非负矩阵分解法研究三价铁离子与试钛灵形成的多组分体系

采用分光光度法测量三价铁离子与邻苯二酚-3,5-二磺酸钠(试钛灵)的配位数和稳定常数是常见的大学化学教学实验之一。我们发现,随着溶液中三价铁离子与试钛灵配比的改变,配合物的吸收光谱峰位置发生显著位移,推断配位数不唯一。用非负矩阵分解法对系列光谱数据进行分析,获取主要成分的特征光谱和它们的化学配比,结果显示体系中包含两种产物,分别对应一配位和二配位两种形式。然而,教材要求给出一个正整数的配位数,实验设计的合理性值得探讨。     

钛硅复合氧化物局域结构的研究

用XAFS（X-ray absorption fine structure）分析了由溶胶-凝胶、液相浸渍和化学气相沉积等三种方法制备的二氧化钛和二氧化硅复合氧化物的Ti K边结构.结果表明:溶胶-凝胶法制得的复合氯化物中的钛分散很好,液相浸渍法次之,而化学气相沉积法最差.不论哪种方法,随钛含量（或钛硅原子比）的增加,边前特征峰A2降低,钛的第一配位层Ti－O的配位数和键长增加;在复合载体中既有钛中心对称的八面体6配位TiO6的结构也有钛中心对称性差的四面体4配位TiO4或五面体5配位结构,并且随钛含量增加,钛的局域结构越来越接近锐钛矿型二氧化钛.根据XAFS、XRD、IR表征结果,提出了钛硅复合氧化物模型.     

基于硼-二吡咯亚甲基二聚体的红光三价铁离子探针的合成与性质

在硼-二吡咯亚甲基(BOIDPY)的β-β(2/6)位偶联得到一种新型的红光二聚体BODIPY荧光探针1,该探针可以发生高效的能量转移,假-斯托克斯位移可以达到222 nm。探针1能够专一性地识别三价铁离子,不受其它常见金属离子的干扰,可以作为检测三价铁离子的高选择性的探针。     

基于硼-二吡咯亚甲基二聚体的红光三价铁离子探针的合成与性质（英文）

在硼-二吡咯亚甲基(BOIDPY)的β-β(2/6)位偶联得到一种新型的红光二聚体BODIPY荧光探针1,该探针可以发生高效的能量转移,假-斯托克斯位移可以达到222 nm。探针1能够专一性地识别三价铁离子,不受其它常见金属离子的干扰,可以作为检测三价铁离子的高选择性的探针。     

基于硼-二吡咯亚甲基二聚体的红光三价铁离子探针的合成与性质

在硼-二吡咯亚甲基(BOIDPY)的β-β(2/6)位偶联得到一种新型的红光二聚体BODIPY荧光探针1,该探针可以发生高效的能量转移,假斯托克斯位移可以达到222nm.探针1能够专一性地识别三价铁离子,不受其它常见金属离子的干扰,可以作为检测三价铁离子的高选择性的探针.     

Al(Ⅲ)-槲皮素配合物的光谱分析

采用UV和IR分析手段,研究在甲醇溶剂酸性和中性条件下,槲皮素(3,3,′4,′5,7-五羟基黄酮)与A l(Ⅲ)形成配合物的构型、反应配比及在配位反应过程中配体分子中各个配位点的配位能力大小及优先配位的顺序。实验结果表明:在酸性介质中,槲皮素与A l(Ⅲ)所形成配合物的反应配比为A l(Ⅲ)∶Q=1∶1,其配位点为3-羟基-4-酮,配位构型中心为A l(Ⅲ)与一个槲皮素分子形成五元环四配位的配合物。在中性介质中发生两步配位反应,第一步配位反应发生在3-羟基-4-酮配位点其反应配比为1∶2,配位构型为中心A l(Ⅲ)与两个槲皮素分子形成两个五元环之间四配位的配合物;第二步配位反应发生在3,′4′-二羟基配位点其反应配比为2∶1,两个A l(Ⅲ)离子分别在上述两个配位点与一个槲皮素分子形成五元环四配位构型的配合物。     

以四溴化钛为催化剂的丁二烯定向聚合

本工作研究了四溴化钛与三异丁基铝、三乙基铝或丁基锂组成的催化剂对丁二烯的聚合。结果指出,在三异丁基铝与四溴化钛的系统中以苯为溶剂,有两个铝钛比值呈现最大活性。随铝钛比增加,产物的凝胶及分子量下降,可溶部分顺式-1,4含量亦随之减少。聚合活性以单体先与铝混合较先与钛混合为高。聚合温度降低时最大活性向铝钛比大的区域移动。以庚烷代替苯作为溶剂时,聚合速度降低,仅有一个铝钛比呈现最大活性,产物分子量及凝胶均较低,可溶部分顺式-1,4含量亦较低。如以三乙基铝代替三异丁基铝,则仍有两个铝钛比值呈现最大活性。聚合温度较低时,三乙基铝与四溴化钴的催化活性较三异丁基铝为高。二个系统的大部分产物类似,凝胶较多,可溶部分顺式-1,4含量在70％以下。利用丁基锂与四溴化钛组合的催化系统聚合丁二烯,可得顺式-1,4含量达90％以上的产物。活性范围为锂钛克分子此1.5—2.5。顺式-1,4含量随锂钛比增大而降低。本工作还比较了上述三种催化系统生成低价钛的情况。结果指出,在金属烷基物与四溴化钛的克分子比小于2时,三价钛均随克分子比增大而增大,克分子比大于2时,丁基锂的还原能力随克分子比增加而减少。在其他二种系统中则低价钛继续增加。有意义的是丁基锂-四溴化钛系统中聚合活性正好在三价钛最高     

紫外拉曼光谱研究FeAlPO_4-5分子筛的合成机理

利用紫外共振拉曼光谱和紫外-可见漫反射光谱对不同铁含量的 FeAlPO4-5 分子筛进行了研究. 结果表明, FeAlPO4-5 分子筛的骨架铁有 4 个特征的拉曼谱峰, 分别位于 630, 1060, 1140 和 1210 cm?1. 当凝胶中 Al/Fe 比小于 380 时, 只有一部分铁离子可以进入分子筛形成四配位的骨架铁物种; 而另一部分则以骨架外六配位的铁物种存在, 其特征拉曼谱峰位于 285 cm?1. 结合紫外拉曼光谱、紫外-可见漫反射光谱和 X 射线衍射研究了 Al/Fe 比为 760 时 FeAlPO4-5 分子筛的晶化过程. 结果发现, 在分子筛晶化前, 铁物种以六配位的形式存在, 它为分子筛前体中的一维链状磷酸铝添加了一个惰性端基, 六配位的 Fe-O 键不利于它与其它磷酸铝物种发生反应; 当分子筛开始晶化时, 带有铁离子端基的磷酸铝链与其它磷酸铝链进一步反应形成分子筛骨架. 同时, 六配位的铁离子和邻近的磷酸铝物种反应转化为四配位的骨架铁物种.     

立体化学刚性的七配位环戊二烯基三(二苄基二硫代氨基甲酸)钛、锆、铪配合物的合成和性质

二烷基二硫代氨基甲酸基作为良好的双齿配体较易与过渡金属生成高配位的配合物,含有环戊二烯基的高配位钛、锆、铪配合物的研究相继出现,这类七配位、18-电子构型的配合物是立体化学刚性,具有独特的光谱性质和结构行为。选择钛、锆和铪二茂二氯化物与三当量的二苄基二硫代氨基甲酸钠反应合成了五种未见报道的七配位配合物,讨论了产物的光谱性质和配位结构。     

亚硝酸钠的毒害及解救

亚硝酸钠是一种用途广泛,但人体摄入过量后能引起严重毒害的物质。亚硝酸钠有强氧化性,能使体内正常的血红蛋白中的两价铁离子氧化成三价铁离子,从而使血红蛋白失去可逆性运送氧气和交换二氧化碳的能力。亚硝酸钠中毒后常出现严重缺氧症状。急救时一般采用洗胃、注射亚甲兰或Vc等措施。这里同样利用氧化还原的原理,即这些药物本身极易氧化,而使三价铁离子还原成两价铁离子,从而恢复血红蛋白的正常生理功能。当然,严重时则需输血,以补充新鲜的血红蛋白。     

Gemischt-Ligand-Komplexe von Eisen(III) mit Brenzkatechin-3,5- disulfonsäure (Tiron) und Thiocyanat in wäßriger Lösung

Mixed-Ligand complexes of Iron(III) with Pyrocatechol-3,5- disulfonie Acid (Tiron) and Thiocyanate in Aqueous Solution In the system iron(III), tiron, thiocyanate two ternary complexes could be detected in acid solution. By spectrophotometric measurements we found the species [Fe(Tiron)(SCN)(H₂O)₃]^2? and [Fe(Tiron)₂(SCN)(H₂O)]^6?. The formation and the optical properties (^λmax,^? max) are discussed.     

Fe(III)与2,3-二羟基苯磺酸钠配位反应的动力学研究

[H⁺]在0.01～0.70 mol•L^－1范围内, 离子强度为1.00 mol•L^－1, [Fe(III)]>>[配体]、[H⁺]>>[配体]的条件下, 研究了Fe(III)与2,3-二羟基苯磺酸钠(Tiron)的配位反应. 发现当[H⁺]≤3.00×10^－2 mol•L^－1时, [Fe(III)]²对反应速率有明显的贡献. 求得了相关反应的动力学参数, 从而揭示了FeOH²⁺和与Tiron配位的解离反应途径及的缔合反应机制, 并提出了该配位反应的可能机理.     

Structural studies of uranium and thorium complexes with 4,5-dihydroxy-3,5-benzenesdisulfonate (Tiron) at low and neutral pH by X-ray absorption spectroscopy

We have determined the structure of uranyl, UO(2)(2+), and Th(4+) complexes formed in aqueous solution with 4,5-dihydroxy-3,5-benzenedisulfonate (Tiron) as function of pH and concentration. At equimolar concentrations of 0.05 M UO(2)(2+) and Tiron, the predominant species was found to be aqueous uranyl at pH = 2.0. At pH = 6.0, the formation of a 3:3 UO(2)(2+):Tiron trimer (proposed in earlier studies) was observed. In this structure, bidentate catecholate complexation to Tiron as well as oxygen bridging between uranyl units is detected. Th(4+) structural changes were observed both as a function of pH and Th:L (L = Tiron) ratio. At Th:L = 1:1 and pH = 1.4, a monomeric complex is observed with each Th center complexing monodentate to approximately 2 sulfonate functional groups. At pH 4.0 similar sulfonate ligation is observed along with oligomer formation. At pH 6.0 thorium hydrolysis products are detected, with little evidence for inner-sphere Tiron coordination. When the Th:L is changed to 1:2 at pH = 6.0, a stable oligomeric complex is formed that dominates the speciation for Th:L ratios up to 1:5. This complex is characterized by bidentate catechol and monodentate sulfonate ligation to Tiron along with oxygen bridging between Th(4+) atoms and is consistent with the formation of the 2:3 Th:L polymeric species proposed from earlier work. At a Th:L ratio of 1:10, Th(4+) complexation is dominated by bidentate catechol ligation and the formation of a monomeric Th(Tiron)(x) species, where x > or = 2.     

Die Reaktion von Eisen(III) mit Brenzkatechin-3,5-disulfonsäure (Tiron) und Äthylendiamintetraessigsäure

The Reaction of Iron(III) with Catechol-3,5-Disulphonic Acid (Tiron) and Ethylene Diamine-Tetracetic Acid In the system iron(III)-Tiron-EDTA a ternary chelate could be detected besides the well known complexes in a weak acid solution. By means of spectro-photometric measurements under various conditions (concentration of ligands) we found [FeHYL]^4? with λ_max = 555 nm und ε₅₅₅ = 2500 l · mol^?1 · cm^?1. The formation of the ternary chelate is an inner-complex reaction of displacing, in which donor atoms of the EDTA in FeY^? are replaced by Tiron. By graphic methods the equilibrium constants could be calculated from the measurements.     

Spectrofluorimetric determination of copper(II) by its static quenching effect on the fluorescence of 4,5-dihydroxy-1,3-benzenedisulfonic acid

A spectrofluorimetric method has been developed for the determination of trace Cu(II) in real samples with 4,5-dihydroxy-l,3-benzenedisulfonic acid (Tiron) as a fluorimetric reporter. Tiron is very soluble in water and is a good fluorimetric reagent. However, as Tiron was complexed with Cu(II), the fluorescence intensity decreased proportionally to the concentration of Cu(II) by a static quenching effect. The excitation wavelength and the fluorescence wavelength of Tiron were 294 and 350 nm, respectively, as it was caused by a quenching effect from Cu(II) at pH 8.0. The highest sensitivity was shown at Tiron concentration of 5.0x10(-5) M. To enhance the quenching effect, the Cu(II)-Tiron complex solution was heated up to 80 degrees C for 90 min. As for Cu(II), the interference by Co(II) was very serious, which was eliminated by oxalate ion. The linear response to Cu(II) was shown at the concentration range between 5.0x10(-7) and 1.0x10(-5) M. With this proposed method, the detection limit of Cu(II) was 3.83(+/-0.09)x10(-7) M. Recoveries of Cu(II) in the diluted brass samples and the stream water samples were almost 100%. Based on results from the experiment, this proposed technique could be applied to the practical determination of Cu(II) in real samples.     

Spectrofluorimetric determination of terbium as its ternary complex with edta and tiron Compositional studies,optimization of fluorescence output and conversion to a flow system

The spectrofluorimetric determination of terbium(III) as its ternary complex with EDTA and Tiron was studied further with regard to composition of the complex and the procedure was optimized by a simplex method. The results suggest a 1:1 molar ratio of terbium to Tiron for the ternary complex. The optimization study indicated that the three chosen variables (pH, and EDTA and Tiron concentration) are not interactive. The method was converted for use in a segmented-flow system with basic Technicon units and a spectrophotofluorimeter as detector. This procedure is satisfactory for the determination of terbium(III) in the range 0.03–0.24 μg ml^?1 at a sampling rate of 30 h^?1. Results were satisfactory for the determination of terbium in lanthanide oxides, mixed oxides, the mineral bastnasite and a green phosphor (Gd_0.96 Ce_0.02 Tb_0.02 F₃).     

Lanthanide complexes based on a 1,7-diaza-12-crown-4 platform containing picolinate pendants: a new structural entry for the design of magnetic resonance imaging contrast agents

We have synthesized a new macrocyclic ligand, N,N'-Bis[(6-carboxy-2-pyridyl)methyl]-1,7-diaza-12-crown-4 (H 2bp12c4), designed for complexation of lanthanide ions in aqueous solution. The X-ray crystal structure of the Gd (III) complex shows that the metal ion is directly bound to the eight donor atoms of the bp12c4 ligand, the ninth coordination site being occupied by an oxygen atom of a carboxylate group of a neighboring [Gd(bp12c4)] (+) unit, while the structure of the Lu (III) analogue shows the metal ion being only eight-coordinate. The hydration numbers obtained from luminescence lifetime measurements in aqueous solution of the Eu (III) and Tb (III) complexes suggest an equilibrium in aqueous solution between a dihydrated ( q = 2), ten-coordinate and a monohydrated ( q = 1), nine-coordinate species. This has been confirmed by a variable temperature UV-vis spectrophotometric study on the Eu (III) complex. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by theoretical calculations performed at the DFT (B3LYP) level. The results indicate that the change in hydration number occurring around the middle of the lanthanide series is accompanied by a change in the conformation adopted by the complexes in solution [Delta(lambdalambdalambdalambda) for q = 2 and Lambda(deltalambdadeltalambda) for q = 1]. The structure calculated for the Yb (III) complex (Lambda(deltalambdadeltalambda)) is in good agreement with the experimental structure in solution, as demonstrated by the analysis of the Yb (III)-induced paramagnetic (1)H shifts.     

Reversed phase HPLC determination of titanium(IV) and iron(III) with sodium 1,2-dihydroxybenzene-3,5-disulfonic acid

A highly sensitive method has been developed for the determination of titanium(IV) and iron(III) by ion-pair reversed phase liquid chromatography using sodium 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) as a precolumn chelating reagent. The metal - Tiron chelates were separated on a C₁₈ (ODS) column; the mobile phase was a 2:8 (v/v) mixture of acetonitrile and acetate buffer (0.04 mol/L, pH 6.2) containing 2.0 × 10^?3 mol/L Tiron, 0.04 mol/L tetrabutylammonium bromide, and 0.1 mol/L potassium nitrate. The detection limits for titanium(IV) and iron(III) are 0.5 and 2.0 μg/L, respectively. The method has been applied to the simultaneous determination of titanium(IV) and iron(III) in river water samples and has furnished highly precise results.     

Investigation of the extraction complexes of light lanthanides(III) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid by EXAFS,IR, and MS in comparison with the americium(III) complex

The structure of the extraction complexes of light lanthanides (La(III), Nd(III), Eu(III)) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HBTMPDTP) have been characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), IR, and MS; the IR spectrum of the extraction complex of (241)Am with HBTMPDTP has been studied too. The molecular formula of the extraction complexes of lanthanides is deduced to be HML(4).H(2)O (M = La, Nd, Eu; L = anion of HBTMPDTP). The coordination number of Ln(III) in the complexes is 8; the coordinated donor atoms are 7 sulfur atoms from 4 HBTMDTP molecules and 1 O atom from a hydrated water molecule. With the increase of the atomic number of Ln, the coordination bond lengths of Ln-O and Ln-S decrease in the complexes. For La(III), Nd(III), and Eu(III), the coordination bond lengths of Ln-O are 2.70, 2.56, and 2.50, respectively, the coordination bond lengths of Ln-S are 3.01, 2.91, and 2.84, respectively, and the average distances between Ln and P atoms are 3.60, 3.53, and 3.46, respectively. The structure of the extraction complexes of Ln(III) with HBTMDTP is different from that of the Am(III) extraction complex. The results of IR show that there is no water coordinated with Am in the extraction complex. The molecular formula of the complex of Am(III) is deduced as being HAmL(4), and there are 8 S atoms from 4 HBTMPDTP molecules coordinated with Am. Composition and structure differences of the extraction complexes may be one of the most most important factors affecting the excellent selectivity of HBTMPDTP for Am(III) over Ln(III).     

Stabilities of Scandium(III)- and Yttrium(III)-Tiron Chelates and their hydrolytic behavior

The interactions of Sc³⁺ and Y³⁺ ions with disodium 1,2-dihydroxybenzene-3,5-disulfonate (Na₂H₂L, where H₂L_2- = Tiron) were investigated in aqueous solution by means of potentiometric and spectroscopic methods. The coordination of Tiron to Sc³⁺ and Y³⁺ takes place through two phenolic oxygen atoms of catecholate ion in different stoichiometries. Thus, the binding of Tiron to Sc³⁺ occurs either in 1 : 1 or 1 : 2 molar ratios; they have resulted by the formation of [ScL]^- and [ScL₂]^5- type complexes, respectively. On the other hand, Y³⁺ ion behaves like Th⁴⁺ and Ln³⁺ ions toward Tiron. It forms [YL]^-type complex in 1 : 1 molar ratio; but in 1 : 2 or in higher molar ratios, only unique [Y₂L₃]^6- type complex formation takes place. The formation constants of [ScL]^-, [ScL₂]^5-, [YL]^-, and [Y₂L₃]^6- complexes were determined by analysis of the potentiometric data in ionic medium of 0.1 M KNO₃ or NaClO₄ at 25°C. The hydrolytic reactions of Sc(III) and Y(III) complexes with Tiron were determined from potentiometric data and the formation constants of [ScL(OH)]^2- and [YL(OH)]^2- were also calculated.From Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 62–68.Original English Text Copyright © 2005 by Aydin, Türkel, Özer.