主-客体络合物稳定常数的曲线拟合处理

利用曲线拟合法以处理圆二色谱法谱滴定的实验数据,可以给出更为可靠的主－客休络合物的络合稳定常数,与常用的Ｂｅｎｅｓｊ－Ｈｉｌｄｅｂｒａｎｄ方程所得结果比较表明,当络合物稳定常数较大（〉５０００）时,应该使用曲线拟合法。     

1—（5—溴—2—吡啶偶氮）—2—萘酚—6—磺酸与铁（Ⅱ）显色反应的研究及其应用

本研究了１－（５－溴－２－吡啶偶氮）－２－萘酚－６－磺酸（５－Ｂｒ－ＰＡＮ－Ｓ）与铁（Ⅱ）的显色反应，试验表明，在ｐＨ３－１０范围内铁（Ⅱ）与５－Ｂｒ－ＰＡＮ－Ｓ型成稳定的络合物，络合物在５５０ｎｍ和７５０ｎｍ有二个吸收峰，其表现摩尔吸光系数分别为２．３１×１０＾４和１．７７×１０＾４Ｌ．ｍｏｌ＾－＾１．ｃｍ＾－＾１。络合物组成比为铁（Ⅱ）：５－Ｂｒ－ＰＡＮ－Ｓ＝１：２，络合物稳定常数为１．８２     

毛细管电泳环糊精添加剂拆分特布他林对映体的立体选择性研究

分别测定了毛细管区带电泳环糊精手性拆分体系中α,β－环糊精和二甲基、三甲基、羟丙基－β－环糊精与药物对映体特布他林形成包结络合物的稳定常数以及手性拆分过程的热力学函数的变化。数据分析表明,环糊精稳定常数的大小反映了环糊精空腔与分离对象之间的匹配程度。环糊精稳定常数的相对值反映了手性拆分体系的分离能力。两对映体与环糊精所形成包结络合物的Δ（ΔＨ）和Δ（ΔＳ）分别反映了手性拆分过程中立体作用与构象匹配的差异。与甲基化β－环糊精相比,羟丙基－β－环糊精和β－环糊精提供的氢键作用在手性拆分中起着重要作用。     

稀土三元络合物的极谱研究 Ⅱ．Eu（Ⅲ）－Cit－Ap体系稳定常数的测定

本实验用直流极谱法研究了Ｅｕ（Ⅲ）－Ａｐ，Ｅｕ（Ⅲ）－Ｃｉｔ二元体系和Ｅｕ（Ⅲ）－Ｃｉｔ－Ａｐ三元体系的极谱行为，在μ＝０．１（ＮａＮＯ３），ｔ＝２５±０．２℃条件下，电极过程为准可逆；测定了该条件下二元及三元络合物的稳定常数，讨论了三元络合物的有关形成条件。     

阳离子交换法和溶解度法测定溶液中混合型络合物稳定常数的一般处理

离子交换法测定溶液中络合物稳定常数是近十几年来才开始的,溶解度法是测定络合物稳定常数的经典方法之一,均有专论。溶液中混合型络合物稳定常数的测定也是近十几年才开始的,国内有过评介。但用阳离子交换法和溶解度法测定溶液中混合型络合物的稳定常数还未见报导。最近徐光宪等用萃取法以作图外推法测得混合型络合物稳定常数。本文尝试推导了用阳离子交换法和溶解度测定单核双配位体络合物稳定常数的有关公式。     

溶液中络合物的分步稳定常数与配位数间的关系

自从本世纪初布德兰德(Bodlader)等首先测定了铜、银络合物的稳定常数起,迄今已有60余年的历史。目前已经积累了相当数量的各种络合物的稳定常数。但对络合物的分步稳定常数间关系的研究,或对络合物分步稳定常数随配位数增加而改变规律的研究为数不多。雅齐米尔斯基曾指出,络合物分步稳定常数间的关系是一个相当重要的问题。可以说     

稀土三元络合物的极谱研究：II.Eu（Ⅲ）—Cit—Ap体系稳定常数的测定

本实验用直流极谱法研究了Ｅｕ（Ⅲ）－Ａｐ，Ｅｕ（Ⅲ）－Ｃｉｔ二元体系和Ｅｕ（Ⅲ）－Ｃｉｔ－Ａｐ三元体系的极谱行为，在μ＝０．１（ＮａＮＯ３），ｔ＝２５±０．２℃条件下，电极过程为准可逆；测定了该条件下二元及三元络合物的稳定常数，讨论了三元络合物的有关形成条件。     

渐进因子分析—分光光度法测定Fe^3＋—SCN^—络合物的稳定常数

本文利用渐进因子分析与化学平衡相结合的方法迭代求解逐级生成络合物的各级稳定常数，对Ｆｅ＾３＋－ＳＣＮ＾－体系在水溶液及５０％丙酮溶液中的配体浓度－波长的两维双线性吸光度数据矩阵进行处理，求得水溶液中该络合物第一、二级稳定常数为１ｇｋ１＝２．２６，１ｇｋ２＝１．３０。同时该法还可确定各种组分的存在区间及吸收光谱，本文还对丙酮的存在对Ｆｅ＾３＋－ＳＣＮ＾－络合物的影响作了研究，结果表明丙酮，对高配位络     

电位法测定酸解离常数和络合物稳定常数的基本原理和方法(Ⅰ)

应广大读者的要求,本刊开辟了《基础知识讲座》。有机试剂、掩蔽剂等的解离常数和络合物稳定常数对它们的合理使用有很大指导意义,因而愈来愈引起分析化学工作者的重视。不过,测定方法种类繁多,繁简难易相差极大,似乎无所适从。为此,本刊约请北京医学院药学系王夔教授撰写了酸“解离常数和络合物稳定常数的测定”一文,试图向分析化学工作者介绍电位法及光度法测定有关平衡常数的原理和方法。全文分五部分:(Ⅰ)电位法测定酸解离常数和络合物稳定常数的基本原理和方法;(Ⅱ)电位法测定多元酸解离常数;(Ⅲ)电位法测定络合物稳定常数;(Ⅳ)光度法测定解离常数和稳定常数;(Ⅴ)几种特殊情况(易水解金属络合物、混合配体络合物、极稳定络合物等)。本刊将陆续刊载。     

离子交换平衡法测定络合物稳定常数

本文介绍和评价了测定络合物稳定常数的离子交换平衡法,特别注重了腐殖酸络合物稳定常数的测定。     

Spectroscopic study of chloranil charge-transfer complexes of amino acids and related compounds

The absorption maxima, molar absorptivities, infrared spectra, compositions, formation constants, and pH dependence of amino acid—chloranil complexes have been determined with purified chloranil The n-π charge-transfer interaction depends on the presence of an unprotonated amino group; pH 9 is optimal for complex formation, but once formed, the complex is stable in a highly acidic medium and may be quantitatively extracted by hexanol. The molar absorptivities of the chloranil complexes of glycine, iminodiacetic acid, NTA, EDTA, DTPA and TTHA were measured. There is a linear relationship between the logarithm of the molar absorptivities of their chloranil complexes and the number of carboxylic groups in the molecule. There is an inverse linear relationship between the molar absorptivities of chloranil—metal—EDTA complexes and the logarithm of the stability constants of the EDTA chelates. This leads to a new method of determining the stability constants of complexes involving a nitrogen-donating group.     

一个简便的配合物稳定常数测定方法-Al-ECR稳定常数的测定

在配合反应体系中,当某一物种不能获得它单独存在时的吸收光谱,即得不到它的摩尔吸光系数时,测定配合物的稳定常数往往比较困难,有时甚至难以解决。Al-ECR即属于这样的体系,众多通用的饱和法不能使用。我们采用过Ingmen的方法亦未能得出合理的结果(时常出现负值)。我们曾报道利用等色点特性求取三元配合物稳定常数的方法。在这里我们利用溶液不同pH时等色点的特性,测定了Al-ECR体系的稳定常数,方法简便,所得结果比较满意。     

Stability constants and molar absorptivities for complexes of copper(II) with N-methyldiethanolamine, 1,4-bis(2-hydroxypropyl)-2-methylpiperazine, and 2-amino-2-methyl-1-propanol

The stability constants and molar absorptivities of complexes of Cu(2+) with N-methyldiethanolamine, 1,4-bis(2-hydroxypropyl)-2-methylpiperazine, and 2-amino-2-methyl-1-propanol have been determined from spectrophotometric data for very dilute aqueous solutions.     

Cd(II) determination in the presence of aqueous micellar solutions

The equilibrium constants and molar absorptivities for the fast formation of a 1:3 complex between cadmium(II) (Cd(II)) and dithizonate anion, in the presence of cationic and non-ionic surfactants, allowed a simple and fast spectrophotometric determination of total cadmium. Indeed, the molar absorptivities of the Cd(II)-dithizone (Dz) complex formed in the presence of the neutral Triton X-100 and cationic cetyltrimethylammonium bromide (CTAB) surfactants are almost twice the value observed in the standard method and the maxima of absorption are shifted by about 40 nm when compared with the standard method. Clearly, the use of neutral and cationic surfactants promotes a higher value of the molar absorptivities of the complex, resulting in an increase in the sensitivity of the method. Application of the method to the desorption of Cd(II) ions from clays is illustrated.     

Accurate values of stability constant of Ca(2+)-murexide complex

In published reports, the values of stability constants of 1:1 complex of Ca(2+) and the dye ammonium purpurate (murexide) were not determined under controlled conditions and were not properly corrected for the binding of Ca(2+) with ions of buffer used to maintain pH and that of the background electrolyte used to maintain ionic strength. We report the molar absorptivities (epsilon) of murexide at pH 7.0, 7.5, 8.0, as well as the differential molar absorptivities (Deltaepsilon). Using these, we calculate the stability constants of the Ca-murexide complex at pH 5.0, 6.0, 6.5, 7.0, 7.5 and 8.0 at 15, 25 and 35 degrees C and 0.100 M ionic strength using KCl as background electrolyte. No buffer was used and the complication arising from buffer binding is thus avoided. These values are compared with those determined in the presence of buffers that bind metal ions negligibly (Tris at pH 7.5 and 8.0) or whose binding constant to Ca(2+) is reported and therefore can be corrected for (acetate at pH 5.0, Bistris at pH 6.5). Agreement is obtained within errors of measurement. The reported values are not true stability constants but can be used to calculate the concentration of free Ca(2+) ion in a metal-ligand mixture with high precision and accuracy. The effect of K(+) binding to murexide is considered and is found not to alter the calculated value of free calcium concentration in a mixture.     

The influence of dissociation on simultaneous determination of zirconium and hafnium with Xylenol Orange

The molar absorptivities of the zirconium and hafnium Xylenol Orange (1:1) complexes are said to be similar in the acidity range 0.1-2.0M HCl. However, the absorbances obtained for the zirconium-Xylenol Orange complex in the acidity range 0.5-2.0M HCl are much higher than those for the same concentrations of hafnium. The absorbance differences are generally due to the higher stability of the zirconium complex at such acidities. Calculations based on the conditional stability constants of these complexes show the influence of dissociation on the results of simultaneous determination of zirconium and hafnium with Xylenol Orange.     

在二甲基亚砜-水不同配比的溶剂中对硫氰酸钴(Ⅱ)络合物的紫外光度法研究

本文用紫外光度法测定了在不同体积配比的二甲基亚砜-水混合溶剂中,存在不同浓度硫氰酸根时,硫氰酸钴(Ⅱ)络合物的各级摩尔吸光系数和稳定常数及各级络离子的百分组成,表明了上述各项都随着体系中二甲基亚砜浓度的增加而不断增大。     

Spectrophotometric investigation of the reaction of eriochrome cyanin RC and magnesium and aluminium

The reaction of magnesium or aluminium ions with Eriochrome Cyanin RC in alkaline medium leads to formation of a complex of type ML. The molar absorptivities of the complexes are 1.90 +/- 0.14 x 10(3)1. mole(-1).cm(-1) at 570 nm for the magnesium complex and 3.87 +/- 0.04 x 10(4) at 555 nm for the aluminium complex. The conditional stability constants of the complexes were determined at various pH values, and hence the overall formation constants, which were found to be log beta(111) = 8.65 +/- 0.06 for MgOHL, log beta(121) = 22.29 +/- 0.05 for AlH(2)L, log beta(111) = 18.25 +/- 0.14 for AlHL, and log beta(101) = 13.66 +/- 0.01 for AlL.     

Stability constants and molar absorptivities for complexes of chromium(III) and cobalt(II) with 2-pyridylmethanamine

The stability constants and molar absorptivities of complexes of Cr(3+) and Co(2+) with 2-pyridinemethanamine have been determined from spectrophotometric data of very dilute aqueous solutions.     

Purification of xylenol orange by preparative paper chromatography, and examination of its zirconium complex

Preparative paper chromatography is proposed as a suitable method for purification of Xylenol Orange (XO). The last three dissociation constants of pure XO have been determined with the aid of the program SPEKTFOT, the values found being pK(9) = 12.34; pK(8) = 10.66; pK(7) = 6.69 (0.1M KNO(3), 20 +/- 0.5 degrees ). The complexation of zirconium with the purified reagent has been studied and the co-existence of ML and M(2) L complexes proved by use of the program DALSFEK. The following conditional stability constants of the complexes and their molar absorptivities were computed: log beta'(ml) 4.58; log beta'(M(2)L) 11.59; (ML) 2.00 x 10(4); (M(2)L) 9.40x 10(4) l.mole(-1).cm(-1) at 550 nm.