(MoKα) = 1.093 mm-1, F(000) = 478, R = 0.0609 and wR = 0.1512 for 2889 observed reflections with I > 2σ(I). X-ray analysis reveals that two Cu(Ⅱ) atoms are bridged by two dicyanamides to form a centrosymmetric Cu(Ⅱ)-Cu(Ⅱ) dinuclear entity. Every Cu(Ⅱ) ion is five-coordinated with a distorted square pyramidal coordination geometry and IM-1′-MeBzIm ligand coordinates to the metal ion with the κ2 N(1′-MeBzIm), O(IM) mode to avoid steric hindrance with the methyl group in the complex. Meanwhile, the molecules are linked by intermolecular hydrogen bonds, leading to a 1-D chain structure. Moreover, such chains are further linked by π-π stacking interactions to form a 2-D network structure. Magnetic measurement demonstrates that the intramolecular exchange couplings between Cu(Ⅱ) ion and the IM-1′-MeBzIm are ferromagnetic with J = 12.46 cm-1, where the spin Hamitonian is defined as■ = -2J12 within the complex.     

Rare example of mu-nitrito-1kappa2O,O':2kappaO coordinating mode in copper(II) nitrite complexes with monoanionic tridentate Schiff base ligands: structure, magnetic, and electrochemical properties

Three new copper(II) complexes, [CuL(1)(NO(2))](n) (1), [CuL(2)(NO(2))] (2), and [CuL(3)(NO(2))] (3), with three similar tridentate Schiff base ligands [HL(1) = 6-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one, HL(2) = 6-amino-3-methyl-1-phenyl-4-azahex-2-en-1-one, and HL(3) = 6-diethylamino-3-methyl-1-phenyl-4-azahex-2-en-1-one] have been synthesized and characterized structurally and magnetically. In all three complexes, the tridentate Schiff base ligand and one oxygen atom of the nitrite ion constitute the equatorial plane around Cu(II), whereas the second oxygen atom of the nitrite ligand coordinates to one of the axial positions. In 1, this axially coordinated oxygen atom of the nitrite ligand also coordinates weakly to the other axial position of a Cu(II) ion of another unit to form a one-dimensional chain with the mu-nitrito-1kappa(2)O,O':2kappaO bridging mode. Complexes 2 and 3 are discrete monomers that are joined together by intermolecular H bonds and C-H....pi interactions in 2 and by only C-H....pi interactions in 3. A weak antiferromagnetism (J = -1.96(2) cm(-1)) is observed in complex 1 due to its asymmetric nitrite bridging. Complexes 2 and 3 show very weak antiferromagnetic interactions (J = -0.089 and -0.096 cm(-1), respectively) attributed to the presence of intermolecular H-bonding and C-H....pi interactions. The corresponding Cu(I) species produced by the electrochemical reduction of complexes 1 and 2 disproportionate to Cu(0) and Cu(2+,) whereas the reduced Cu(I) species of complex 3 seems to be stable presumably due to a higher tetrahedral distortion of the equatorial plane in 3 compared to that in 1 and 2.     

Synthesis and Crystal Structure of a Hydrogen-bonded Supramolecular Compound [(C_6H_5N_2O)_3·Cu_1._5]·6H_2O

1 INTRODUCTION The binding of metal ions by proteins and pep- tides is of fundamental interest due to the impor- tance of metal ions in biological systems. Metals may be part of the active sites of enzymes, stabilize the macromolecular structure of proteins and affect enzymes or membranes to control cell metabolism[1]. Therefore, for many years there has been a great in- terest in the study of complexes able to mimic these active sites of metalloproteins. In this case, metal complexes of…     

Studies of nitric oxide interaction with mono- and dinuclear copper(II) complexes of prion protein bis-octarepeat fragments

The interaction of nitric oxide with copper(ii) complexes of two octarepeat sequences belonging to the prion protein was studied, considering both mononuclear and dinuclear systems, i.e. Cu-Ac-(PHGGGWGQ)(2)-NH(2) and Cu(2)-Ac-(PHGGGWGQ)(2)-NH(2), respectively. The NO interaction with both systems was followed in aqueous solutions at physiological pH value, by using UV-Vis and EPR spectroscopic techniques as well as cyclic voltammetry. The mechanism of NO interaction with the mononuclear copper complex can be considered similar to that previously observed for the analogous copper systems with Ac-HGGG-NH(2) and Ac-PHGGGWGQ-NH(2). A more complicated behaviour was found with the copper dinuclear system, in which the involvement of two different intermediate complex species was evidenced. A positive cooperativity between the two copper ions, in the reduction process was inferred. When working with a large excess of the Ac-(PHGGGWGQ)(2)-NH(2) ligand, the frozen-solution EPR parameters pertain to the well characterized [Cu(N(im))(4)](2+) unit, which did not exhibit any interaction with NO. The presence of a free coordination site is the necessary requirement for the NO interaction to occur, as found only in the square-pyramidal geometry of [Cu(L)H(-2)] or [Cu(2)(L)H(-4)] complex species, which form when copper and ligand concentrations are similar.     

Determination of nickel by anodic adsorptive stripping voltammetry with a cation exchanger-modified carbon paste electrode

The behavior of a modified carbon paste electrode (CPE) for nickel determination by anodic adsorptive stripping voltammetry (AAdsSV) was studied. The electrode was built incorporating the Dowex 50W x 12 (H(+) form) ion exchanger to a Nujol-graphite base paste. Ni(2+) was preconcentrated on the electrode surface in open circuit conditions, with the reduction (-1300 mV)/reoxidation step carried out in HCl solution (pH 3). During deposition time (5 min), the hydrogen evolution did not present obstacle in the quantification of nickel. For 12 min of accumulation and 5 min of deposition, nickel can be quantified up to 600 mug l(-1). The detection limit was 0.005 mug l(-1) at a linear potential scan rate of 200 mV s(-1). Interferences from Hg(2+) and Ag(2+) up to a concentration of 1 and 0.6 mg l(-1), respectively, were eliminated with the aid of the anion exchanger Dowex-2 (mesh 200-400) which was added to the sample in the preconcentration step. The tolerance for some metal ions such as Cu(2+), Cd(2+), Fe(3+), Zn(2+), Co(2+) and Pb(2+) was improved in the same way. The method was applied for the determination of nickel in samples of tap and mineral water. At the concentration level of 50 mug l(-1) of Ni (2+), the results were in good agreement with those obtained using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). For a Ni(2+) concentration of 5 mug l(-1), the results obtained showed better accuracy than those obtained by ICP-AES.     

Electrocatalytic Nitrite Reduction to Nitrogen Oxide by a Synthetic Analogue of the Active Site of Cu‐Containing Nitrite Reductase Incorporated in Nafion Film

The electrocatalytic reduction of nitrite to NO by [CuMe₂bpa(H₂O)(ClO₄)]⁺ ( 1 ), which is a model for the active site of copper‐containing nitrite reductase, incorporated in Nafion film was investigated. The Cu complex in the Nafion matrix exhibits an intense band at 267 nm and a broad band around 680 nm, assigned to d–d and ligand field transitions, respectively. The 77‐K EPR spectrum of 1 in the Nafion matrix reveals the typical axial signals (g_//=2.28, g =2.08, A_//=13.3 mT) of a tetragonal Cu²⁺ chromophore. The redox potential, which is related to the Cu⁺/Cu²⁺ couple, was ?146 mV (ΔE=72 mV) at pH 5.5. The redox reaction of 1 in Nafion was not dependent on pH and was a diffusion‐controlled process. The electronic structure and redox properties of 1 in the negatively charged polymer matrix were almost the same as those in aqueous solution. In the presence of nitrite, an increase in the cathodic current was observed in the cyclic voltammogram of 1 in the Nafion matrix. The current increase was dependent on the nitrite concentration and pH in solution. Upon reaching ?400 mV, a linear generation of NO was observed for the 1 /Nafion film coated electrode. The relationship between the rate of NO generation and the nitrite concentration in solution was analyzed with the Michaelis–Menten equation, where V_max=45.1 nM s^?1 and K_m=15.8 mM at pH 5.5. The Cu complex serves the function of both the catalyst and electron transport in the Nafion matrix. The sensitivity of the electrode was estimated to be 3.23 μA mM^?1 in the range of 0.1–0.4 mM nitrite.