Preconcentration by Using Microcrystalline Phenolphthalein for Determining Trace Molybdenum(Ⅵ) in Water by GFAAS

Introduction Molybdenum(Ⅵ) is a biologically essential trace element and its role in an extremely wide variety of systems has been reported. Most common methods often fail to determine trace Mo(Ⅵ) in the analysis of molybdenum-containing samples, due to limitations such as inadequate detection limits and matrix interference, which make the direct determinations impossible.     

Study on Preconcentration of Trace Copper Using Microcrystalline Triphenylmethane Loaded with Malachite Green

The paper describes a novel method for copper preconcentration using microcrystalline triphenylmethane loaded with malachite green prior to the determination by the flame atomic absorption spectrometry （FAAS）. Under the optimum conditions, Cu（Ⅱ） can be totally adsorbed on the surface of microcrystalline triphenylmethane, and completely separated from Pb（Ⅱ）, Cd（Ⅱ）, Co（Ⅱ）, Cr（Ⅲ）, Ni（Ⅱ）, Mn（Ⅱ）, Fe（Ⅲ） and Al（Ⅲ） by controlling acidity. The preconcentration factor of this proposed method is 200. The recovery is in a range of 97.5%-105%. The relative standard deviation （RSD） is not beyond 3.0%. The proposed method has been successfully applied to the determination of trace copper in various water samples with satisfactory results.     

Preconcentration and Determination of Trace Amounts of Heavy Metals in Water Samples Using Membrane Disk and Flame Atomic Absorption Spectrometry

A fast and simple method for preconcentration of Ni^2＋, Cd^2＋, Pb^2＋, Zn^2＋, Cu^2＋ and Co^2＋ from natural water samples was developed. The metal ions were complexed with sodium diethyldithiocarbamate （Na-DDTC）, then adsorbed onto octadecyl silica membrane disk, recovered and determined by FAAS. Extraction efficiency, influence of sample volume and eluent flow rates, effects of pH, amount of Na-DDTC, nature and amount of eluent for elution of metal ions from membrane disk, break through volume and limit of detection have been evaluated. The effect of foreign ions on the percent recovery of heavy metal ions has also been studied. The limit of detection of the proposed method for Ni^2＋, Cd^2＋, Pb^2＋, Zn^2＋, Cu^2＋ and Co^2＋was found to be 2.03, 0.47, 3.13, 0.44, 1.24 and 2.05 ng·mL^-1, respectively. The proposed （DDTC） method has been successfully applied to the recovery and determination of heavy metal ions in different water samples.     

Solvent Effects on Complexation of Molybdenum（Ⅵ） with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H^＋＋ Mo（Ⅵ）＋nitrilotriacetic acid and H^＋ ＋ nitrilotriacetic acid have been determined in aqueous solutions of propanol at 25 ℃ and constant ionic strength 0.1 molodm^-3 sodium perchlorate. The composition of the complex was determined by the continuous variation method. It was shown that molybdenum（Ⅵ） forms a mononuclear 1 ： 1 complex with nitrilotriacetic acid of the type MoO3L^-3 at -lg[H^＋] =5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft＇s parameters. Linear relationships were observed when lg Ks was plotted versusp. Finally, the results were discussed in terms of the effect of solvent on complexation.     

Synthesis and Characterization of a One- dimensional Molybdenum Oxide （H2enMe）[Mo3O10]

A hybrid organic-inorganic material (H2enMe)[Mo3O10] (C3H12Mo3N2O10, Mr = 523.97) has been synthesized under hydrothermal conditions and its crystal structure was determined by X-ray diffraction. It crystallizes in the orthorhombic system, space group Pnma with a = 12.430(2), b = 7.6089(12), c = 11.9553(19) , V = 1130.7(3) 3, Dc = 3.078 g/cm3, Z = 4, μ(MoKa) = 3.328 mm1, F(000) = 1000, the final R = 0.0256 and wR = 0.0716 for 1314 observed reflections with I > 2σ(I). A total of 11780 reflections were measured and 1325 were unique (Rint = 0.0244). It consists of infinite one-dimensional edge-sharing MoO6 octahedral chains with [Mo3O10]2 moieties. The protonated diaminopropane cations are located between the chains and linked to the oxygen atoms of the inorganic skeletal backbones by hydrogen bonds. It is indicated that the as-synthesized compound displays photochromic property in the solid state.     

Synthesis,Structural Characterization and Reactivity of Two New Triangular Molybdenum Cluster Compounds：Mo3T37—[S2CN（CH2CH2OH）2]3I and Mo3Te4Y3[S2P（^iPrO）2]3I（Y3=1.43Te＋1.57S）

Two triangular molybdenum‐tellurium clusters, Mo₃Te₇‐[S₂CN (CH₂CH₂OH₂]₃I (1) and Mo₃Te₄Y₃[S₂P(ⁱPrO)₂]₃I (Y₃ = 1. 43Te+ 1.57S) (2), were obtained from the reaction of K · HOdtc [HOdtc = S₂CN(CH₂CH₂OH)₂] or K·ⁱPr₂dtp (ⁱPr₂dtp = S₂P[OCH(CH₃)₂]₂) with a mixed product of elements Mo, Te(S) and I₂ at high temperature. The structures of the two compounds were determined by X‐ray crystallography study. Crystal data are, (1): monoclinic, P2₁/n, a = 1.6256(3), b = 1.3264(2), c = 1.8808(4) nm, β=96.923°, V = 4.025.9 (14) nm³, D_cal = 3.050g·cm‐³, Z = 4, and (2): monoclinic, P2₁/n, a = 1.4564(2), b = 2.3917(4), c = 1.5094(3) nm, β = 114.35(2)°, V = 4.0259(14) nm³, D_cal = 2.449 g·cm^?3 and Z = 4. Single crystal analyses show that 1 consists of discrete Mo₃Te₇[S₂CN(CH₂CH₂OH)₂]₃I connected into three‐dimensional framework via hydrogen bonds, while 2 forms a linear chain via Te(S)—I interaction.     

含有不同配位阳离子的四帽Keggin结构砷钼钒酸盐[Co（en）3][Co（en）2（H2O2]2·[Mo4^ⅤMo4^ⅥV8^ⅣO40（AsO4）]的合成与结构

多金属氧酸盐在催化、医药和材料等方面的应用越来越成为无机化学研究的热点[1～5].水热合成技术在合成多核金属氧酸盐中有独特的优点.在众多的钼钒酸盐中,只有几种双帽及四帽Keggin结构被合成出来[6～13].本文报道一种含有不同配位阳离子的四帽Keggin结构砷钼钒酸盐[Co(en)3]·[Co(en)2(H2O)2]2·[Mov4MoⅥ4VⅣ8O40(AsO4)]的合成与结构.该化合物的结构是由不同的阳离子--1个[Co(en)3]3+和2个[Co(en)2(H2O)2]2+及簇阴离子[Mov4MoⅥ4VⅣ8O40(AsO4)]5-构成的.[Mo8V8O40(AsO4)]5-簇阴离子具有四帽"Keggin"结构,两对V原子位于4个"双帽"位置,簇笼中央是1个{AsO4}四面体.     

Study on the Quantitative Structure-toxicity Relationships for the Selected Esters by Using Molecular Electronegativity Interaction Vector （MEIV）

The molecular electronegativity interaction vector (MEIV) was used to describe the molecular structure of 30 selected esters. Two excellent QSTR models were built up by using multiple linear regression (MLR) and partial least-squares regression (PLS). The correlation coefficients (R) of the two models were 0.945 and 0.941, respectively. The models were evaluated by performing the cross validation with the leave-one-out (LOO) procedure. The cross-verification correlation coefficients (RCV) of the two models were 0.921 and 0.919, respectively. The results showed that the models constructed in this work could provide estimation stability and favorable predictive ability.     

Efficient and Eco-friendly Process for the Synthesis of Bi（indolyl）-methanes Catalyzed by Sodium Hydrogensulfate Monohydrate in Ionic Liquid n-Butylpyridinium Tetrafluoroborate

Indole fragment is featured widely in a wide variety of pharmacologically and biologically active compounds1. A large number of bi(indolyl)methanes have been reported to be isolated from terrestrial and marine natural sources, viz. parasitic bacteria, tun…