Mechanism of ascorbic acid oxidation by molecular oxygen in aqueous pyridine catalyzed by CO2+, Ni2+, Mn2+ and Zn2+

Data on the radical non-chain mechanism of ascorbic acid oxidation by molecular oxygen catalyzed by Co²⁺, Ni²⁺, Mn²⁺ and Zn²⁺ ions are reported.

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Co²⁺, Ni²⁺, Mn²⁺ Zn²⁺.

     

Competitive uptake of Cs+, Ba2+, and Zn2+ ions from binary aqueous mixtures by zeolite-13X

The preferential exchange uptake of the cations Cs⁺, Ba²⁺ and Zn²⁺ from pure solutions by zeolite-13X follows the order Q [Cs⁺]>Q [Ba²⁺]>Q [Zn²⁺], while in case of binary mixtures the order is Q [Ba²⁺(Zn²⁺)]>Q [Ba²⁺(Cs⁺)]>Q [Cs⁺(Zn²⁺)]>Q [Cs⁺(Ba²⁺)]>Q [Zn²⁺(Cs⁺)]>Q [Zn²⁺(Ba²⁺)]. Ba²⁺ uptake from mixtures shows the least suppression effect.

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Cs⁺, Ba⁺² Zn⁺² -13 Q[Cs⁺]>Q[Ba⁺²]>Q[Zn⁺²] Q[Ba⁺²(mix Zn⁺²)]>Q[Ba⁺²(mix Cs⁺)]>Q[Cs⁺(mix Zn⁺²)]>Q[Cs⁺(mix Ba⁺²)]>Q[Zn⁺²(mix Cs⁺)]>Q[Zn⁺²(mix Ba⁺²)]. Ba⁺² .

     

Microwave-optical double resonance in molecular ions. Co+

Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for ¹²C¹⁶O⁺. With the optical excitation of fluorescence from the R₁ ($\text{1}\text{2}$) line of the (0,0) band of the A²Π_{$\text{3}\text{2}$} ← X²∑ transition of 20350.6 cm^?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = $\text{3}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ and the N = 1, J = $\text{1}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ transitions.     

Multiple scattering method applied to the electronic structure and spectra of the impurity ions Cu2+, Ni2+, Co2+, Fe2+ and their tetrahedral environments in ZnO,ZnS and CdS

The multiple scattering method with local exchange and muffin-tin potentials is applied to tetrahedral clusters with Cu²⁺, Ni²⁺, Co²⁺ and Fe²⁺ as central ions and oxygen and sulphur as ligands. The calculated orbital energy differences ?(t₂^*) - ?(e^*) are compared to Δ_t values deduced from optical spectra. The agreement is fairly good.     

Potentiometrische Bestimmung von Silber mit KJ in Gegenwart von Fe3+, Zn2+, Pb+, Cu2+ und Ni2+

Ohne Zusammenfassung     

中位-四(对烷氧苯基 )卟啉 Co2+、Cu2+、Zn2+、Pb2+配合物的合成与表征

Synthesis of fourteen new complexes of meso-tetrakis(4-alkoxyphenyl) porphyrins with Co²⁺, Cu²⁺, Zn²⁺, Pb²⁺ were presented in this paper.Meso-tetrakis (4-alkoxyphenyl) porphyrins were prepared by condensation of 4-alkoxybenzaldehydes with pyrrole, then treated with corresponding metallic acetate to produce mentioned complexes, IR, UV, ¹H NMR, MS and elementary analysis were explored to confirm the structures of all theses new complexes.Characteristic spectrometric data of IR, UV, ¹H NMR related to these complexes have been systematically summarized.Ten of the fourteen complexes were found to exhibit liquid crystal properties.     

在Y型分子筛中Co2+、Ni2+配合物的合成及其应用研究

用气相法和液相法分别在Y型分子筛的超笼中合成了Co²⁺、Ni²⁺的乙二胺配合物,并用红外(FT-IR)、顺磁共振(ESR)等方法对配合物的组成和稳定性进行了研究。CO²⁺的单核配合物在室温下可与O₂分子形成加合物,这种优先并可逆地吸附氧气的性能在氧气富集、对空气进行氧氮分离和食品保鲜等方面有广泛的用途。     

Kinetic studies on MeWO4-tungstates grown under mild hydrothermal conditions (Me=Mn2+, Fe2+, Zn2+)

The reaction mechanims and the kinetics of formation of MeWO₄-tungstates (Me=Mn²⁺, Fe²⁺, Zn²⁺) have been studied by reacting metal (II) chlorides and sodium tungstate at 493 K in a special autoclave, allowing continuous removal of the reactants.

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MeWO₄ ( Me=Mn²⁺, Fe²⁺, Zn²⁺) - (II) 493 , .

     

Synthesis and spectral properties of the Co2+ and Co3+ complexes with octaaryltetraazaporphyrins

Complexes Co²⁺ and Co³⁺ with octaphenyltetraazaporphyrin, octa(4-bromphenyl)tetraazaporphyrin and octa(4-nitrophenyl)tetraazaporphyrin were obtained and identified. The influence of the composition of reaction medium on the oxidation processes of the complexes Co²⁺ → Co³⁺ in DMF was revealed and the optimum conditions of formation of the corresponding compounds were determined.     

Exafs study of Ni2+ coordination in concentrated aqueous solutions

EXAFS measurements are reported for NiCl₂ and Ni(N0₃)₂ aqueous solutions with molar concentrations of about 4, and for crystalline Ni(N0₃)₂·6H₂O. A comparative analysis of the Fourier filtered spectra confirms that the first coordination sphere essentially consists of water molecules. No evidence was found for outer-sphere Cl^? ions approaching closely the inner sphere in NiCI₂ solution.     

Tetraaza 1.4.8.11, cyclotetradecane greffe sur polymere: synthese et application a l'extraction de cu2+, Ni2+ et Co2+.

Polymer-supported cyclam is prepared from 1.4.8.11 tetraaza cyclotetradecane and chloromethylated polystyrene resin. Retention capacities for Cu(II), Ni(II) and Co(II) are reported.     

Optical oscillator strengths of 3p63d 2D → 3p53d22po, 2Do, 2Fo transitions in Co8+, Cu1O+ and Zn11+ ions

We have calculated the excitation thresholds and optical oscillator strengths (OOS) for 3p⁶3d ²D → 3p⁵3d²²po, ²Do and ²F^o transitions Co⁺⁸, Cu¹⁰⁺ and Zn¹¹⁺ ions of the potassium isoelectronic sequence using Hartree-Fock (HF) and configuration interaction (Cl) wavefunctions for both initial and final states. Our Cl values of the length and velocity form of OOS are in good agreement with each other. The trends in the oscillator strengths for the potassium isoelectronic sequence are plotted.     

Kinetics of oxidation of butene-1 to butanone in aqueous solution in the presence of ions Pd2+ and Mo-V-phosphoric heteropoly acid

Oxidation of butene-1 to butanone in the presence of homogeneous catalysts (PdSO₄ + HPA-x), where HPA-x = H_3+xPV_xMo_12-xO₄₀, 1 ￡ x ￡ 4, was investigated. This reaction is found to be of the 1st order with respect to C₄H₈, and of the 0.64th order with respect to Pd. The reaction rate does not depend on the HPA-x concentration and pH of the solution. The activation energy of the reaction is variable. A kinetic expression of the reaction is obtained for 303-343 K. This revised version was published online in June 2006 with corrections to the Cover Date.     

Die Verteilungkoeffizienten von TiO2+, Cr3+, Mn2+ und Fe3+

Ohne Zusammenfassung     

ESR spectra and magnetic constants of α-Al2O3:Co2+,H+ and α-Al2O3 :Co2+,X+

New anisotropic ESR spectra of Co²⁺ doped sapphire, different from hitherto known, are reported. The new spectra which are observed, beside the well-known spectra of α-Al₂O₃:Co²⁺, are shown to form two sets, each one consisting of six spectra (1–6) and (7–12). The spectra of both sets are proven to be interrelated by B_3a symmetry. g and A tensors for each set will be given. Evidence is given that the two sets are to be assigned to the defects α-Al₂O₃:Co²⁺,H⁺ and α-Al₂O₃:Co²⁺,X⁺. The former is concluded to consists of a Co²⁺ ion at the substitutional site (c) and a proton located in a potential minimum along a straight line between O^2- ions situated in O²⁺ triangles above and below the CO²⁺ ion. The potential function for the proton has been calculated by quantum-chemical calculations to clucidate the geometrical structure of the paramagnetic center. The α-Al₂O₃:Co²⁺,X⁺ could not be fully analyzed but some evidence is presented, that X⁺ might be alkali ions.     

基于香豆素Schiff碱的Zn2+、Co2+和Ni2+配合物的合成、晶体结构及光谱性质

合成了3个香豆素Schiff碱单核Zn²⁺、Co²⁺和双核Ni²⁺的配合物，[Zn（L¹）₂]（1）（HL¹=6-（（4-二乙胺基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮），[Co（L²）₂]（2）（HL²=6-（（4-甲氧基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮），[Ni₂（L³）₂（CH₃OH）₄）]（3）（H₂L³=4-羟基-3-（（4-甲氧基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮）。利用元素分析、红外光谱、紫外可见光谱、荧光光谱及X射线单晶衍射分析等手段对其进行了表征。X射线单晶衍射分析结果表明：配合物1和配合物2均为单核结构，由1个金属离子和2个配体单元组成；配合物3具有双核结构，由2个金属离子、2个配体单元及4个配位的甲醇分子组成。配合物1、2和3分别是单斜晶系、三斜晶系和三斜晶系，所属的空间群分别为C2/c、P1和P2₁/n；中心金属Zn²⁺和Co²⁺离子的空间构型为四配位的四面体，Ni²⁺离子的空间构型为六配位的扭曲的八面体。此外，通过对配体HL¹和HL²的紫外可见光谱性质研究发现，在DMF/H₂O（4：1，V/V）溶液中，自由配体HL¹和HL²分别可以选择性识别Hg²⁺和Zn²⁺，通过计算得到其检测限分别为7.45和6.10 μmol·L^-1。荧光性质研究发现在DMF/H₂O（4：1，V/V）溶液中自由配体HL²可以检测Zn²⁺，检测限为2.91 μmol·L^-1。     

CO32-/Co2+/Ni2+浓度对混合相纳米Ni(OH)2物化性能的影响

以NiCl2、Co(NO3)2、Na2CO3为主要原料,采用超声波辅助沉淀法制备了混合相纳米Ni(OH)2,研究了Co掺杂比例、缓冲剂Na2CO3用量及反应物Ni2+浓度对Ni(OH)2的晶相结构、形貌、粒径及电化学性能的影响。结果表明,混合相结构的α-Ni(OH)2成分随Co掺杂比例增大而增加。较高的CO32-和Ni2+浓度有利于α-Ni(OH)2的生成。TEM测试表明,样品晶粒呈针状形态,其长径比随着Na2CO3用量增加而减小,平均粒度在60~90 nm之间。将纳米样品以8wt%与工业用微米级β球镍混合制成复合电极,其电极的放电比容量随Na2CO3用量的增加先增大后减小。当Ni2+浓度为0.4 mol.L-1、Na2CO3用量为0.5 g时,其电极(Co含量1.02wt%)的充电效率最高,放电比容量最大,0.5C倍率下高达306.9 mAh.g-1,比纯球镍电极提高30%。探讨了复合电极能较大幅度提高放电比容量的机理,提出纳米α-Ni(OH)2同时充当活化中心起催化作用的观点。     

Zur quantitativen Bestimmung von Zn2+, Pb2+, Al3+ und Cr3+

Ohne Zusammenfassung     

Investigation of the Mn2+-F− distance for Mn2+ in fluoride lattices with hexahedral coordination

The Mn²⁺-F^? distance for Mn²⁺-doped CaF₂, CdF₂, SrF₂ and BaF₂ is derived from the experimental isotropic superhyperfine constant A_s. The results obtained indicate the existence of inwards relaxation processes in all these cases, as well as values of the Mn²⁺-F^? distance which are ≈0.1 A larger than those found for systems with [MnF₆]^4? units. This allows one to explain the low 10D_q values recently found by Alonso an Alcalá in CdF₂: Mn²⁺.     

Durch elektrochromatographische Untersuchung der komplexen Laurate von Co2+, M2++ und Cu2+

Ohne Zusammenfassung