共查询到19条相似文献,搜索用时 134 毫秒
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本用双系列线性回归法研究了Pb(Ⅱ),Zn(Ⅱ)与5-Br-PADAP的络合反应,发现在pH5-6.5,30%乙醇溶液中,Pb(Ⅱ)与5-Br-PADAP形成1:1络合物,Zn(Ⅱ)主要形成1:2络合物。两种络合物的稳定常数(1gβ)分别为11.17,22.31,最大吸收波长分别为575,550nm,摩尔吸光系数分别为6.01×10^4,1.34×10^5L.mol^-^1.cm^-^1。 相似文献
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报道了Zn、Mg、Pb和Hg与TTHA形成的2:1双核配合物的动态NMR研究,在所研究的温度范围内观测到Zn2TTHA分子内重排过程,并通过模拟谱求出分子内重排过程的速率常数,提出Zn2TTHA在溶液中的构型由2个对称的八面体单元组成,而不是由2个四面体构成的;用二位交换的Bloch方程估计Mg、Pb和Hg双核配合物的活化能Ea值;发现分子内重排活化能大小的顺序与中心金属离子的离子势呈线性关系。 相似文献
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结合光谱测定和量子化学理论计算(INDO/S)结果探讨了在双核金属酞菁类化合物催化下以O_2作氧源的氧化─还原反应中,分子O_2与催化剂分子的键合及荷移方式.循环伏安测定表明催化反应过程中O_2与催化剂分子结合,且被活化;ESR及IR光谱显示O_2被活化后的形式为;吸收光谱则表明催化剂在活化氧后其中心金属离子由M(Ⅱ)变为M(Ⅲ).INDO/S计算结果表明双核金属酞菁类化合物具有两种稳定结构M(Ⅱ)Pc──PcM(Ⅱ)和M(Ⅰ)Pc──PcM(Ⅲ),且后者相对更稳定.分子O_2与催化剂分子的键合方式为端配位,就M─O键强度和对O_2分子活化性能的比较而言存在顺序:O_2─M(Ⅰ)Pc>O_2─M(Ⅱ)Pc>O_2─M(Ⅲ)Pc. 相似文献
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Chen JS Wu CC Kao DY 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(10):2287-2293
The dimerization of 2,2-dimethyl-3-ethyl-3-pentanol in tetrachloroethylene in the diluted region has been studied at four temperatures by IR spectroscopy. The aforementioned solute compound is chosen because self-association beyond dimerization is hampered by the steric hindrance generated by the bulky sidechains. The integrated absorbances of the monomer bands were treated based on Eq. (9) to obtain its molar absorptivity and dimerization constant. The same dimerization constant as well as the molar absorptivity of dimer band can be obtained based on Eq. (13) from the data treatment of the integrated absorbances of the dimer band. The disparity between two values of dimerization constant determined by two independent sources offers an opportunity to check the consistency of the determination. The standard enthalpy and entropy of dimerization have also been calculated by means of van't Hoff plot, respectively, from the data of temperature-dependent dimerization constants obtained from the monomer bands and dimer bands. 相似文献
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本文合成了苯并[15-冠-5]取代的酞菁化合物,研究了铷离子诱导的冠醚酞菁二聚行为的光谱特性,观察到冠醚酞菁形成二聚体的光谱变化分三阶段进行,与铷离子的浓度密切相关,这是由于二聚体中酞菁环从非共平面构象最终转变为面对面的超分子结构的结果;详细介绍了对紫外可见吸收光谱中重叠光谱的数据处理方法,从而计算了二聚体形成的平衡常数K值。 相似文献
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Determination of the dimerization constant of pinacyanol: role of the thermochromic effect 总被引:1,自引:0,他引:1
Sabaté R Estelrich J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(2):471-476
Pinacyanol (PIN), as other cyanine dyes, has demonstrated a unique ability to form associates such as dimers, and H- and J-aggregates. This association is strongly favoured in water, and even at low dye concentrations, dimers and superior order aggregates are present. As a consequence, the determination of the dimerization constant involves sometimes a significant error when these aggregates are neglected. As an increase in temperature shifts the equilibrium among the different species towards the lowest order aggregates, we have obtained the spectra of PIN at several temperatures. By extrapolating some spectral characteristics at high temperatures, a spectrum of the dimer without any contribution of other aggregates was obtained. From this spectrum and that of the monomer, the dimerization constant was calculated, as well as the Gibbs energy change associated to the reaction. The enthalpy and entropy changes of the dimerization were determined from the dependence of the dimerization constants on the temperature. From these results it can be inferred that the driving force of the dimerization is of enthalpic origin. 相似文献
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研究了meso-四(4-磺基苯基)卟啉(TPPS)在胶束(TritonX-100)、KCl水溶液中的电子吸收光谱变化,计算了TPPS的二聚常数KD,用分光光度法研究了TPPS在KCI水溶液中的二聚反应动力学,提出了与实验结果相吻合的二聚机理.根据温度对二聚平衡的影响,计算了二聚平衡的乙和 相似文献
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本文研究了二磺化酞菁镓(S2PcGa)、三磺化酞菁(S3Pc)在胶束(TritonX-100)中的二聚行为。计算了S3Pc、S2PcGa在胶束中的二聚常数KD及分配系数K。并对磺化酞菁在胶束中的增敏,解聚机理进行了探讨。 相似文献
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自退卷积(self-deconvolution)方法增强光谱分辨的理论随着计算机技术的发展到七十年代已达到实用阶段。Fourier自退卷积(以下简写为FSD)已成为一个常规应用的计算程序。它丰富并扩大了Fourier红外光谱的应用。FSD方法较之其它分辨力增强方法,例如导数光谱,谱带拟合方法等具有直观和最大限度保持谱峰结构信息等优点。当然应用这项技术时需谨慎选择计算参数,并要对所要求解决的问题有所估计,不致使谱带变形过渡而导 相似文献
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Eichwurzel I Stiel H Röder B 《Journal of photochemistry and photobiology. B, Biology》2000,54(2-3):194-200
This work reports on a monomer-dimer equilibrium state of pheophorbide a in solution. A methodology for controlling the equilibrium constant by use of temperature and solvent variation is described. The absorption spectrum of the dimer is calculated, using different prepared equilibria of monomer and dimer in solution. We propose that these aggregates provide a good model for understanding the dimerization process in tetrapyrroles. 相似文献
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A variable force field model for radical dimerization was developed. It uses MM2 force constants for most atoms and new parameters only for the core atoms involved in bonding changes. The change in hybridization from sp2 to sp3 is modeled using distance-dependent switch functions. The validity of the model has been tested by calculating the minimum energy path of the dimerization of di-tert-butylmethyl radicals. The calculated and experimental values for the enthalpy of activation of both dimerization of the radicals and dissociation of the dimer are in excellent agreement. The model has also been successfully applied to the stereoselective dimerization of 1-phenylneopentyl radicals: The form of the potential energy surface yields an explanation for the observed stereoselectivity. Another common feature in radical dimerization seems to be the formation of adsorption complexes prior to dimerization that can lead to increased reactivity. The results suggest that it is important to analyze the whole reaction path and not only the transition state alone. 相似文献
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The extraction of HC1 by the secondary amine (B), known as Amberlite LA-2, dissolved in 1,2-dichloroethane and the aggregation of BHC1 have been studied by using a two-phase potentiometric titration technique. The experimental data, treated by a general minimizing program, indicate dimerization: 2 BHClright harpoon over left harpoon(BHCl)(2). The equilibrium constant of this reaction was calculated. The extraction of ZnCl(2), CdCl(2) and PbCl(2) from 0.2,0.5, 1.0 and 2.0M HCl, and 1MNaCl by Amberlite LA-2 hydrochloride (BHCl), dissolved in 1,2-dichloroethane, has been studied. The complexes (BHCl)(2)ZnCl(2), (BHCl)(2)CdCl(2) and (BHCl)(2)PbCl(2) were found to exist, irrespective of the composition of the aqueous phase. The formation constant of the first was calculated. 相似文献