噻二嗪衍生物的合成及Pb2+在水/1,2-二氯乙烷界面转移的电化学性质

The transfer of Pb2+ facilitated by interfacial complexation with 5-(4-phenoxyphenyl)-6H-1,3,4-thiadiazin-2-amine(PPTA) at the polarized water/1,2-dicholoroethane(1,2-DCE) interface was investigated by cyclic voltammetry.We synthesized the thiadiazine derivative,PPTA,firstly.The transfer was performed at different metal concentrations and scan rates,and the obtained voltammetric transfer peaks toward Pb2+ ion over other divalent cations(Zn2+,Co2+,Ni2+,Cd2+,Hg2+,and Cu2+) were reversible.The dependence of the half-wave potentials of the Pb2+ ion on the concentration of PPTA in the organic phase indicates that the ion transfer is facilitated by the formation of 1:2(metal:ligand) complex in the organic phase with the association constant(lgβ2) of(17.1±0.2).     

DFT Study on the Germanium Ion Activated C–H Bond in Methane

Thermal reactions of methane with the main group metal cations Ge~+,GeO~+,GeOH~+ and OGeOH~+ were investigated by state-of-the-art quantum chemical calculations.For GeO~+/CH_4,a H atom in CH_4 abstracted by the O atom in GeO~+ to form GeOH~+ and CH_3˙constitutes the channel mainly.The barrier-free process,combined with a large exothermicity,suggested a fast and efficient reaction in agreement with the experiment.For OGeOH~+ and CH_4,the intermediates and products of the most favorable path were below the reactant asymptote,and the reaction was easy to take place,while for Ge~+ and GeOH~+,the activation of C–H bond in methane was hard to happen under ambient temperature.The results showed,in contrast to the inertness of Ge~+ and Ge OH~+,the GeO~+ and OGeOH~+ can activate the H_3C–H bond.The NBO natural charge and molecular electrostatic potential were used to analyze the four main group metal germanium constructions.The phenomenon suggested that ligands affect the electronic character and tune the chemical features of metal germanium center.     

Al_2O_3负载Cu,Fe或Ni掺杂氧化钼催化乙苯氧化脱氢(英文)

Molybdenum-based catalysts supported on Al_2O_3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was supported using an unconventional route that combined the polymeric precursor method(Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction(XRD), N_2 adsorption-desorption isotherms, temperature-programmed reduction of H_2(H_2-TPR),and thermogravimetric(TG) analysis. XRD results showed that the added metals were well dispersed on the alumina support. The addition of the metal oxide(Ni, Cu, or Fe) of 2 wt% by wet impregnation did not affect the texture of the support. TPR results indicated a synergistic effect between the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conversion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.     

Adsorption of Pb~(2+) and Cu~(2+) with Unburned Desulphurization Slag Modified Nickel Slag

Desulphurization slag modified nickel slag adsorbent was prepared by unburned forming technology. The structure of the sample was characterized by BET,XRD,IR,SEM and EDAX. The adsorption performance of Pb~(2+) and Cu~(2+) onto the resultant adsorbent from aqueous solution was studied. Results indicated that the adsorbent possesses a network pore structure formed by the AFt and C–S–H through cross lapping; the adsorbent contains a large number of Si–OH and Al–OH functional groups. The presence of functional groups not only provides abundant adsorption sites for Pb~(2+) and Cu~(2+),but also improves the adsorption performance of Pb~(2+) and Cu~(2+) from waste water through the complexation of heavy metal ions. The result of specific surface area analysis showed that the adsorbent sample possesses mesoporous structure and the BET specific surface area is 27.15 m~2/g. The solution p H values for the adsorption of Pb~(2+) and Cu~(2+) were optimized to be 6 and 5.5,respectively. The adsorption capacities of Pb~(2+) and Cu~(2+) gradually increase,whereas the removal rates of the two metal ions decrease with increasing the initial concentration of simulated solution. The resultant adsorbent gives a higher adsorption capacity for Cu~(2+) than for Pb~(2+) in the single ion solution. However,it shows preferential adsorption of Pb~(2+) rather than that of Cu~(2+). Meanwhile,results of recyclability indicate the remarkable regeneration capacity,re-adsorption ability and reusability performance of the adsorbent sample.     

THE STIMULATORY EFFECT OF HEAVY METAL CATIONS ON PROLIFERATION OF AORTIC SMOOTH MUSCLE CELLS

Heavy metal cations Cd~(2+), Pb~(2+), and Hg~(2+)were added to substitute for Ca~(2+)in culture media to study their effect on the relationship between CaM and the proliferation of cultured rabbit aortic smooth muscle cells (ASMC). It was found that all the heavy metal cations studied stimulated the proliferation of ASMC in varying degrees, increased the CaM content in cells at late G_1 stage and decreased the activity of cAMP PDE. These results suggest that the adverse effect of heavy metals may be related to the pathogenesis of atherosclerosis and hypertensive disease.     

MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER-STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (e.e.) value (71.4%) obtained without the presence of metal cations, obvious e.e. enhancement (up to 82.5%) was resulted from the addition of Zn^2 but with a certain decrease in activity. The reaction parameters in the presence of Zn^2 were also studied. It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.     

浸渍硅胶薄层色谱板分离钴和镍及数字图像分析法定量(英文)

Thin layer chromatography(TLC) of cobalt and nickel has been performed on silica gel layers induced with alkali mediated cellulose extract.A novel combination of 10% aqueous solutions of Tween-20 and potassium thiocyanate in 1∶1(v/v) was identified as the best mobile phase for the selective separation of Co2+from Ni2+on the impregnated Silica Gel G layers.The chromatographic characteristics of the cations were studied and the limits of detection as well as the limits of quantification for Co2+and Ni2+were determined.The quantitative estimation of the cations was achieved from the digital image analysis of respective chromatograms.The proposed quantitative method was successfully applied with 0-0.50% error for the determination of Co2+from Ni2+in spiked samples of bauxite,soil and rock containing common cations such as Al3+,Fe2+,Ti4+,Zn2+,Mn2+,Cu2+,Cr6+,Mg2+,etc.under the optimized chromatographic conditions.     

Effect of cation(Li~+, Na~+, K~+, Rb~+, Cs~+) in aqueous electrolyte on the electrochemical redox of Prussian blue analogue(PBA) cathodes

Prussian blue analogue(PBA) material is a promising cathode for applications in Na-ion and K-ion batteries which can support high c-rates for charge and discharge. In this study, the material of composition[K_2 Cu~IIFe~II(CN)6] was synthesized and its structural and electrochemical redox behavior was investigated with 5 different alkali insertion cations(Li~+, Na~+, K~+, Rb~+, Cs~+). Galvanostatic measurements indicate that the redox potential strongly depends on the ionic radius of the inserted cation. The redox potential varies by ~400 m V between using Li~+(0.79 ?A) or Cs~+(1.73 ?A) in the electrolyte. The underlying modification of the Fe~(2+)/Fe~(3+)redox potential in PBA is proposed to be due to the weakening of the Fe–C bond in the material. This hypothesis is supported by XRD measurements which reveal that the lattice parameter of the de-intercalated host structure follows the same trend of monotonic increase with the cation size. The relatively minor volume changes accompanying the redox(1.2%–2.4%) allow the PBA to accommodate differently sized cations, although the structural hindrances are quite pronounced at high c-rates for the larger ones(Rb~+and Cs~+). Cycle aging studies indicate that the minimum capacity fade rate is observed in case of K~+ and Rb~+ containing electrolyte. The peak intensity corresponding to the[220] crystallographic plane varies depending on the state of charge of PBA, since this plane contains the insertion cations. Owing to the sensitivity of the redox potential to the insertion cation coupled with the observed fast ion-exchange ability, the PBA material may find additional analytical applications such as ion sensing or filtration devices.     

Surface modification of MCM-41 and its application in DNA adsorption

Three types of MCM-41 absorbents, namely, Al~(3+)–MCM-41, La~(3+)–MCM-41, and Zn~(2+)–MCM-41, were prepared through amine grafting, phosphonate modification, and metal ion chelation and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and N2adsorption–desorption analysis. Results revealed that functionalized MCM-41 maintains the original structure of the molecular sieve and that the pore diameter and surface area are reduced compared with those of pure MCM-41. The adsorption behavior of DNA molecules on the surface of the modified molecular sieves was discussed according to the hard-soft acid–base(HSAB) principle. Experimental results showed that DNA purification could be effectively carried out on functionalized MCM-41 and that DNA is easily released by3–4 molL~(-1)NaCl solution. This study could be used as a general platform for future work on DNA adsorption and enrichment.     

Double layered, one-pot hydrothermal synthesis of M-TiO2 (M = Fe3+, Ni2+, Cu2+ and Co2+) and their application in photocatalysis

A double layered,one-pot hydrothermal method was adopted in this work to prepare transition metal ions(Fe3+,Ni2+,Cu2+and Co2+)doped TiO2.The morphology and chemical properties of TiO2and the status of metal ions were characterized with XRD,TEM,BET,UV-Vis and XPS analysis.TEM images show that the obtained TiO2was very uniform with an average particle size of 10.4 nm.XPS,TEM and XRD results show that transitional metals were doped onto TiO2in the form of ions.Photocatalytic decomposition of oxalic acid under UV illumination and methylene blue degradation under visible light on these materials were conducted,respectively.The results reveal that Cu2+-TiO2and Co2+-TiO2showed a highest activity under UV and visible light illumination,respectively,and they were both more active than commercial P25 TiO2.With this special design of double layers,the hydrolysis of titanium precursor in the system with water can be easily controlled and metal ions are simply doped.This strategy can be further applied to synthesize metal ion doped TiO2using various metal precursors with controllable amounts,and thus lead to better optimization of highly active photocatalyst.     

Synthesis and metal extraction behavior of pyridine and 1,2,4-triazole substituted calix[4]arenes

Three series of heterocycle substituted calixarenes, derivatized at lower and upper rim, were synthesized and successfully evaluated for metal extraction towards alkali, alkaline, transition and heavy metal ions. The presence and placement of sulfur, heterocycle functionality at upper/lower rim played a crucial role toward the extractability and selectivity of metal ions. The lower rim substituted calixarenes have shown high extractability and poor selectivity. In contrast to this, upper rim substituted calixarenes exhibited good selectivity. Moreover, sulfur functionalized calixarenes have shown better selectivity for heavy metal ions than alkali and alkaline metal ions. Among upper rim substituted calixarenes, 17 and 18 were found to be suitable for Na⁺, K⁺ and Ag⁺, 19,13 for heavy metal ions i.e., Pb²⁺, Hg⁺, Hg²⁺ and Ag⁺, and 11,12 for Pb²⁺ and Ag⁺ only.     

The Synthesis and Characterization of a Novel vic-Dioxime and its Mononuclear Complexes Bearing an 18-Membered 2 O 2 S 2 Macro-Cycle and Their Characteristics as Extractants for Transition Metal Ions

A new (E, E)-dioxime (H ₂ L) containing a diazadioxadithia macrocyclic moieties has been synthesized by reaction of an aromatic primary amine with cyanogendi-N-dioxide. The BF₂ ⁺-capped Ni²⁺ mononuclear complex of this new oxime has been synthesized using a precursor hydrogen-bridged mononuclear Ni²⁺ complex. The solvent extraction of transition metal cations by (3) and (6) with picrate anion into chloroform has been studied at 25 °C and UV-visible spectroscopy. The extractability and selectivity of transition metal picrates, (Pb²⁺, Ni²⁺, Co²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ag⁺) has been evaluated. The structures of new compounds are identified by using elemental analysis, ¹H and ¹³C-NMR, IR and MS spectral data.     

A convenient synthesis of new thiaazacrown ethers and study of their complexation reactions with some transition metal cations in binary acetonitrile–chloroform mixture using the conductometric method

Three novel thiaazacrown ethers 1, 2 and 3 were synthesized in a simple way and in high yield. The complex formation between Ag⁺, Cu²⁺, Zn²⁺, Pb²⁺, Hg²⁺ and Cd²⁺ metal cations with thiaazacrown ethers 1, 2 and 3 have been studied in acetonitrile:chloroform (1:1) binary solvent system using conductometric technique. The conductance data show that the stochiometry of the complexes with Ag⁺, Cu²⁺ and Zn²⁺ cations is 1:1 (L:M), but in the case of Pb²⁺ and Hg²⁺ cations, a 1:2 (L:M) complex is formed in solutions. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data at 25 °C. It was found that the stability constants of 1-Ag²⁺, 2-Ag⁺ and 3-Ag⁺ complexes are higher than those of their corresponding Zn²⁺ and Cu²⁺ complexes and found to vary in order 3 > 1 > 2 for Ag⁺.     

Aminopyridyl derivative of thiacalix[4]arene-carboxylic acid as ionizable highly selective Ag+ ionophore

A novel mono-ionizable receptor 2 possessing three aminopyridyl and one carboxylic group in 1,3-alternate conformation based on thiacalix[4]arene, confirmed by single crystal X-ray analysis, was prepared. For competitive solvent extraction of alkali metal (Na⁺, K⁺ and Cs⁺) and some transition metal (Cu²⁺, Zn²⁺, TI⁺, Ag⁺) cations from aqueous solutions into chloroform, it was found that the introduction of proton-ionizable group (carboxylic acid moiety) into the aminopyridyl-thiacalix[4]arene derivative could further improve its Ag⁺ extractability with high selectivity.     

Syntheses and structure of 2,11-dithia[3.3](2,6)pyrazinophane and its coordination complexes of Cu(I) and Co(II)

The cyclophane ligand, 2,11-dithia[3.3](2,6)pyrazinophane (L), was synthesized by a simpler method and characterized by ¹H NMR, which was used to synthesize coordination complexes by reactions with Cu⁺ (I) and Co²⁺ (II) cations. Single-crystal X-ray analysis revealed that the conformation of the ligand L is syn(boat-chair), while in I and II it adopts syn(boat-chair) and syn(chair-chair), respectively. In the former coordination compound, Cu(I) is coordinated with two nitrogen and one sulfur atom of the ligand. In the latter one, Co(II) is coordinated with two nitrogen and two sulfur atoms of the ligand. In complexes I and II, the formation of three-dimensional structure depends on π-π-stacking and hydrogen bonds.     

Syntheses, spectroscopic characterization and metal ion binding properties of benzo-15-crown-5 derivatives and their sodium and nickel(II) complexes

New benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared. Nitro compound (1) was prepared after the reaction?4′,5′-bis(bromethyl)benzo-15-crown-5 and o-nitrophenol in the presence of NaOH. After reduction process by using hydrazine hydrate and Pd/C amine compound (2) was formed. New crown ether imine compounds (3–5) were synthesized by the condensation of corresponding crown ether diamine (2) with salicylaldehyde derivatives. Sodium complexes of the crown compounds (1a–5a) form crystalline 1:1 (Na⁺: ligand) complexes with sodium perchlorate. Nickel(II) complexes (3b–5b) with 1:1 (Ni²⁺:ligand) stoichiometries were also been synthesized from the Schiff bases (3–5). The results indicated that the Schiff base ligands coordinated through the azomethine nitrogen and phenolic oxygen. The extraction ability of compounds (1, 3, 4 and 5) were also evaluated in chloroform by using several alkali and transition metal picrates such as Li⁺, Na⁺, K⁺, Cr³⁺, Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Pb²⁺.     

Synthesis and cation complexation of calix[4]azacrowns and a spirobiscalix[4]azacrown

The synthesis and complexation properties of three new derivatives, one spirobiscalix[4]azacrown (1) and two calix[4]azacrown (2 and 3), are reported. Complexation studies of the three ligands toward transition and heavy metal cations have been carried out and monitored by UV absorption spectrophotometry in acetonitrile. Mononuclear complexes were detected for all complexes, whereas binuclear species (M₂L) were also formed in the case of ligand 1 with Cu²⁺ and Pb²⁺. The extraction properties of 1, 2 and 3 toward Cu²⁺, Zn²⁺, Pb²⁺, Ag²⁺ and Cd²⁺ are also reported. The results showed that complexation is the main factor affecting extraction with ligands 2 and 3, while with ligand 1 it is not.     

Synthesis of crownophanes possessing three pyridine rings

Novel crownophanes with three pyridine moieties (pyridinocrownophanes 4 and 5) were prepared by means of intramolecular [2+2] photocycloaddition of vinylpyridine derivatives. In the liquid-liquid extraction of heavy metal cations, 4 and 5 exhibited high efficiency toward Ag⁺. Comparing the high extractability and complexing stability constant for Ag⁺ to those of the corresponding pyridinocrownophanes 2 and 3 and observing the ¹H NMR spectra in the presence of Ag⁺, the ethereal oxygen atoms and the three nitrogen atoms were found efficiently and cooperatively to act as ligating sites.     

Fluorescent chemosensor for Cu2+ ion based on iminoanthryl appended calix[4]arene

Calix[4]arene based podands 1a of cone conformation and 1b of 1,3-alternate conformation possessing imine units and bearing anthracene moieties have been synthesized by a 1 + 2 Schiff base condensation in good yields and examined for their cation recognition abilities towards cations such as lithium, sodium, potassium, nickel, cadmium, copper, zinc, lead, silver and mercury ions by UV–vis and fluorescence spectroscopy. The calix[4]arene derivative 1b shows a selective fluorescence enhancement in presence of Cu²⁺ ions among the various metal ions tested (Li⁺, Na⁺, K⁺, Ni²⁺, Cd²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Ag⁺ and Hg²⁺ ions). The colour of the solution changes from colourless to light yellow in the presence of Cu²⁺ ions. The stoichiometry of the complex formed between 1b and Cu²⁺ was found to be 1:1 as established by Job’s plot.     

Synthesis of crownophanes possessing bipyridine moieties: bipyridinocrownophanes exhibiting perfect extractability toward Ag ion

Novel crownophanes with two bipyridine moieties (bipyridinocrownophanes 1a and 1b) were conveniently prepared by means of intramolecular [2+2] photocycloaddition of vinylbipyridine derivatives. In the liquid-liquid extraction of heavy metal cations, 1a and 1b exhibited perfect selectivity toward Ag⁺ with high efficiency. It was found that the ethereal oxygen atoms and the four nitrogen atoms in 1a and 1b acted as ligating sites, according to the high extractability and complexing stability constant for Ag⁺ compared to those of the corresponding pyridinocrownophanes 4a and 4b. ¹H NMR and ESI-MS analyses suggested that the crownophanes formed a 1:1 complexes with the Ag⁺ ion.