Kinetics and Mechanism of Iridium（Ⅲ）-Catalyzed Oxidation of Ethanol Amine by Cerium（ Ⅳ ） in Sulfuric Acid Media

In this study, the kinetics and mechanism of the iridium(Ⅲ)-catalyzed oxidation of ethanol amine(EAN) by cerium(Ⅳ) in a sulfuric acid medium was investigated using titrimetric technique of redox in a temperature range of 298—313 K. It was found that the reaction is of first order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EAN. It was also found that the pseudo-first-order([EAN][Ce(Ⅳ)]) rate constant kobs decreases with the increase of [H ] and [HSO-4]. Under the protection of nitrogen gas, the reaction system can initiate the polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a suitable mechanism was proposed. From the dependence of kobs on the concentration of hydrogen sulfate, Ce(SO4)2 was found to be the kinetically active species. The rate constants of the rate-determining step together with the activation parameters were evaluated.     

Kinetics and Mechanism of the Oxidation of Glycol by Dihydroxyditelluratoargentate(Ⅲ) with Spectrophotometry

The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16.6-40 ℃).The first-order rates with respect to glycol and Ag(Ⅲ) were all found.The rates increased with the increase in [OH-] and decreased with the increase in [TeO2-4].No effect was found with the addition of KNO3 and no free radical was detected.In view of this,the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can explain all experimental observations.Activation parameters of the rate-determining step and constants are evaluated.     

Kinetics and Mechanism of Oxidation of Glycol by Dihydroxydiperiodatonickelate ( Ⅳ )Complex in Aqueous Alkaline Medium

The kinetics of oxidation of glycol by dihydroxydiperiodato nickelate ( Ⅳ) complex (DDN) was studied by spectrophotometry in aqueous alkaline medium in a temperature range of 25-40℃. The reaction was found to be first order with respect to Ni( Ⅳ ) and also to be first order with respect to glycol. The rate increases with the increase in [OH ] and decreases with the increase in [IO-4], showing that dihydroxymonoperiodatonickelate ( Ⅳ )(DMN) is the reactive species of oxidant. Salt effect indicated that the reaction is of ion-dipole type. No free radical was detected. A mechanism of an inner-sphere two-electron transfer reaction involving a preequilibrium between DDN and DMN is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate-determing step and the equilibrium constants were calculated.     

Solid-state electrochemiluminescence of a novel iridium(Ⅲ) complex

The sofid-state ECL behavior of a water-insoluble bis-cyclometalated (pq)2Ir(N-phMA) complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/(pq)2Ir(N-phMA) film, MWNTs/Ru(bpy)32+ film and (pq)2Ir(N-phMA) directly modified glassy carbon electrode were fabricated; only the MWNTs/(pq)2Ir(N-phMA) film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.     

Studies of Unusual Oxidation States of Transition Metals Ⅱ——Kinetics and Mechanism of Oxidation of Pyruvate by Diperiodatoargentate (Ⅲ)Ion

The kinetics of oxidation of pyruvate by diperiodatoargentate( III) ion (DPA) has been studied spec-trophotometrically in alkaline medium. It was found that the reaction order with respect to both DPA and pyruvate is unity and the rate equation can be expressed asThe rate increases with the increase in [OH ] and decreases with the increase in [periodate]. There is a positive ionic strength effect in this reaction system. A mechanism has been proposed to explain the experimental results. The observed activation parameters are presented.     

Kinetics and Mechanism of Oxidation of Lactic Acid by Dihydroxyditelluratoargentate（Ⅲ）in Alkaline Medium

The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ）[abbreviated as DDA of Ag(Ⅲ）]anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature range of 25-40℃.The order of the redox reaction of lactic acid and DDA was found to be first-order.The rates increased with the increase in [OH^-]and decreased with the increase in [tellurate].No free radical was detected.In the view of this the dihydroxymonotelluratoargentate(Ⅲ）species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can be used to explain all the experimenttal results.The activation parameters(25℃）and the rate constants of the rate-determining step along with the preequilibrium constants at different temperatures were evaluated.     

Ag(Ⅰ)、Au(Ⅲ)、Pt(Ⅳ)离子与DNA相互作用的光谱研究

本文用中药小檗碱作为探针分子,在0.01mol·L^-1醋酸-醋酸钠缓冲体系中,用荧光和紫外-可见吸收光谱研究了贵金属离子Ag(Ⅰ)、Au(Ⅲ)、Pt(Ⅳ)与DNA的相互作用。在三种贵金属离子中,Au(Ⅲ)、Pt(Ⅳ)离子对小檗碱-DNA体系均具有明显的荧光猝灭作用,而Ag(Ⅰ)离子对该体系有强烈的荧光敏化作用。分别求出了三种贵金属离子与DNA的结合常数。三种贵金属离子与DNA结合能力的强弱顺序依次为:Au(Ⅲ) >Ag(Ⅰ) >Pt(Ⅳ)。探讨了三种贵金属离子与DNA的作用机理及导致结合力不同的原因。     

Thermal Decomposition Kinetics and Mechanism of Tb(Ⅲ) m-Methylbenzoate Complex with 1,10-Phenanthroline in Static Air Atmosphere

IntroductionThe rare- earth carboxylic acid complexes havemany special structures and interesting spectro-scopic properties,which are of great interestin ex-traction,separation,germicide preparation,catal-ysis,luminescence and functional material prepara-tion.The preparation,crystal structure,fluores-cence spectroscopy and thermal properties of somerare- earth carboxylic acid complexes have beenstudied[1— 8] . In this work,on the basis of thestructural and fluorescence spectroscopicresearches…     

Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6]

A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).     

Synthesis and Characterization of 2-Decyl-DTPA and Its Gd(Ⅲ) Chelate

The present paper covers the synthesis and the characterization of ligand 2-decyl-3, 6, 9-tris(carboxymethyl)-3,6,9-triazaundecan-1,11-dioic acid, H5L, and its Gd(Ⅲ) chelate. The protonation constants for H5L(lgKHi=10.90, 8.50, 4.55, 2.92, 2.20) and the stability constant for GdL2- (lgKGdL2-=22.80) were determined by means of potentiometric titration. They are similar to the corresponding values of DTPA and Gd-DTPA, respectively. The results obtained show that the basicity of the ligand and the stability constant of its Gd(Ⅲ) chelate are not obviously altered after the introduction of a linear chain decyl group into the terminal acetic acid residue of DTPA. The Gd(Ⅲ) chelate may be a potential contrast agent with liver-specificity for magnetic resonance imaging(MRI).     

Study on the Biomimetic Oxidation Catalyzed by the Model Compound of Cytochrome P-450(VI)——The Influence of Substituent x in T(x-p)PMn(Ⅲ)Cl on the Hydroxylation of Alkane

The influence of monosubstitution at phonyl rings in a series of T(x-P) PMn (Ⅲ)Cl (x = o , m , p-CH3, CH3O, Cl, Br, I, NO , o-NH2, p-(CH3)3C) on the biomimetic catalytic hydroxylation and chlorizaiton of cyclohexane with PhIO was studied. The yields of cyclohexanol and chlorocyclohexane increased with the electron-withdrawing ability of the substituent in this manganese complex. The fair linear correlations between the yields of cyclohexanol and para or ortho substituent constant are presented as:logYx/YH = 0.310p+0.03, logyx/YCH3 = 0.61σ0.07Es+0.05, But there are no linear correlations between the yields of chloro-cyclohexane and either para, ortho or meta substituent constants.     

Antituberculosis and cytotoxic activities of triorganotin(Ⅳ) complexes

Five triorganotin（Ⅳ）（1-5） complexes of cinnamic acid.（Z）-2-acetamido-3-phenylacrylic acid,3-methylbut-2-enoic acid,and 2,2-diphenylacetic acid have been synthesized and characterized by ¹H-¹³C-¹¹⁹Sn NMR,UV,and IR.The spectroscopic investigation demonstrated that the carboxylate group acts as a monodentate ligand in triorganotin（IV） compounds.Five triorganotin（Ⅳ） complexes were screened against the log phase culture of Mycobacterium tuberculosis H37Rv by colorimetric method using XTT dye as growth indicator.The MICs were found to be 0.08 and 1.25μg/mL.     

Synthesis and Crystal Structure of a Cyano-bridged Bimetallic Complex:[NdFe(CN)_6(DMF)_4(H_2O)_3]H_2O

1 INTRODUCTION In recent years, cyano-bridged heterometallic coordination compounds have inspired remarkable attention due to their rich and interesting structures and magnetic behaviors. However, these studies were mainly focused on the transition metals. Although several unusual cyanide bridging lanthanide-transition metal complexes have been re- ported[1～6], this field continuously possesses tre- mendous researching potentialities. As regardsPrussian Blue lanthanide complex, divers…     

铬(Ⅲ)离子催化铈(Ⅳ)离子氧化四氢糠醇的反应动力学及机理

在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在铬(Ⅲ)离子催化作用下,于25～40℃区间氧化四氢糠醇的反应动力学.结果表明反应对铈(Ⅳ)和四氢糠醇均为一级.准一级速率常数kobs随催化剂[Cr(Ⅲ)]增加而增大,亦随[H+]增加而增大,而随[HSO-4]增加而减小.在氮气保护下,反应不能引发丙烯酰胺聚合,说明在反应中没有自由基产生.提出了催化剂、底物和氧化剂间生成双核加合物的反应机理.通过kobs与HSO-4的依赖关系,并结合Ce(Ⅳ)在溶液中的平衡,找到了本反应体系的动力学活性物种是Ce(SO4)2.还计算出一些速率常数及相应的活化参数.     

Syntheses and Characterization of Pentacoordinate Organotin (Ⅳ) Complexes

Ten novel pentacoordinate organo-tin complexes were prepared and characterized. Singlecrystal structure determination by X-diffraction was made.     

Studies on Insoluble Species of Gd(Ⅲ)in Human Blood Plasma by Computer Simulation

The insoluble species of Gd ( Ⅲ ) in human blood plasma were investigated by computer simulation. The distribution of the Gd(Ⅲ ) species was obtained. It was found that most of the Gd( Ⅲ ) ions were bound to phosphate to form precipitate GdPO4 at the concentration of 1. 000 10-7 mol/L and when the concentration of the Gd (Ⅲ ) increased to 3. 750 X 10-4 mol/L, in excess of the concentration of phosphate, the Gd ( Ⅲ ) ions were bound to carbonate to form another kind of precipitate, Gd2(CO3)3.     

An ion-imprinted polymer supported by attapulgite with a chitosan incorporated sol-gel process for selective separation of Ce(Ⅲ)

The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the synthesis of a new attapulgitesupported polymer for selective separation of Ce(Ⅲ) from aqueous solution.The imprinting mechanism of prepared ion-imprinted polymer were discussed with the Characteristics of FT-IR and SEM.Results from the experiments of adsorption capacity and selectivity suggested that ion-imprinted polymer offered a fast kinetics for the adsorption of Ce(Ⅲ) under the optimum conditions. Its m...     

Synthesis of Five-coordinated Anionic Tin(Ⅳ) Complexes and Crystal Structure of [(I-Pr)2NH2][PhSn(μ2-SCH2COO)2]

Four new five-coordinated anionic tin(Ⅳ) complexes with a form of [RnNH4-n][PhSn(μ2-SCH2COO)2] were synthesized via the reaction of mercaptoacetic acid with phenyltin trichloride in the presence of different organic bases and characterized by means of IR, 1H NMR and MS spectroscopies. The crystal structure of [(i-Pr)2NH2][PhSn(μ2-SCH2COO)2] was determined by X-ray diffraction. In the crystal structure, the tin atom is five-coordinated and exists in trigonal bipyramid geometry with cell parameters a=1.1766(11) nm, b=1.3144(14) nm, c=1.3336(15) nm, β=90° and Z=4.