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排序方式: 共有201条查询结果,搜索用时 31 毫秒
81.
82.
Shabnam Sheshmani Parvaneh Dalir Kheirollahi Hossein Aghabozorg Ardeshir Shokrollahi Guido Kickelbick Mojtaba Shamsipur Farshid Ramezanipour Abolghasem Moghimi 《无机化学与普通化学杂志》2005,631(15):3058-3065
The two complexes (pydaH)2[Ce(pydc)2(H2O)2]2 · 2H2O (1) and (phenH)2[Bi(pydc)2(H2O)]2 · 5H2O (2) were prepared from the proton transfer compounds containing the 2,6‐pyridinedicarboxylate ion. 1 was synthesized from the reaction of Ce(NO)3 · 6H2O with the proton transfer compound, (pydaH2)(pydc), (pyda=2,6‐diaminopyridine, pydcH2=2,6‐pyridinedicarboxylic acid). 2 was synthesized from the reaction of proton transfer compound, (phenH)2(pydc), (phen=1,10‐phenanthroline), with Bi(NO3)3 · 5H2O. The characterization was carried out using IR, 1H and 13C NMR spectroscopy, elemental analysis and single crystal X‐ray diffraction. The complex 1 crystallizes in the space group of the triclinic system, and contains two molecules per unit cell. The structure has been refined to a final value for the crystallographic R factor of 0.0342 based on 8851 reflections. The unit cell parameters are: a = 9.753(2) Å, b = 10.503(2) Å, c = 10.774(2) Å, α = 83.905(4)°, β = 88.089(4)°, and γ = 82.636(3)°. The crystal structure illustrates that cerium atoms are connected together through the four‐membered ring Ce2O2. 2,6‐Pyridinedicarboxylate fragment acts as a tridentate ligand. The molecular structure contains four (pydc)2? ligands, two of which are bridge ligands linking the two central atoms. The complex 2 crystallizes in the space group of the triclinic system and contains two molecules per unit cell. The unit cell dimensions are: a = 8.8860(4) Å, b = 12.0132(6) Å, c = 13.0766(6) Å, α = 100.967(1)°, β = 96.681(1)° and γ = 94.191(1)°. The structure has been refined to a final value for the crystallographic R factor of 0.0471 based on 9576 reflections. In this complex, 2,6‐pyridinedicarboxylate moiety has acted as a tridentate ligand and the lattice is composed of binuclear unit, [Bi(pydc)2(H2O)]22?, (phenH)+ counter ions and five lattice waters. In both complexes hydrogen bonds, π‐π stacking and ion‐pairing play important roles in stabilizing the corresponding lattice. The stoichiometry and stability of the ZnII, CdII, PbII, and CeIII complexes with (pydaH2)(pydc) in aqueous solution were investigated by potentiometric pH titration. The solution studies revealed that the stoichiometry of the crystalline complexes of the proton transfer system (pydaH2)(pydc) with CeIII, obtained in this study, and those with ZnII, CdII and PbII, reported in our previous studies, are in close agreements. The complexation reactions of phen, pydc, and 2phen+pydc with BiIII in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described. 相似文献
83.
Zaira J. Cárdenas Ovidio A. Almanza Abolghasem Jouyban William E. Acree Jr 《Physics and Chemistry of Liquids》2018,56(1):16-32
The mole fraction solubility of phenacetin (PNC) in methanol + water binary solvent mixtures at 298.15 K was determined along with density of the saturated solutions. All these solubility values were correlated with the Jouyban–Acree model. Preferential solvation parameters of PNC by methanol (δx1,3) were derived from their thermodynamic solution properties using the inverse Kirkwood–Buff integrals (IKBI) method. δx1,3 values are negative in water-rich mixtures but positive in methanol mole fraction of >0.32. It is conjecturable that in the former case the hydrophobic hydration around non-polar groups of PNC plays a relevant role in the solvation. The higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behaviour of methanol. 相似文献
84.
Zaira J. Cárdenas Daniel M. Jiménez Ovidio A. Almanza Abolghasem Jouyban William E. Acree 《Physics and Chemistry of Liquids》2018,56(4):465-481
The equilibrium solubility of benzocaine (BZC) in several {methanol (1) + water (2)} mixtures at 298.15 K was determined. Solubility values are expressed in mole fraction and molarity and were calculated with the Jouyban–Acree model. Preferential solvation parameters of BZC by methanol (δx1,3) were derived from their thermodynamic solution properties using the inverse Kirkwood–Buff integrals method. δx1,3 values are negative in water-rich mixtures (0.00 < x1 < 0.32) but positive in the other mixtures (0.32 < x1 < 1.00). To explain the preferential solvation by water in the former case, it is conjecturable that the hydrophobic hydration around non-polar groups of BZC plays a relevant role in the solvation. Moreover, the higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behaviour of methanol regarding water. 相似文献
85.
86.
87.
Phosphated tungstate as a new, reusable and efficient solid phosphoric acid catalyst was synthesized and used to promote the reaction of diaminoglyoxime with various aromatic aldehydes. The prepared phosphated tungstate was characterized using various techniques including X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. A wide variety of heterocyclic nitrones were obtained under mild reaction conditions and in high yields by using the prepared catalyst. 相似文献
88.
89.
Abolghasem Moghimi Rahim Hosseinzadeh Khanmiri Ahmad Shaabani Homayoon Hamadani 《Journal of the Iranian Chemical Society》2013,10(5):929-936
The reaction of diaminoglyoxime with aldehyde and ketone derivatives in the presence of p-toluene sulphonic acid in H2O–MeOH mixture at room temperature afforded nitrone derivatives in high yields within 10–140 min. The applicability of ketones in this reaction for the preparation of novel nitrones has been verified. The effect of the temperature on the stability of the structural isomers of the products has been studied by NMR as well. The results showed that, at high temperatures only one product could be observed. The nature of solvent and catalyst were evaluated and found that the strong acids H2SO4 and CF3SO3H in protic solvent CH3OH work well while neither CH3SO3H in protic solvent nor p-toluene sulphonic acid in aprotic solvents toluene and THF perform the same reactions. 相似文献
90.
Khodabakhsh Niknam Ali Reza Kiasat Foad Kazemi Abolghasem Hossieni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1385-1389
Aromatic nitro compounds can be conveniently reduced to the corresponding primary amines in the presence of S 8 under solvent-free conditions in excellent yields. Alumina supported NaOH catalyses this transformation. Chemoselectivity was observed in the reduction of the nitro group in the presence of phenol, carboxylic acid, aldehyde, and benzyl halide groups. 相似文献