排序方式: 共有340条查询结果,搜索用时 15 毫秒
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Hossein Aghabozorg Elham Motieiyan Ali R. Salimi Masoud Mirzaei Faranak Manteghi Ardeshir Shokrollahi Somayeh Derki Mohammad Ghadermazi Shabnam Sheshmani Hossein Eshtiagh-Hosseini 《Polyhedron》2010
The novel title compounds, (pipzH2)1.5(pydcH)3·3.7H2O, 1, (pipzH2)[Zr(pydc)3]·8H2O, 2 and (pipzH2)[Ce(pydc)3]·8H2O, 3 in which pydcH2 is pyridine-2,6-dicarboxylic acid and pipz is piperazine were obtained in aqueous solution. The compounds were characterized by IR, 1H NMR and 13C NMR spectroscopy, elemental analyses, and X-ray crystallography. Compound 1 is resulted from proton transfer between pydcH2 and pipz. However, compounds 2 and 3 are resulted from complexation of 1 and corresponding metallic salts. Both compounds 2 and 3 contain three pyridine-2,6-dicarboxylate species as tridentate ligands, one piperazinediium as counter ion, and eight-uncoordinated water molecules in the asymmetric unit. In both structures each M(IV) is coordinated in a distorted tricapped trigonal prism geometry by three nitrogen and six oxygen atoms of carboxylate groups of three (pydc)2− fragments. In the crystal structures of 1, 2 and 3, extensive O–H···O, N–H···O and C–H···O hydrogen bonds as well as electrostatic forces, C–H···π, C–O···π and π–π stacking play important roles in stabilizing structures. The geometrical parameters of the [M(pydc)3]2− anionic complexes, where M = Ce(IV), Zr(IV) have been optimized with the B3LYP method of density functional theory (DFT) and ab initio Hartree–Fock (HF) methods for comparison. In addition, we have studied the structures of (pydc)2− anion and its mono and doubly protonated forms, (pydcH)− and pydcH2. The electronic properties of the anionic complexes and ligands have been investigated based on the natural bond orbital (NBO) analysis at the B3LYP method which verifies that the synergistic effect has been occurred in the title complexes. In solution study of 2, the stoichiometry and stability constant of complexation of pipz, pydc, pydc–pipz proton transfer system and Zr(IV) ion in aqueous solution were investigated by potentiometric method. 相似文献
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Jamal Davarpanah Parizad Rezaee Somayeh Elahi 《Research on Chemical Intermediates》2015,41(12):9903-9915
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A one-pot four-component synthesis of imidazo phosphates has been achieved using a Nef/Perkow sequence followed by addition of propargylamine to form an intermediate amidrazone. The latter is not isolated but directly cyclized to imidazo phosphate derivatives in the presence of silver carbonate. 相似文献
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Hossein Soltani Hadi Beitollahi Abdol-Hamid Hatefi-Mehrjardi Somayeh Tajik Masoud Torkzadeh Mahani 《Ionics》2014,20(10):1481-1488
A carbon paste electrode modified with benzoylferrocene (BF) and carbon nanotubes (CNTs) have been applied to the electrocatalytic oxidation of homocysteine which reduced the overpotential by about 165 mV with an obvious increase in the current response. The transfer coefficient (α) for the electrocatalytic oxidation of homocysteine and diffusion coefficient of this substance under the experimental conditions were also investigated. In a phosphate buffer solution (PBS) of pH 7.0, the oxidation current increased linearly with two concentration intervals of homocysteine; one is 0.1 to 10.0 μM, and the other is 10.0 to 80.0 μM. The detection limit (3σ) obtained by square wave voltammetry (SWV) was 50.0 nM. The proposed method was successfully applied to the determination of homocysteine in real samples. 相似文献
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