Distribution of Cd and Pb in a wetland ecosystem

Cadmium and lead contents in sediments, dominant species of plants (Phargmites aus-tralis and Scripus mariquter), benthos (Helice tridens tientsinensis, llyoplax deschampsi, and Bul-lacta exarata), and waders (Calidris ruficollis) on the Eastern End of Chongming Island were measured. The results showed that, for cadmium, there are clear stratification in the sediment of reclaimed area and bio-amplification in food chain. However, for lead, a phenomenon was different. The amplification factors (AFs) for cadmium of primary producers, primary consumers, and secondary consumers were 2.59-12.38, 0.09-8.44, and 51.1, respectively. For lead, AFs of primary producers, primary consumers and the top trophic layer were 0.29-2.62, 0.06-5.62, and 7.31, respectively. Each species of macrobenthos showed different strategies to cadmium and lead. Large-sized crabs accumulated more lead, while small-sized crabs and snails accumulated more cadmium. Waders had significantly highest AFs for cadmium and lead in the study. Tha     

Reusable resistive aptasensor for Pb(II) based on the Pb(II)-induced despiralization of a DNA duplex and formation of a G-quadruplex

The article describes a reusable biosensor for Pb(II) ions. A duplex DNA with a terminal amino group and containing a G-quadruplex (G4) aptamer was covalently conjugated to single walled carbon nanotubes on a field effect transistor (FET). The detection scheme is based on the despiralization of the DNA duplex because Pb(II) can induce the G4 aptamer to form a stabilizing G4/Pb(II) complex. This structural change affects the electrical conductivity of SWNTs which serves as the analytical signal. The biosensor was characterized via scanning electron microscopy, Raman, UV-vis, and voltage-current profiles. Under optimized conditions, the relative resistance at 0.02 V increases linearly with the logarithm of the Pb(II) concentration in the range from 1 ng·L^?1 to 100 μg·L^?1, and the limit of detection is 0.39 ng·L^?1. Compared to other sensors, this oner demonstrates superior simplicity, sensitivity, and selectivity even in mixtures of heavy metal ions. It was applied to the determination of Pb(II) in (spiked) water and soil samples and gave good results.

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Graphical abstract Schematic of the fabrication a biosensor for Pb(II). It is making use of an SWNT-based FET, G4-DNA and complementary DNA with an amino group. Pb(II) can despiralize the DNA duplex to form a G-quadruplex which affects the electrical conductivity of SWNTs. After each detection, the single complementary strand DNA can rebind the G4-DNA, which makes the biosensor reusable.

     

Synthesis,Structure and Photoluminescence of a New Pb(Ⅱ) Coordination Polymer [Pb(1, 4-chdc)(L)]_n·nH_2O Based on a Flexible 1,4-Cyclohexanedicarboxylic Acid

A new Pb(Ⅱ) coordination polymer, [Pb(1,4-chdc)(L)]_n·nH_2O(1), was synthesized under hydrothermal condition(1,4-H2 chdc = 1,4-cyclohexanedicarboxylic acid and L = 2-(3-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline). Its crystal structure was determined by singlecrystal X-ray diffraction. Compound 1 crystallizes in triclinic, space group P1 with a = 9.1182(8), b = 11.3249(10), c = 12.7326(12) ?, α = 77.897(2), β = 81.644(2), γ = 84.491(2)°, V = 1269.0(2) ?~3, Z = 2, C_(27)H_(24)FN_4O_5Pb, M_r = 710.69, D_c = 1.860 g/cm~3, F(000) = 690, μ(MoKa) = 6.701 mm~(-1), R = 0.0349 and wR = 0.0746. In 1, each 1,4-chdc anion bridges two neighboring Pb(Ⅱ) atoms in a bidentate chelating coordination mode to give a chain structure. The L ligands are attached on one side of the chain through chelating the Pb(Ⅱ) atoms, and are stacked with those of an adjacent chain through π-π interactions, yielding a layer structure. The O–H···O and N–H···O hydrogen bonding interactions further stabilize the supramolecular layer structure of 1. Moreover, solid state luminescent property of 1 was also studied.     

Synthesis,Characterization and Thermostability of a Novel Pb(Ⅱ) Coordination Polymer with Mixed Ligands

A novel mixed-ligand coordination polymer [Pb(phen)(NNDS)(H2O)]n·n H2O(1) was obtained from the reaction of 1,10-phenanthroine(phen), Pb(OAc)2 and sodium 1-nitroso-2-naphthol-3,6-disulfonate(Na2NNDS) in a mixed solvent. The complex was characterized by elemental analysis, IR and X-ray single-crystal diffraction. Crystal data for 1: monoclinic, space group P21/c, a = 11.5835(9), b = 14.6334(11), c = 13.9030(11) ?, β = 98.4180(10)o, V = 2331.3(3) ?3, Z = 4, Mr = 754.70, Dc = 2.150 mg/m3, μ = 7.483 mm-1, F(000) = 1456, the final R = 0.0430 and w R = 0.0841 for 4221 observed reflections with I 2σ(I). The Pb(II) center is coordinated by six O and two N atoms showing a distorted dodecahedron configuration. The multidentate ligand of NNDS dianion exhibits peculiar coordination mode, and the two O atoms of two sulfonate anions bridge two Pb(II) cations into a dimer, and the O atom of nitroso group links the other dimer into 2D sheets extending in the [011] plane. There exist significant π-π stacking interactions between adjacent phen and NNDS. The 3D network is formed by 2D sheets interlinked by hydrogen bonds and π-π stacking interactions. The thermostability of 1 was investigated by TG and DSC.     

Surface tension of liquid high-entropy equiatomic alloys of a Cu–Sn–Bi–In–Pb system

An experimental study of the temperature dependences of the surface tension of liquid high-entropy equiatomic alloys of a Cu–Sn–Bi–In–Pb system is conducted. Measurements are made within the temperature range of t _L to 1300°C in the mode of heating and subsequent cooling of a sample. Overcooling of a melt prior to crystallization is detected. The depth of overcooling grows along with the number of components in the melt, while the temperature coefficient of surface tension falls. The experimental results qualitatively interpreted within the concepts of the specific surface entropy of a liquid.     

Pb2+-TTA-偶氮磺Ⅲ高灵敏反应用于测定食品添加剂中的Pb

研究了3,6-双(4-溴-2-磺基-苯偶氮)-4,5-二羟基-2,7-萘二磺酸(溴代磺酸偶氮Ⅲ)、噻吩甲酰三氟丙酮(TTA)与Pb(Ⅱ)的显色反应。结果表明,Pb(Ⅱ)与溴代磺酸偶氮Ⅲ、TTA形成1∶1∶1的蓝绿色络合物,其最大吸收波长为659.8nm,络合物的表观摩尔吸光系数ε=6.42×105L.min-1.cm-1,Pb量在0~2.49μg/mL范围内符合比耳定律,检出限为5.27×10-3μg/mL,相对标准偏差(RSD)为0.4%~4.4%(n=5)。该方法灵敏度高,操作简便,用于市售色素和香精样品中铅的测定,加标回收率为84.96%~100.5%。     

Ba—Pb—O和Bi—Pb—O的电化学合成和表征

本文研究了用电化学方法在水溶液中合成铅基氧化物Ｂａ－Ｐｂ－Ｏ和Ｂｉ－Ｐｂ－Ｏ的方法，并采用ＸＰＳ，ＸＲＤ和ＥＤＸ对电合成产物进行了表征。     

Hydride generation – in-atomizer collection of Pb in a quartz trap-and-atomizer device for atomic absorption spectrometry – an interference study

Interferences of selected hydride forming elements (As, Sb, Bi, Se and Sn) on lead determination by hydride generation atomic absorption spectrometry were extensively studied in both on-line atomization and preconcentration (collection) modes. The commonly used on-line atomization mode was found free of significant interferences, whereas strong interference from Bi was observed when employing the preconcentration mode with plumbane collection in a quartz trap-and-atomizer device. Interference of Bi seems to take place in the preconcentration step. Interference of Bi in the collection mode cannot be reduced by increased hydrogen radical amount in the trap and/or the atomizer.     

关于Bi系高Tc超导体的阳离子掺杂研究（Ⅰ）：Al—Pb,Mg—Pb和Mn—Pb二…

讨论了Ａｌ－Ｐｂ，Ｍｇ－Ｐｂ和Ｍｎ－Ｐｂ等二元阳离子掺杂对Ｂｉ系高Ｔｃ超导相出现时间的影响。试验中发现，前人较少讨论的Ｍｇ＾３＋或Ａｌ＾３＋离子在高Ｔｃ相形成时，进入到高Ｔｃ超导体晶棰的特定位置，它们在高Ｔｃ超导相中起着各自不同的作用机制，从而影响了高Ｔｃ超导相的结构和超导电性。     

Development of a green effervescence-assisted dispersive liquid–liquid microextraction method using a home-made tablet disperser for trace analysis of Cd(II) and Pb(II)

An analytical approach for the determination of trace amounts of Cd(II) and Pb(II) has been developed using a home-made tablet-based effervescence-assisted dispersive liquid–liquid microextraction (DLLME) method which was performed in a narrow-bore tube, followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate and NaCl was used to make the disperser tablet. Then, microlitre level of an extraction solvent was added in the tablet, and then, it was released into a narrow-bore tube containing sample solution and a complexing agent. An acid–base reaction immediately occurred between tartaric acid and sodium bicarbonate, and the produced CO₂ led to the dispersion of the extraction solvent into the solution as tiny droplets and subsequent extraction of the analytes. The method made possible the determination of Cd(II) and Pb(II) in the ranges of 0.1–10 and 1.0–20 µg L^?1, respectively. The limits of detection were obtained 0.43 and 0.05 µg L^?1 for Pb(II) and Cd(II), respectively. The limits of quantifications were 0.80 and 0.09 µg L^?1 for Pb(II) and Cd(II), respectively. Repeatability of the method, which is expressed as relative standard deviation, was obtained 3.1% (n = 6, C = 2 µg L^?1) and 1.3% (n = 6, C = 0.2 µg L^?1) for Pb(II) and Cd(II), respectively. The accuracy of the developed method was verified by analysing a certified reference material, namely SPS-WW2 Batch 108. Relative recoveries (84–107%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples and fruit juices. The method was shown to be fast, reliable and environmentally friendly with low organic solvent consumption.     

Intermetallische Phasen mit β-Wolfram-Struktur (V3Pb,Nb3Pb und V3Cd)

Zusammenfassung Neue Phasen mit -Wolfram-Struktur (Cr₃O-Typ) werden in den Systemen V–Pb, Nb–Pb und V–Cd hergestellt und deren Gitterparameter bestimmt.     

Synthesis and Crystal Structure of a 1-D Coordination Polymer [Pb（ANS）2（phen）]n

A new one-dimensional coordination polymer, [Pb(phen)(ANS)2]n (ANS = 2-ami- nonaphthalene-1-sulfonate, phen = 1,10-phenanthroline), has been prepared by hydrothermal synthesis and structurally characterized by elemental analysis, IR and single-crystal X-ray diffrac- tion. The results determined by XRD reveal that the complex crystallizes in monoclinic, space group P21/c with a = 16.8374(14), b = 16.9825(14), c = 9.9392 (8) , β = 95.9830(10)o, V = 2826.5(4) 3, Mr = 831.86, Dc = 1.955 g/cm3, μ(MoKα) = 6.173 mm-1, F(000) = 1624, Z = 4, the final R = 0.0272 and wR = 0.0694 for 4305 observed reflections (I > 2σ(I)). In the complex, the adjacent lead(II) ions are bridged through the oxygen atoms of sulfonate groups in a syn-syn conformation, yielding an infinite zigzag chain. And the intermolecular N–H···O hydrogen bonds link the chains into two-dimensional layered networks, which are further assembled into a separate two-layer-film-like packing structure.     

Synthesis and Crystal Structure of a New Lead Coordination Polymer： [Pb（L）（1,4-ndc）]

The title coordination polymer, [Pb(L)(1,4-ndc)] 1 (L = 2-(4-fluorophenyl)-1Himidazo[4,5f1,10]phenanthroline, 1,4-ndc = naphthalene-1,4-dicarboxylic acid), has been obtained by using hydrothermal synthesis and characterized by elemental analysis, IR and singlecrystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 10.1043(11), b = 14.3162(15), c = 17.6061(18), β = 95.3990(10)°, V = 2535.5(5)3, Z = 4, C31H17FN4O4Pb, Mr = 735.68, Dc = 1.927 g/cm3, F(000) = 1416, μ(MoKa) = 6.709 mm-1, R = 0.0201 and wR = 0.0489. The 1,4-ndc dianions link neighboring Pb(II) atoms in a bis-chelating mode, yielding a one-dimensional chain structure along the c axis. The C–H···π interactions between the carbon atom of L ligand and the benzene ring of 1,4-ndc lead the one-dimensional chains to form a two-dimensional supramolecular layer. The π-π interactions between L ligand and 1,4-ndc ligand make the two-dimensional layers generate a three-dimensional supramolecular architecture. Additionally, the N–H···O hydrogen bonds further stabilize the structure of 1.     

Volatile Pd–Pb and Cu–Pb heterometallic complexes: structure,properties, and trans-to-cis isomerization under cocrystallization of Pd and Cu β-diketonates with Pb hexafluoroacetylacetonate

Preparation of volatile heterometallic precursors is a significant step on the way to advanced multicomponent materials. Study of molecular transformations in solution upon precursor synthesis is of importance to optimize the preparation of the stable solid product of desired composition. Two new volatile heterobimetallic complexes, cis-PdL₂*Pb(hfa)₂ and cis-CuL₂*Pb(hfa)₂, were obtained (L = 2-methoxy-2,6,6-trimethylheptane-3,5-dionate, hfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) under cocrystallization of trans-bis-beta-diketonates of Pd(II) and Cu(II) with Pb(hfa)₂ from organic solvents. Crystals of these compounds are built of discrete bimetallic molecules where transition metal complex isomerized from trans-to-cis form. Complexation followed by isomerization was studied by solution NMR. The bimetallic molecular species were formed early in solution. Enthalpy and activation energy of isomerization were estimated to be 49 and 93 kJ mol^?1, respectively. A new synthesis technique of Pd(II) beta-diketonates which is distinguished by simplicity and selectivity as well as the crystal structure of trans-PdL₂ is described. Volatility of all obtained compounds was confirmed by thermogravimetric analysis and fractional sublimation in vacuum; Pd-containing heterobimetallic complex appeared to be more volatile than both the initial monometallic complexes and Cu-containing complex.     

含Pb铝合金表面的电化学溶解趋势

利用一个简单层状模型通过第一性原理的密度泛函理论研究了表面Pb含量变化对Al(100)表面Al原子的化学势和电化学溶解电势的影响规律.计算结果表明,当表面层Pb含量为1/9、1/4、1/2和3/4 ML(monolayer)时,与纯铝相比,表面Al原子的化学势分别升高了0.13、0.17、0.57和0.64 eV,表面Al原子的溶解电极电势分别偏移了-0.04、-0.06、-0.19和-0.21 V.溶解电势向负方向偏移,表明含Pb的Al(100)表面的Al原子在更低的电势条件下就可以溶解了.同时,表面Pb含量不同会引起表面Al原子向内不同程度的弛豫,导致表面Al的化学环境和表面结构发生变化,进一步表明金属表面原子的化学势和溶解电极电势受原子周围的化学环境的影响.表面Mülliken电荷布居分析证实,随着表面Pb含量增加,Pb原子与Al原子之间的电荷交换作用增强,使表面Al原子总的负电荷数增加,导致表面电位下降,表面功函数也减小,也促使Al表面更易于发生电化学腐蚀反应.     

Synthesis and Crystal Structure of a Novel Tetranuclear Complex [Pb4（HQ）6（NO3）2]

Reaction of 8-hydroxyquinoline （HQ） with Pb（NO3）2 in water resulted in the formation of a tetranuclear complex [Pb4（HQ）6（NO3）2] 1. It has been characterized by IR, elemental analyses and X-ray diffraction. Crystal data for this complex： triclinic system, space group P1, a = 9.7399（6）, b = 11.6535（8）, c = 12.6806（8） A, α = 62.8050（10）, β = 78.4910（10）, γ = 80.5490（10）°, C54H36N8O12Pb4, Mr= 1817.67, Z = 1, V = 1250.04（14）A^3, Dc = 2.415 g/cm^3,μ = 13.503 mm^-1, -12≤h≤8, -14≤k≤13, -15≤1≤15, F（000） = 840, Rint = 0.0217, R= 0.0348 and wR = 0.0927. X-ray crystal structure analysis revealed that in 1 each Pb（ II ） contains a stereo- chemically active lone pair of electrons. The Pb…C interaction, C-H……O weak interaction and π…π stacking interactions are observed in the complex. In the solid state, the complex possesses strong photoluminescent emission at 485 and 528 nm.     

Selective visual detection of Pb(II) ion via gold nanoparticles coated with a dithiocarbamate-modified 4′-aminobenzo-18-crown-6

We have developed a crown ether based selective colorimetric sensing scheme for the determination of Pb(II) ion by using gold nanoparticles modified with dithiocarbamate derivative of 4′-aminobenzo-18-crown-6 that acts as a colorimetric probe. Monodisperse Au-NPs were prepared by reacting 4′-aminobenzo-18-crown-6 with carbon disulfide to generate the dithiocarbamate ligand which was then added to the Au-NPs to form a supramolecular assembly on their surface. The Au-NPs modified in this way undergo aggregation in the presence of Pb(II) ions, and this causes the color to change from red to blue. The Pb(II)-induced aggregation can be monitored by using UV-visible spectrometry and even with the bare eye. The absorbance ratio (A_650nm/A_520nm) is linearly related to the concentration of Pb(II) in the 0.1 to 75 μM range (with a correlation coefficient of 0.9957), and the detection limit is 50 nM which is lower than the allowable level (75 nM) as defined by the US EPA. The method was successfully applied to the determination of Pb(II) in spiked water samples.

Schematic representation of Pb²⁺ ion-induced DTC-CE-Au NPs aggregation via sandwich complex formation.

     

XRF法快速测定粉饼化妆品中Pb

讨论了粉饼类化妆品的成分配比,通过添加分析纯Pb粉末,采用硼酸镶边垫底的粉末压样法,制备了用于X射线荧光分析的粉饼类化妆品Pb元素的标准样品,保证了标样和待测样品基体大致相同。在XRF分析过程中选择Pb Lβ作为分析线,建立了粉饼类化妆品Pb元素的工作曲线,其线性相关系数为0.9977,检出限为2.30μg/g。对市售5款粉饼化妆品进行了Pb含量检测,样品加标回收率为106%;待测样品RSD为2.7%(n=11);5款样品中有2款Pb含量略高于当前国标限值。     

Selective visual detection of Pb(II) ion via gold nanoparticles coated with a dithiocarbamate-modified 4′-aminobenzo-18-crown-6

We have developed a crown ether based selective colorimetric sensing scheme for the determination of Pb(II) ion by using gold nanoparticles modified with dithiocarbamate derivative of 4′-aminobenzo-18-crown-6 that acts as a colorimetric probe. Monodisperse Au-NPs were prepared by reacting 4′-aminobenzo-18-crown-6 with carbon disulfide to generate the dithiocarbamate ligand which was then added to the Au-NPs to form a supramolecular assembly on their surface. The Au-NPs modified in this way undergo aggregation in the presence of Pb(II) ions, and this causes the color to change from red to blue. The Pb(II)-induced aggregation can be monitored by using UV-visible spectrometry and even with the bare eye. The absorbance ratio (A_650nm/A_520nm) is linearly related to the concentration of Pb(II) in the 0.1 to 75 μM range (with a correlation coefficient of 0.9957), and the detection limit is 50 nM which is lower than the allowable level (75 nM) as defined by the US EPA. The method was successfully applied to the determination of Pb(II) in spiked water samples. Figure

Schematic representation of Pb²⁺ ion-induced DTC-CE-Au NPs aggregation via sandwich complex formation.