Trace Determination of Scandium Using Adsorption Voltammetry of Mix-Polynuclear Complex of Scandium-Calcium-Alizarin Red S at Carbon Paste Electrode

A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.

Molecular Design and Electronic Structure of Polynuclear Rare Earth Complexes and Clusters

Studies on the electronic structure,molecular design,syntheses of some novel series of tetranuclear rare earth complexes in our laboratory have been reviewed.Spin-unrestricted localized INDO method was used to calculate the electronic structure and the chemical bonding in the typical rare earth cluster Sc[Sc_6Cl_(12)Co]was discussed.

Polynuclear Lanthanoid Complexes Containing Aluminium—The Structure of[HoAl(CF_3COO)_2(CF_3CHOO)(C_2H_5)_2(C_4H_8O)_2]_2 at 233K

[HoAl(CF_3COO)_2(CF_3CHOO)(C_2H_5)_2(C_4H_8O)_2]_2,Mr=1468.7,monoclinic,P 2_1/n,a=1.0084(4), b=1.8453(6),c=1.4501(6)nm,β=102.40(3)°,V=2.6355(1)nm^3,Z=2,D_c=1.81gcm^(-3),F(000)=1511, T=233K,Mo Kα radiation(λ=0.071069nm).R=0.052 for 6176 unique reflections[Ⅰ≥36(Ⅰ)].The structural units consist of dimeric molecules with the mixed ligand and central bimetallic atoms,which are polynuclear lanthanoid complexes containing aluminium.Ho-Ho'distance is 0.3619(1)nm.The coordination polyhedron of Ho can be described in terms of a distored bicap-prism.

Synthesis and Structure of Polynuclear Complex [La(bphsb)_2(NO_3)_3]_n

The polynuclear complex, [La(bphsb) 2(NO 3) 3] n (bphsb=1,4 bis(phenylsulfinyl)butane) were obtained. The structure of the complex consists of ten coordinated metal ions linked up with six O atoms of the three bidentate nitrates and with four O atoms of the four bphsb ligands. The coordination polyhedron of the La 3+ may best be described as distorted bicapped square antiprism. The bphsb ligands act as bridges that join two neighbouring lanthanum ions to give polymeric chains. Each chain contains 18 membered macrocyclic rings with two La atoms. In the complex, the bphsb ligands adopt meso stereoisomer in which sulfur atoms are chiral, and the absolute configurations of the atoms are RS.

Synchronous fluorescence technique and its use in identification of polynuclear aromatic hydrocarbons in urine samples

The synchronous fluorescence spectroscopy of three polymiclear aromatic hydrocarbons was studied. It was shown that the specific Δλ of the spectra were 10nm for benzo(k) fluoranthene, 25 nm for benzo(a) pyrene, and 40 nm for pyrene. The peaks of the spectra were at 407, 404, and 373 nm for the three chemicals, respectively. Benzo(k) fluoranthene, benzo(a) pyrene, and pyrene in the urine samples from smokers were identified by high pressure liquid chromatography combined with the synchronous fluorescence spectroscopy.

Synthesis and Structural Characterization of One-dimensional Polynuclear Complex [La(bipyN_2O_2)(TFA)_3]_n

A novel polymeric complex [La(bipyN2O2)(TFA)3]n(TFA= trifluoroacetylacetone) was prepared. The X-ray structure analysis revealed that the complex has an infinite one-dimensional supramolecule structure with the 4,4'-bipyridyl-N,N'-dioxide as a bridge. La(III) is coordinated to eight oxygen atoms, six from three trifluoroacetylacetonate anions, two from two 4,4'-bipyridyl-N,N'-dioxide molecules.

Electron—rich Polynuclear Transition Metal Clusters：Ⅱ.Synthetic and S

The syntheses and structures of a novel series of polynuclear coinage metal cluster compounds are discussed. The most fascinating structural characteristic of the Au-Ag alloy clusters with Au_18Ag_19 and Au_18Ag_19 cores and phosphine ligands, which were prepared by the reduction of mononuclear coinage metal complexes R3PAuX and R3PAgX with NaBH4 in organic solution, is their construction from 13-atom gold-centred icosahedral Au_7Ag_6 building blocks. The structures of the polynuclear coinage metal clusters with R2dtc ligands are variable with either unlimited linear chain or triangular M3 units.

Proximal Input of Polynuclear Aromatic Hydrocarbons (PAHs) in Groundwater Sources of Okrika Mainland, Nigeria

The Port Harcourt Refinery Company situated at Okrika Mainland discharges its effluent into the Creeks surrounding this coastal land. The current study examined the presence of polynuclear aromatic hydrocarbons in groundwater sources of the coastal settlement. Ten replicate samples were collected from 10 boreholes in the settlement using sterilized amber glass bottles and fixed with concentrated H2SO4. They were later analyzed using Gas chromatography (GC). The Pearson product moment correlation coefficient (r) was used to determine the interactions of the PAHs detected while the One-way ANOVA was used to determine spatial variance equality in means of the PAHs components at P (971.1318) > Fcrit(3.85563)]. A further structure detection revealed that the inequalities were contributed by all the PAH components, especially between BH 3 and BH 1, BH 4 and BH 2 and 5, as well as between BH 6 and BH 10. Very strong associations were observed between the PAH components at P < 0.01. BH 8 recorded the highest contamination level of the various PAHs due basically to its proximity to the refinery’s effluent discharge point (Ekerekana Creek) and channel. Hence the source of these pollutants could best be fingerprinted to the nearby Port Harcourt Refinery Company’s effluent discharges. These PAHs are not only ingested by drinking contaminated waters, but are further consumed when this water is used to prepare foods. This creates a great cause for public health concerns especially as several PAHs are known carcinogens. It is therefore, recommended that technologically advanced techniques of water treatment be developed in order to take care of the presence of PAHs in drinking water sources of the coastal dwellers.

VIBRATIONAL SPECTRA AND STRUCTURE OF POLYNUCLEAR COPPERLANTHANOID MIXED METAL CARBOXYLATE COMPLEXES

Five complexes of copper and lanthanide series containing iminodiacetic group Hgands have been synthesized and investigated. The structures of three compounds have been determined by X-ray single crystal diffraction. Their vibrational spectra have been measured and assigned rationally.

STUDIES ON THE CHROMOPHORIC REACTIONS OF MIXED POLYNUCLEAR COMPLEXES OF RARE EARTH-ARSENAZO Ⅲ-COPPERO-PHENANTHROLINE

In an acidic solution the mixed polynuclear complexes could be formed by association of rareearth-arsenazo Ⅲ complexing anions with copper o-phenanthrolinate cations.In this paper the formationconditions of lanthanum-arsenazo Ⅲ-copper-o-phenanthroline complex and its related reaction mechanismhave been studied in detail.The complex exhibits an absorption maximum at 663 nm and its apparent molarabsorptivity is found to be 1.22×105L·mol-1·cm-1.The molar ratio of the components in the complex isestimated to be La:arsenazo Ⅲ:Cu:Phen=1:1:1:3.Its possible molecular formula can expressed as[Cu（Phen）3]（La-arsenazo Ⅲ）.The reaction is used to determine micro amounts of lanthanum（or rareearths）in copper containning synthetic samples and satisfactory results are obtained.

Electron—rich Polynuclear Transition Metal Clusters：I.The Clusters wit

This paper presents a versatile method for synthesizing electron-rich polynuclear transition metal clusters with chalcogen bridges and phosphine ligands.The reactions of transition metal complexes(R3P)2MX2(M=Co,Ni;R=Ph,Bu,Et;X=Cl,Br) with bridging reagents Na2Ex (E=S,Se;x=1.2) are described.The geometric and electronic structures of a series of polynuclear transition metal clusters with trianglar M3 units are also discussed.

Synthesis and Characterization of Condensed Polynuclear Aromatic Resin Derived from Ethylene Tar

As a kind of low-cost and readily available industrial byproduct, ethylene tar (ET) was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin (COPNAR). The basic properties of ET and the resulted COPNAR were characterized by FT-IR, 1H-NMR, TGA and elemental analysis. The test results showed that ET with high aromatic content (>50%) was suitable for the synthesis of COPNAR with superior heat resistance. The average molecular structure of ET was obtained by means of the improved Brown-Ladner method, and the reaction mechanism was considered as an acid-catalyzed positive ion-typed polymerization. Our findings have provided a new route to develop ET into technology-added heat-resistant resins.

Curing Mechanism of Condensed Polynuclear Aromatic Resin and Thermal Stability of Cured Resin

In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by proton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermogravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the curing process, and the curing mechanism was confirmed to be the electrophilic substitution reaction. Compared with the uncured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65% at 600 ℃, which was much higher than 25.02% of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.

Unprecedented 1D Mixed-metal Polynuclear Cyclometalated Platinum Complexes： Synthesis, Structural Characterization and Spectroscopic Properties

The complexes [Pt2L2（μ-dppm）]（ClO4）2 （1） and {[Pt2L2（μ-dppm）Li（CH3CN）2]（ClO4）3}n （2）, where HL is 6-[4-（diethoxyphosphorylmethyl）phenyl]-2,2′-bipyridinyl and dppm is bis（diphenylphosphino）methane, have been synthesized and characterized. In complex 1 the platinum（Ⅱ） center adopts a distorted square planar coordination geometry. The polymer 2 exhibits a ＂stairstep＂ configuration with one-dimensional Pt（Ⅱ）N^N^CPO- Li（Ⅰ）-OPC^N^ NPt（Ⅱ） mixed-metal units which are linked through dppm. Both complexes have metal-metal interaction with Pt- Pt distances of 3.325（2） and 3.1432（9） A, respectively, and display strong metal-metal-to-ligand charge-transfer （MMLCT） triplet state emission. The density-functional-theory calculation was used to interpret the absorption spectra of the complexes.

STUDY ON THE ELECTRONIC STRUCTURE OF POLYNUCLEAR YTTRIUM COMPLEX Y_5O(OR)_(13) BY DV-X_αMETHOD

The metal alkoxides are very important in the following two respects: (ⅰ) In contrary with the ordinary pi-acceptor ligands which can stabilize metal ions in low oxidation states, the alkoxide ligands can stabilize d-electron poor metals in high oxidation state. Steric control of coordination number of the central metal ion and the binding sites with

COLOUR SYSTEMS OF MIXED POLYNUCLEAR COMPLEXES OF LANTHANUM-2,7-BISAZOCHROMOTROPIC ACID DYES-ZINC-O-PHENANTHROLINE

In the preceding work we discussed the formation of mixed polynuclear complexes (MPC) of rare earth-arsenazo Ⅲ-copper-o-phenanthroline. This note reports the action rule of various 2, 7-bisazochromotropic acid dyes with different structures in this kind of colour reactions. The experiments showed that only those symmetric 2, 7-bisazochromotropic

[Co_3(1,2-S2C6H4)_3(PPh_3)_3]+, A basic triangle unit of some polynuclear molecules

[Co3(1,2-S2C6H4)3(PPh3)3][CoBr3(DMF)].sol (1, sol=CHCl3,O(C2H5)2,H2O) was obtained from the reaction of CoBr(PPh3)3 with Na2(S2C6H4) in chloroform. The Co3 core in the cation of 1 exhibits a metal-metal bonded isosceles triangle, in which the two longer Co-Co bonds are both bridged by S2C6H4 ligands on two sides of the triangle plane respectively, while the bottom short Co-Co bond is bridged by the third bidentate S2C6H4 ligand. A series of polynu-clear cobalt cluster compounds with phosphine, thiolate and/or sulphur ligands were prepared by low oxidation state Co+ with thiolates in organic solvents. These tri-, tetra-, hexa-, heptanuclear cluster compounds 1-8 with various types of crystal structures can be viewed as the condensed polynuclear cobalt complexes that the cobalt atom frameworks with sulphur bridged were built through the small triangular units of [Co3S3nL3] (n=1,2) with or without [CoL] (L=PR3, Br, Cl, 5-C5H5) fragments.

Novel Roles of Metal Ions in Layered Self-assembled Films of Polynuclear Complexes on Their Photoinduced Electron Transfer Properties

Three metal ion bridged self-assembled （SA） films of cis-di（thiocyanato）-bis（2,2＇-bipyridyl-4,4＇-dicarboxylate） ruthenium were fabricated and characterized by contact angle, UV spectra, cyclic voltammetry and XPS. Their photoinduced electron transfer properties （PETP） were examined. Among the titled systems, the highest steady anodic photocurrent of 1773-1843 nA/cm^2 and the highest quantum yield of 3.2% were achieved. The effects of incident light intensity, bias voltage, and electron donor were also studied. The possible mechanism of electron transfer was proposed. The results reveal that different metal ion in SA films could affect significantly the photoinduced electron transfer property. Our experimental results clearly show that bridging metal ions can play both functional and structural roles in these self-assembled systems. This method of forming functional films can provide a new approach to regulate the property of similar systems.

Substituent-Mediated Transformation of Polynuclear Gold(I)-Sulfido Complexes—From Pentanuclear to Octadecanuclear Cluster-to-Cluster Transformation

Polynuclear gold complexes show diverse structures and bonding.An exploration into their transformation represents a challenging area of research.Herein,an unprecedented substituent-mediated transformation from pentagold(I)to octadecagold(I)complexes has been observed.These gold(I)-sulfido complexes with distinct structures have been fully characterized,and the transformation process has been monitored by NMR spectroscopy in solution state.

广州周边菜地中多环芳烃的污染现状

以GC/MSD内标法分析了广州五个地区菜地中 1 6种多环芳烃 (PAHs)的分布 ,结果表明 ,菜地土壤中∑PAHs最大为 30 77μg·kg- 1 ,最小为 42 μg·kg- 1 ,绝大部分土壤样品中的∑PAHs含量在 2 0 0 μg·kg- 1 以上 ,属中度污染 .