本文用示差脉冲极谱技术研究Pb(Ⅱ) 络合剂(β N 三丙酸)体系。依据实验得到的极谱峰电位的移动随溶液pH值的变化关系曲线,建立合适的金属络合物体系模型。用计算机分析程序,通过求解体系的质量平衡方程及拟合实验络合物形成曲线,优化得到金属络合物的稳定常数。计算机分析结果表明,在所研究的pH值范围内,溶液中存在四种金属络合物:PbH2L+、PbHL、PbL-、PbL(OH)2-,其稳定常数(logβ)分别为:16.23±0.04、12.42±0.01、4.11±0.05、9.43±0.02。 相似文献
Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH2O/Li+, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH2O?/Li+, the C2v-conformer of the 2A1-state with the equilibrium bond distances of d(C? O) = 1.23 Å and d (O? Li) = 1.90 Å is calculated to be more stable than the 2B1-state with d (C? O) = 1.34 Å, and d (O? Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed. 相似文献
The molecular encapsulation of two purine derivatives, caffeine and acyclovir by hydroxypropyl-β-cyclodextrin (HPBCD) in water solution has been studied at 25 °C by fluorescence spectroscopy. When the inclusion complex is formed, changes in the fluorescence spectra of the drugs enable the calculation of the association constants of the binding process, by using a nonlinear regression analysis of the experimental data at three different λem. The inclusion of the drugs into the CD cavity has been supported by preliminary docking studies. The resulting binding constants have been also discussed in terms of the control release of both purine derivatives, evaluating the HPBCD herein studied as a suitable vector for these drugs. 相似文献
The porphyrins is a kind of sensitive color-producing reagent. However, its selectivity is low. If the porphyrin is used in polarographic analysis, the selectivity and sensitivity can be improved. Copper is one of the most important trace element in human and mammalian body. The polarographic method is a kind of important method in determination of metal ion [1]. In this paper, meso-tetra (4-sulfonylphenyl) porphyrin (H2TPPS4) is used as the soluble ligand. The polarographic absorption behavior of meso-tetra (4-sulfonylphenyl) porphyrin complex with copper ion has been studied. 相似文献
Summary: Polyisoprenes were found to form inclusion complexes with cyclodextrins with high selectivity to give crystalline compounds. β‐Cyclodextrin formed complexes only with polyisoprene of low molecular weight, whereas γ‐cyclodextrin formed complexes with polyisoprenes of high molecular weight. α‐Cyclodextrin did not form complexes with polyisoprene of any molecular weight. The yields of γ‐cyclodextrin complexes increased with increasing molecular weights of the polyisoprenes and reached a maximum of around several thousands, and then decreased.
Theoretical depiction of the complex formed between polyisoprene and γ‐CD, as determined by molecular modelling studies. The PIP chain is shown penetrating the γ‐CD cavity, which, in turn, accommodates one to 1.5 monomer units of PIP. 相似文献
In this paper the Bi(Ⅲ)-ligand(pyridine-2-carboxylic acid) system was studied by direct current sampled polarography (DC_TAST) at a fixed ratio of total-ligand to total-metal concentration and changing pH. The po-larographic experimental complex formation curve (ECFC) and the theoretical complex formation curve (TCFC) were used for modelling the metal-ligand system and optimizing stability constants. The ECFC， in which experi-mental parameters of polarography are included (a shift in a half-wave potential and a variation in a diffusion controlled limiting current)， appears to be a characteristic function for a particular metal-ligand system. The TCFC is a theoretical curve calculated for the designed metal-ligand model from mass-balance equation. Five bismuth complexes MHL， ML， ML2， ML3 and ML3(OH) with their stability constants as logβ 7.54±0.10， 7.50±0.02， 13.91±0.04， 18.15±0.03 and 26.75±0.02， respectively， are reported. 相似文献
The thermometric titration of titanium(III) chloride with oxalic acid was carried out at 25°C. The molar ratio of titanium (III): oxalate was found to be 1:2, which indicates the formation of Ti(C2O4)2− ion in acid media. The limiting value of the heat of reaction between Ti(III) ion and oxalic acid in hydrochloric acid solution was found to be −1.5 Kcal mole−1 at 25°C. 相似文献
