ChemInform Abstract: Gas Phase Water and Hydroxyl Binding Energies for Monopositive First-Row Transition-Metal Ions.

M+-OH2 and M+-OH binding energies of first-row transition metals are determined by means of collision-induced dissociation in a triple-quadrupole mass spectrometer.     

Thermal Studies on Solid Complexes of Uracil With Some Divalent Transition Metal Ions

The thermal behaviour of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pd(II) complexes of uracil was studied by TG, DTG and DTA in a dynamic nitrogen atmosphere. Two processes occur in the isolated uracil complexes: dehydration and pyrolytic decomposition. In the hydrated complexes, the first stage observed was the loss of water molecules, which was followed by decomposition of the uracil. The thermal dehydration of the complexes occurred in from one to three steps. The final decomposition products were found to be the respective metal oxides, except in the cases of the Co(II) and Pd(II) complexes, which produced metallic cobalt and palladium, respectively. The order of reaction and energy of activation for the dehydration stage were evaluated.This revised version was published online in November 2005 with corrections to the Cover Date.     

Solvation Numbers of Divalent Metal Salts and Ions in Some Non-aqueous Solvents

The few data available so far for the solvation numbers of divalent metal salts in non-aqueous solvents at infinite dilution are augmented by values in methanol, acetonitrile, N,N-dimethylformamide, and dimethylsulfoxide for alkaline earth and first row transition metal salts at 298.15 K. These were obtained from the isothermal compressibilities and the molar electrostriction volumes, as appropriate, with good agreement where comparable. Solvation numbers were evaluated for the individual ions, where possible. The intrinsic volume of the triflate anion was evaluated for this purpose.     

ChemInform Abstract: Theoretical ab initio SCF Study of Binding Energies and Ligand-Field Effects for the Hexahydrated Divalent Ions of the First-Row Transition Metals

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Complexation of Caffeic and Ferulic Acids by Transition-Metal Ions

Potentiometric titration and IR and UV spectroscopies are used to study complexation of caffeic and ferulic acids by metal ions. Caffeic and ferulic acids, which occur in lignin, are shown to react with metal ions mainly through an ionic mechanism. However, coordination bonding is also possible depending on the nature of the ligand and metal ion and the ratio of starting components. The strongest complex forms between caffeic acid and CuCl ₂ (2:1 ratio)     

Studies on Complexation of Resorcinol with Some Divalent Transition Metal Ions and Aliphatic Dicarboxylic Acids in Aqueous Media

The binary and ternary complexes of Cu²⁺, Ni²⁺, Co²⁺ and Zn²⁺ metal ions with resorcinol (R) as primary ligand and some biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids) as secondary ligands were studied in aqueous solution at 25 °C and I=0.1 mol⋅dm⁻³ NaNO₃ using the potentiometric technique. The formation of different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes is inferred from the corresponding potentiometric pH-titration curves. The ternary complex formation was found to take place in a stepwise manner. The protonation constants of the ligands were determined and used for determining the stability constants of the different complexes formed in aqueous solutions. The lower stability of the 1:2 binary complexes compared to the corresponding 1:1 systems of all ligands studied were in accordance with statistical considerations. The order of stability of the complexes formed in solution was investigated in terms of the nature of the resorcinol, carboxylic acid, and metal ion used. The values of Δlog ₁₀ K, percentage of relative stabilization (% R.S.), and log ₁₀ X for mixed-ligand complexes studied have been evaluated and discussed. The concentration distribution of the various species formed in solution was evaluated. The mode of chelation of the ternary complexes was ascertained by conductivity measurements.     

二价金属离子对磷脂聚集体的影响

通过浊度分析和激光光散射光谱研究了二价金属离子（Ca2＋、Cu2＋和Mn2＋）对蛋黄卵磷脂(EYPC)聚集态的影响.结果表明，自由的二价金属离子对EYPC囊泡有破坏作用,并使EYPC囊泡发生相转变,形成胶束;而与牛磺胆酸钠(TC)结合的二价金属离子使EYPC囊泡半径减小,但不破坏EYPC囊泡.     

过度金属对缺位Keggin结构杂多化合物的修复

合成了第四周期过渡金属取代的Keggin结构钼磷、钨磷杂多化合物．讨论了合成条件，运用P－0键的IR振动变化表征了过渡金属离子电子组态的变化对缺位配体的修复作用．     

Thermal Studies on Solid Complexes of Saccharin with Divalent Transition Metal Ions

The thermal decompositions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of saccharin were studied in static air atmosphere. All of the complexes contain four molecules of coordination water and two molecules of crystallization water. The water molecules were removed in a single stage, except from the Zn(II) complex, which exhibited two endothermic effects. The dehydration process was usually accompanied by a sharp colour change. The anhydrous complexes exhibited a phase transition and the decomposition or combustion of saccharin occurred in the second and subsequent stages. The final decomposition products were identified by XRPD as the respective metal oxides. The kinetic parameters, such as the order of reaction and energy of activation for the dehydration stage, were evaluated and the thermal stabilities of the complexes are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Electrochemical Deposition and Dissolution of Divalent Metal Ions

The deposition of Cu²⁺ and Zn²⁺ from aqueous solution has been investigated by a combination of classical molecular dynamics, density functional theory, and a theory developed by the authors. For both cases, the reaction proceeds through two one‐electron steps. The monovalent ions can get close to the electrode surface without losing hydration energy, while the divalent ions, which have a stronger solvation sheath, cannot. The 4s orbital of Cu interacts strongly with the sp band and more weakly with the d band of the copper surface, while the Zn 4s orbital couples only to the sp band of Zn. At the equilibrium potential for the overall reaction, the energy of the intermediate Cu⁺ ion is only a little higher than that of the divalent ion, so that the first electron transfer can occur in an outer‐sphere mode. In contrast, the energy of the Zn⁺ ion lies too high for a simple outer‐sphere reaction to be favorable; in accord with experimental data this suggests that this step is affected by anions.     

Separation of Selected Transition Metal Ions and Divalent Metal Ions by HPLC Using UV-VIS Detection

Abstract

The use of ethylenediaminetetraacetic acid, disodium salt, (pH 3-5) has been investigated as an eluant for the separation and detection of nanogram levels of selected divalent and trivalent metal ions. The effect of pH and eluant concentration upon the retention times and resolution of the system are given and the ability to alter the eluant characteristics to optimize the chromatographic results in different situations will be discussed. The method is less complicated than the method frequently used for transition metal ion determinations which uses a post-column derivitization reagent. This method is applicable to a wider range of metal ions and provides detection limits which are generally within two orders of magnitude of the post-column derivitization method.     

Protonation Equilibria of Carminic Acid and Stability Constants of Its Complexes with Some Divalent Metal Ions in Aqueous Solution

The dissociation constants of carminic acid (7-D-glucopyronosyl-3,5,6,8-tetra- hydroxy-1-methyl-9,10-dioxo-anthracene-2-carboxylic acid) (CA), together with the stability constants of its Cu(II), Zn(II), Ni(II), Co(II) and Hg(II) complexes, were studied potentiometrically in aqueous medium at 25.0?(1)?°C, and at the ionic background of 0.1?mol?dm^?3 of NaCl, and determined with the SUPERQUAD computer program. It has been observed that carminic acid has five dissociation constants, and for H₅L their values are 3.39?(7), 5.78?(7), 8.35?(7), 10.27?(7), and 11.51?(7). This ligand behaves as a bi-dentate ligand, and the carboxyl and the ortho hydroxy groups of the ligand coordinate to the metal ions. Various metal complexes were produced in solution under the experimental conditions, for each metal ion used, including hydrolyzed species. The species distribution curves of the complexes formed in the solution were calculated and reviewed. The stability of the complexes was found to follow the order: Cu(II) > Zn(II) > Ni(II) > Co(II) > Hg(II).     

二价金属离子对含铜水滑石结构稳定性的影响

通过构建不同的二价金属离子(M²⁺=Mg²⁺, Ca²⁺, Zn²⁺, Cd²⁺, Ni²⁺, Co²⁺)部分取代铜离子形成CuM₂Al 水滑石(CuM₂Al-LDHs)的周期性模型, 基于密度泛函理论(DFT), 用CASTEP程序模块对周期性模型进行几何全优化和性质计算, 通过分析各体系的结构参数、电子排布、Mulliken 电荷布居、氢键、结合能, 总结出含铜水滑石体系结构的稳定性规律. 计算结果表明: 在CuM₂Al-LDHs 体系中, 主客体间作用力对层板厚度的影响占主要因素; M离子对中心三价铝离子的影响较小, 对二价铜离子的影响较大, 其中价电子均匀排布的M离子对铜的畸变影响小于价电子不均匀排布的M离子. 另外在价电子均匀排布的CuM₂Al-LDHs 体系中, 主客体间的静电作用力和氢键强度逐渐增强. 总体上, 随着M离子周期数的增加, 体系的畸变角增大, 结合能绝对值逐渐减小, 体系的稳定性下降. 价电子不均匀排布的CuCo₂Al-LDHs 体系的稳定性最差. 这有助于从理论上更好地认识含铜水滑石的合成规律.     

稀土-过渡金属桥联异四核配合物的磁性及电化学研究

合成了两种不对称草酰胺桥联异四核配合物[Cu(oxca)]3M(H2O)2·5H2O[oxca表示N (2 羧基苯)·N′ (3 氨丙基)草酰胺三价阴离子,M=Nd(Ⅲ),Gd(Ⅲ)]。用元素分析、红外光谱、电子光谱等对所合成配合物进行了表征。在DMSO中采用循环伏安法研究了配合物的电化学性质。在4～300K范围内测量了[Cu(oxca)]3Gd(H2O)2·5H2O体系的变温磁化率,经拟合得磁参数J=0.537cm-1。结果表明异四核配合物分子内金属离子间存在较弱的铁磁性自旋交换相互作用。     

二价金属离子对鲑鱼精DNA热稳定性的影响

二价金属离子与 DNA之间的作用在 DNA复制、转录以及新陈代谢过程中起到重要的作用 ,因此越来越受到关注 [1,2 ] .L uck等 [3 ]指出 ,碱土金属与 DNA分子的磷酸基团发生作用使 DNA的热稳定性升高 ,而二价过渡金属离子主要是与碱基作用而使 DNA热稳定性降低 . Eichhorn等 [4 ] 用变温紫外光谱法研究了在 DNA磷酸根离子的浓度较小 (0～ 4.0 )时 ,多种二价金属离子对小牛胸腺 DNA热稳定性的影响 ,发现 Mg2 + 及过渡金属离子 Mn2 + ,Co2 + 和 Ni2 + 都有利于 DNA的稳定 .最近 ,Duguid等 [5]用差示扫描量热法 (DSC)研究了在 c(M2 +…     

Complexation and Thermal Studies of Uric Acid with Some Divalent and Trivalent Metal Ions of Biological Interest in the Solid State

Nine new [metal uric acid] complexes [M(Ua) n ]°·XH 2 O have been synthesized. These complexes have been characterized by elemental analysis, X-ray diffraction (XRD), magnetic susceptibility ( w eff. ), FTIR spectra, thermal analysis (TG & DTA), and electronic spectra (UV/visible). Uric acid (HUa) coordinates as a bidentate ligand to Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Al(III), Cr(III) and Fe(III) through the protonated N-7 within the imidazole ring and O-6 within the pyrimidine ring. Uric acid forms neutral metal urate complexes with all the above metal ions. The quantitative compositions were determined as [M(Ua) 2 ·(H 2 O) 2 ]°·XH 2 O where M(II)=Mn, Fe, Co, Ni, Cu, Zn and X=2, 4, 2, 4, 2, 2, respectively. The M(II) complexes exhibit an isostructural octahedral coordination with N-7, O-6 of two uric acid ligand molecules, and O of two water molecules. Compositions were also determined as [M(Ua) 3 ]°·YH 2 O where M(III)=Al, Cr, Fe and Y=6, 3, 3 respectively. All the M(III) complexes form an isostructural octahedral coordination with N-7 and O-6 of three uric acid ligand molecules. Iron(III) complexes prepared with N 1 , N 3 and N 9 -methyl uric acid yielded brown complexes with a metal ligand ratio of 1 3, while N 7 -methyl uric acid did not yield a complex due to blockage of N-7 with a methyl group.     

荧光光谱法研究卟啉与金属离子配位反应机理初探

本文用荧光光谱法初步研究了卟啉与金属离子配位反应机理和部分催化剂的催化机理.实验发现,在一定条件下,卟啉以一种与其主要存在形式不同的变形体H₂P^*存在,根据H₂P^*的存在和产生的条件,对卟啉与金属离子配位反应的一般条件作出了较为满意的阐述.     

Adsorption Mechanism of Composite Whisker on Copper Ions and Lead Ions

A new kind of inorganic composite adsorbent based on chitin whiskers(CHW) and potassium tetratitanate whiskers(PTW) was synthesized via the thermal deposition to remove Cu²⁺ and Pb²⁺ from wastewater. CHW could be successfully coated on the surface of PTW when thermal treated 8 times. The adsorption process was better fitted with the Langmuir and Freundlich models. The adsorption process was more conformed to the Pseudo-second-order model. The results from XPS(X-ray photoelectron spectrum) further show that the adsorption mechanism between CHW-PTW and Cu²⁺, Pb²⁺ are both ion exchange and chemical adsorption. Thermodynamic parameters suggest that the adsorption processes are nonspontaneous. The adsorption of Cu²⁺ and Pb²⁺ is endothermic and exothermic, respectively.     

Interaction of Clofazimine with Divalent Metal Ions: A Fluorescence Quenching Study

The interaction of clofazimine (CFZ) with divalent metal cations was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultraviolet spectra. The fluorescence quenching spectra of CFZ in the presence of metal ions showed that metal ions quenched the fluorescence of CFZ. The quenching constants were determined using the Stern–Volmer equation. The binding constants (log K) and binding site were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between CFZ and metal ions was mainly driven by a hydrophobic force. The conformational changes of CFZ were investigated by synchronous spectrum studies.