Two Keggin Templated Supramolecular Compounds by Exerting the Chelate and Linking Dual Roles of the Ligand 2, 2′‐Biimidazole

Two new Keggin templated supramolecular compounds, [Zn₂(H₂biim)₅(SiM₁₂O₄₀)] · 4H₂O [M = W ( 1 ), Mo ( 2 )] (H₂biim = 2, 2′‐biimidazole), were synthesized under hydrothermal conditions by using the ligand 2, 2′‐biimidazole. They were characterized by single‐crystal X‐ray diffraction, elemental analyses, IR and photoluminescence spectroscopy as well as cyclic voltammetry. The two isostructural compounds are constructed by two discrete supramolecular moieties: the inorganic chains consist of Keggin anions and metal‐organic chains constructed by [Zn₂(H₂biim)₅]⁴⁺ subunits. In the dinuclear [Zn₂(H₂biim)₅]⁴⁺ subunit, the H₂biim ligands exhibit a dual role, chelating and linking. The metal‐organic chains further construct a 3D supramolecular framework with channels, in which the Keggin‐based inorganic chains are accommodated. The electrochemical behaviors of compounds 1 and 2 bulk‐modified carbon paste electrodes ( 1 ‐CPE, 2 ‐CPE) were studied.     

Synthesis,Crystal Structures and Properties of Two New ­Coordination Polymers Constructed from in situ‐generated Pyridyl‐dicarboxylic Acid Ligands

Two novel coordination polymers [Mn₃(EPDA)₂(H₂O)₈ · (ENA) · (ClO₄) · 0.5(HClO₄) · (CH₃OH) · 2(H₂O)]_n ( 1 ) and[Zn(EPDA)(H₂O)]_n ( 2 ) (EPDA = 5‐ethylpyridine‐2, 3‐dicarboxylic acid, ENA = 5‐ethylnicotinate acid) were synthesized and characterized by IR and UV/Vis spectroscopy, elemental analysis, PXRD, TGA, photoluminescence, and single‐crystal X‐ray diffraction. Organic EPDA^2– and ENA^– anions, the decomposition products of ENA‐Pmmi by removing the –Pmmi group under in situ solvothermal conditions, were obtained by performing the reactions of ENA‐Pmmi with Mn^II or Zn^II perchlorate. In complex 1 , the Mn^II ions were bridged by μ₄‐EPDA^2– anions to give a 2D positively charged layer, and the free ENA^– anion and solvent molecules are filled into the gap between the layers through hydrogen bonding interactions to form a sandwich structure. In compound 2 , the μ₃‐EPDA^2– anions bridge divalent Zn²⁺ ions to form a 1D chain, and the ENA^– anions are not involved in stacking interactions but left in the residual solution. In addition, the ENA‐Imoi instead of ENA‐Pmmi, was selected to further investigate this reaction (ENA‐Pmmi and ENA‐Imoi are imazethapyr homologues), and the same experimental results could be obtained.     

CRYSTAL STRUCTURE AND THERMAL ANALYSIS OF A 4,4′-BIPY-BRIDGED BINUCLEAR ZINC(II) COMPLEX, 2[R2NCS2]2 · Zn(4,4′-BIPY) (R=PIPERIDYL)

Abstract

The crystal structure of the title complex 2[R₂NCS₂]₂ · Zn(4,4′-bipy) (R = Piperidyl), 1, revealed that it consists of dimers made up from two crystallographically independent molecules. Each zinc atom in 1 forms a 5-coordinate pseudo-square-based pyramidal arrangement (with four Zn-S and one Zn-N interactions). Bondlengths to Zn with the coordinating atoms are comparable to those in other Zn(II) dithiocarbamate complexes. The piperidine ring has a chair conformation. To allow improved packing, the title complex molecules form an approximately linear arrangement extending along both a and b. TGA showed that 1 is decomposed in two close steps to produce ZnS as identified by residual weight. The complex 1 crystallizes in the monoclinic space group C2/c with cell parameters: a = 22.021(5), b = 22.215(3), c = 17.537(2) Å, β = 93.49(2)°, V = 8563(3) ų and Z = 8. The structure was refined by full-matrix least-squares methods to R = 0.067, R_w = 0.114.     

Synthesis and Characterization of Nitrato-Triamine-Metal(II) Complexes. Conglomerate Crystallization Part 55. Crystal Structure of [Ni(dien)(O2NO)(ONO2)] (I), {[Cu(dien)-(μ-ONO2)]NO3}∞ (II), [Zn(dien)(O2NO)(ONO2)] (III), [Ni(Medpt)(O2NO)(ONO2)] (IV) and [Cu(Medpt)(ONO2)2] (V)

In absolute ethanol and in the presence of triethylorthoformate, reactions of metal(II) nitrates with linear tridentate amines afforded metal complexes of the formula M(NNN)(NO₃)₂, where M = Ni²⁺, Cu²⁺ and Zn²⁺, and NNN = dien and Medpt. The compounds fall into three categories in accordance with their stereochemistry and mode of binding of the nitrato ligands. Compounds I, [Ni(dien)(O₂NO)(ONO₂)] and III, [Zn(dien)(O₂NO)(ONO₂)] are isomorphous and isostructural. They crystallize in the monoclinic space group P2₁/n with nearly identical cell constants. The stereochemistry of these two compounds is such that the terdentate dien ligand forms a fac MN₃ moiety with the two oxygens of the bidentate nitrato ligand trans to the terminal NH₂. These ligands form the base of the octahedral arrangement in which the sixth position, trans to the secondary nitrogen of the dien, is an oxygen of the monodentate nitrato ligand. Compound IV, [Ni(Medpt)(O₂NO)(ONO₂)] falls into the same category as I and III despite the fact that the two rings in the Ni-Medpt moiety are six-membered rings, unlike those in compounds I and III which are five-membered rings. Nevertheless, the nickel-amine arrangement is fac. The bidentate nitrato-oxygens are trans to the terminal NH₂ of the amine ligand, and the oxygen of the monodentate nitrato ligand is trans to the tertiary amine-nitrogen. Such stereochemistry is prevalent for nickel and zinc compounds. Interestingly, compound IV crystallizes as a conglomerate (space group P2₁2₁2₁). Compound II, {[Cu(dien)(μ-ONO₂)]NO₃}_∞ belongs to the second category and has a polymeric structure. The repeating fragment in the polymeric chain is a Cu(dien)-O fragment with the monodentate nitrato ligand occupying an equatorial position of the base. A second oxygen of the equatorial nitrate becomes an axial ligand for an adjacent Cu-N₃O fragment. In this way the substance propagates into an infinite chain. The repeating unit has an effective square pyramidal, five-coordinate, configuration. Finally, the compound crystallizes as a racemate. The second nitrate necessary for charge compensation of this copper(II) compound is ionic and its function is to hold the infinite chains of the lattice. The third category represented by compound V, [Cu(Medpt)(ONO₂)₂] contains two molecules in the asymmetric unit of the racemic lattice (monoclinic, space group P2₁/a). The structure of Cu-Medpt is unlike that of IV in that both species present in the asymmetric unit have the amine ligand in a mer configuration which together with a monodentate oxygen of a nitrato ligand form a base plane of a square pyramid. The fifth ligand of both Cu²⁺ ions is a second monodentate nitrato ligand. The stereochemical differences between the two Cu²⁺ ions are insignificant for the Cu-Medpt fragment, which share the same conformation and configuration. The major difference between the two species is the torsional angles defined by the Cu-O-N-O angles. The difference arises from variation in the hydrogens of the primary amine moieties selected by nitrato-oxygens to form intramolecular hydrogen bonds. Finally, there is a little variation in the equatorial Cu-ONO₂ stereochemistry because of steric hindrance, imposed by the Medpt, preventing large torsional angles by these nitrato ligands. This is evident by comparing the two copper species shown in Finally, nitrate-to-Br ligand exchange was found to take place when KBr pellets are prepared for IR spectral measurements.     

Synthesis and Crystal Structures of Two Zinc(II) Complexes with the Tripodal Ligand Tris(2-Benzimidazolymethyl)Amine

This article reports the synthesis and crystal structures of two new mononuclear Zinc(II) complexes, [Zn₂(NTB)₂(N₃)₂](NO₃)₂·2CH₃OH (1) and [Zn₂(NTB)₂(SCN)₂](NO₃)₂·2CH₃OH·H₂O (2). Complex 1 crystallizes in the triclinic system, space group P&1macr;, a=13.743(4), b=14.374(4), c=14.443(5) Å; α=77.053(5), β=81.824(5), γ=88.959(6)°; Z=2; R1=0.0418, wR2=0.0889. Complex 2 also crystallizes in the triclinic system, space group P&1macr;, a=12.203(10), b=14.430(12), c=18.541(15)Å; α=72.712(15), β=85.039(15), γ=73.610(14); Z=2; R1=0.0771, wR2=0.1288. In both cases the central zinc(II) metal ions are coordinated to the four nitrogen atoms of NTB and a nitrogen atom of N^- ₃(1) or SCN^-(2) to form distorted trigonal bipyramidal coordination spheres.     

CO2选择性氧化甲烷制C2烃催化剂La2O3/ZnO的氧化还原和CO2吸附性能

Ｌａ２Ｏ３／ＺｎＯ催化剂体系在以二氧化碳作为氧化剂的甲烷氧化偶联反应中具有很高的Ｃ２烃选择性和稳定性．采用ＣＯ２－ＴＰＤ－ＭＳ和ＴＰＲ技术考察了Ｌａ２Ｏ３／ＺｎＯ对ＣＯ２的吸附性质及其氧化还原行为．结果表明：（１）Ｌａ２Ｏ３／ＺｎＯ催化剂体系存在着强、弱两种碱中心，其中弱碱中心数量随样品中Ｌａ２Ｏ３含量增加而减少，强碱中心强度随样品中Ｌａ２Ｏ３含量增加而增强．（２）由于组分相互作用，高温下，Ｌａ２Ｏ３／ＺｎＯ易产生晶格氧空位，使之对ＣＯ２的吸附增强，吸附后的ＣＯ２与晶格氧作用形成立方晶型Ｌａ２Ｏ２ＣＯ３．（３）Ｌａ２Ｏ３／ＺｎＯ表面的Ｌａ３＋和Ｚｎ２＋可以部分被还原，由于组分间的相互作用，使得二者的还原都较单一组分存在时更难．（４）Ｈ２－ＣＯ２－Ｈ２氧化还原循环实验表明，Ｌａ２Ｏ３／ＺｎＯ表面被部分还原后，ＣＯ２可以将部分被还原的表面再氧化．在此基础上对Ｌａ２Ｏ３／ＺｎＯ催化剂上甲烷与ＣＯ２转化为Ｃ２烃的机制也进行了讨论．     

甲醇与乙醇一步合成异丁醛用CuO-ZnO/Al2O3催化剂

在ＣｕＯ－ＺｎＯ／Ａｌ２Ｏ３催化剂上，甲醇与乙醇在常压和２１０￣３６０℃温度下一步反应合成异丁醛。利用正交设计方法，研究了ＣｕＯ－ＺｎＯ／Ａｌ２Ｏ３体系催化剂组成和制备条件等因素对催化剂催化性能的影响。结果表明，催化剂中ＣｕＯ含量对催化剂的催化活性影响最大，而ＺｎＯ含量则主要影响催化剂对异丁醛的选择性。催化剂制备条件，如沉淀温度、陈化时间等，也不同程度也影响催化剂的催化性能。ＸＲＤ和ＢＥＴ表征结果     

亚临床肝性脑病患者的血清锌,铜含量的测定及临床意义

检测了３０例慢性活动性肝炎患者、３０例肝硬化患者、３０例亚临床肝性脑病患者血清中的铜、锌含量，并与正常对照组进行比较分析，探讨了微量元素铜、锌的血清含量改变及其影响因素，分析其临床意义。结果表明体内的铜锌含量与肝脏功能有密切的关系。在慢性活动性肝炎时，虽然肝脏功能有一定的损害，但由于肝脏的代偿能力强，铜，锌含量仍可保持在正常水平，而在肝硬化、亚临床肝性脑病时，铜锌明显降低，而铜锌含量的降低又导致机     

Zinc mediated reductive dimerization and cyclization of α,β-unsaturated ketones in the presence of a catalytic amount of mercury(II) chloride

The zinc mediated reductive dimerization and cyclization of α,β-unsaturated ketones gives functionalized cyclopentanols in good yield in the presence of a catalytic amount of mercury(II) chloride in N,N-dimethylformamide as solvent at room temperature. The reaction is regio- and stereo-selective producing 3,4-trans-diarylcyclopentanols selectively.     

Highly Sensitive Differential Pulse Voltammetric Determination of Cd,Zn and Pb Ions in Water Samples Using Stable Carbon‐Based Mercury Thin‐Film Electrode

A new carbon‐based mercury thin‐film electrode consisting of screen‐printed carbon on a low temperature co‐fired ceramic substrate was made. Ex‐situ mercury deposition in a potassium thiocyanate solution was used. This approach an electrode with high long‐term stability (>500 measurement cycles) and reproducibility (≤2 %) for sensitive determination of ultra trace heavy metals, using differential pulse anodic stripping voltammetry. The detection limits were 0.25, 0.08 and 5.5 ng mL^?1 for Cd(II), Pb(II), and Zn(II), respectively. The method was applied to the determination of the analytes in water, wastewater, lake water, and certified reference material samples with satisfactory results.