Studies on the thermal decompositions of As-triazine derivatives and their compounds with metal ions

The thermal decompositions of the new complex salts of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 5,6-diethoxyearbonylmethyl-3-seleno-1,2,4-triazine (HSeTEK) and 5,6-diethoxycarbonylmethyl-3-thio-1,2,4-triazine (HTTEK) were investigated on the basis of the respective thermal curves. The thermoanalytical investigations indicate that HSeTEK, HTTEK, and their complexes with metal ions all undergo three-stage changes as the temperature is raised. The stages of pyrolysis established from the thermal data were compared, and the rates and stages of pyrolysis were related to the structures of the compounds.

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Zusammenfassung Die thermische Zersetzung der neuen Komplexsalze von Mn(II), Co(II), Ni(II) und Cu(II) mit 5,6-Diäthoxycarbonylmethyl-3-seleno-1,2,4-triazin (HSeTEK) und 5,6-Diäthoxycarbonylmethyl-3-thio-1,2,4-triazin (HTTEK) wurden auf der Grundlage der entsprechenden thermischen Kurven untersucht. Die thermoanalytischen Untersuchungen zeigen, daß HSeTEK, HTTEK und deren mit Metallionen gebildeten Komplexe bei Temperaturerhöhung einer jeweils dreistufigen Umwandlung unterliegen. Die auf der Basis der thermischen Daten festgestellten Pyrolysestufen wurden verglichen und Geschwindigkeit und Abschnitte der Pyrolyse mittels der Struktur der Verbindungen erläutert.

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, , 5,6- -3--1,2,4- 5,6 5,6 -3--1,2,4-. , . . - .

     

Preparation of amidoxime-modified polyacrylonitrile (PAN-oxime) nanofibers and their applications to metal ions adsorption

Polyacrylonitrile (PAN) nanofibers were applied to metal adsorption. PAN nanofibers (prepared by an electrospinning technique) were chemically modified with amidoxime groups, which are suitable for metal adsorption due to their high adsorption affinity for metal ions. The adsorption of the amidoxime-modified PAN (PAN-oxime) (25% conversion) nanofibers followed Langmuir isotherm. The saturation adsorption capacities for Cu(II) and Pb(II) of 52.70 and 263.45 mg/g (0.83 and 1.27 mmol/g), respectively, indicating that the monolayer adsorption occurred on the nanofiber mats. In addition, over 90% of metals were recovered from the metal-loaded PAN-oxime nanofibers in a 1 mol/L HNO₃ solution after 1 h.     

Binding of metal ions to melanin and their effects on the aerobic reactivity

The binding of Mg(II), Ca(II), Zn(II), Cu(II) and Fe(III) to ETDA-washed Sepia melanin is quantified by inductively coupled plasma mass spectrometry. By monitoring the solution pH change associated with metal uptake, it is concluded that Mg(II), Ca(II) and Zn(II) bind to carboxylic acid groups in melanin, Cu(II) binds to hydroxyl (OH) groups and Fe(III) binds to OH or amine groups. The aerobic reactivity of melanins with different metal contents is analyzed by examining their ability to cause strand breaks in supercoiled pUC18 DNA. Cu(II)- and Fe(III)-enriched melanins induce the most damage. Hydroxyl radical, *OH, is proposed to be one of the reactive oxygen species responsible.     

Ligand-accelerated liquid membrane extraction of metal ions

A method has been developed to enhance the liquid membrane extraction of heavy metals such as cobalt, copper and nickel. The method consists of introducing anion ligands, such as acetate, to the aqueous solution containing metal ions. In the absence of a ligand in the aqueous phase, it takes about 15 min for a 80% cobalt recovery, while only 2 min are needed for a 95% recovery with the addition of 0.1 M acetate in the feed solution. The ligand effects on liquid membrane extraction are rationalized in terms of the labile nature of the ligand—metal complexes, the distribution coefficients of the metal ions, the interfacial and surface tensions, and by the nuclear magnetic r̀esonance (NMR) spectra of the metal—organic complexes.     

含卤素杯[4]芳烃衍生物的合成及其对金属离子的萃取性能

以对叔丁基苯酚为原料,经逐步反应在对叔丁基杯[4]芳烃的下缘引入含卤素的基团,得到了一系列含卤素的杯[4]芳烃衍生物(记为1,2,3,4);利用核磁共振谱和气相色谱-质谱证实了目标产物的结构;并评价了产物对水中的Cr3+、Cu2+、Ag+的萃取性能.结果表明:杯[4]芳烃衍生物2、3和4分别对Cr3+、Cu2+和Ag+具有较好的萃取效果.     

Magnetic metal-organic frameworks for the extraction of trace amounts of heavy metal ions prior to their determination by ICP-AES

Microchimica Acta - The authors describe the preparation of two kinds of metal-organic frameworks (MOFs), referred to as TMU-8 and TMU-9. The MOFs were applied to the preconcentration of the ions...     

The application of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane to the extraction of metal ions

The use of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Tet) in chloroform solutions provides quantitative extraction of lead(II), cadmium(II), copper(II) and zinc(II) at different pH values from solutions containing perchlorate and cyclohexanecarboxylic acid. Nickel(II) and cobalt(II) ions are not extracted quantitatively. Single extractions of mixtures of copper with transition metals gave the best separations for the copper/nickel system. Separations of copper from cobalt, lead, manganese and iron were less satisfactory.     

Solvent extraction of several metal ions with mercaptotropone

Mercaptotropone was synthesized from tropone, and its acid dissociation constant (K_a) and distribution coefficient (K_D) between benze and aqueous solution were spectrophotometrically determined as 5.75 (pK_a) and 2.46 (log K_D); Extraction behaviour of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cr(III), Fe(III), Y(III), and Zr(IV) with this reagent into benzene was examined. Cu(II) and Fe(III) were completely extracted from acidic solution, Mn(II), Co(II), Ni(II), Zn(II), Pb(II), and Zr(IV) were also extracted from intermediate pH region, a part of Cr(III) was extracted, but Y(III) was not extracted.     

表面活性剂体系萃取分离贵金属离子的研究

研究了在TritonX 100 (NH4)2SO4 络合剂体系中,贵金属离子的萃取分离行为。考察了金属络合物的液 液两相间的分配行为及影响络合物萃取行为的各种因素,优化了萃取分离条件。实验结果表明,在pH7.0～7.5的溶液中,络合剂PAR能与Pd(Ⅱ)形成稳定的络合物,可被定量萃取,实现了Pd(Ⅱ)与Pt(Ⅵ)、Ir(Ⅵ)、Mo(Ⅵ)等混合离子间的定量分离。混合离子分离中,Pd(Ⅱ)的回收率为97.5%～100.8%。     

The color reactions of sulfonazo-III isomers with lanthanum and alkaline earth metal ions

Six sulfonazo-III isomers were synthesized, and their color reactions with alkaline earth metals and lanthanum investigated. All six reagents had good sensitivities for lanthanum (? = 1.9–5.0·10⁴), but the sensitivities for alkaline earth metals were fairly low except for the barium chelate of sulfonazo-III (? = 2.8 · 10⁴). The position of the sulfo group on the phenyl ring and the symmetry of the reagent are important for the barium reactions, but of little significance for the lanthanum reactions. The effects of water-miscible solvents are also described.     

Dendritic effects of crown ether-functionalized dendrimers on the solvent extraction of metal ions

The ability of a series of crown ether-functionalized dendrimers to function as alkali metal picrate extraction agents is assessed by liquid-liquid extraction and ¹H NMR titration experiments. Crown ether-functionalized dendrimers that contain Fréchet-type poly(benzyl ether) dendrons of different generation as building blocks display different extraction characteristics toward alkali metal cations. Positive and negative dendritic effects depending on the generation of the dendrimer are assigned in the complexation behaviour of the dendritic host compounds.     

Solvent extraction of alkali metal ions with chromium complexes

Solvent extraction of alkali metal ions by batch and counter-current distribution methods was investigated with tetrathiocyanatodiamminechromate(III) and tetrathiocyanatodianilinechromate(III) as reagents and nitromethane and nitrobenzene as organic solvents. The distribution ratios of alkali metal ions in the various systems were measured. Cesium was readily extracted with the aniline compound and nitrobenzene. The separation of sodium from potassium in trace amounts was possible by the counter-current distribution method.     

Solid phase extraction of metal ions using carbon nanotubes

The sorption behaviour of carbon nanotubes (CNTs) toward some divalent metal ions such as Cu(II), Co(II), Ni(II), Zn(II), Pb(II), Mn(II) and Cd(II) has been investigated systematically. The affinity order of the metal ions towards CNTs at pH in the range of 7.0-9.0 was: Cu(II) > Pb(II) > Zn(II) > Co(II) > Ni(II) > Cd(II) > Mn(II). The experimental parameters for preconcentration of copper, which exhibits the highest affinity towards carbon nanotubes, on a microcolumn packed with CNTs prior to its determination by flame atomic absorption spectrometry have been investigated. Copper can be quantitatively retained at pH 8.2 from sample volume up to 150 mL and then eluted completely with 0.1 mol L^− 1 HNO₃. The limit of detection limit for Cu(II) determination with FAAS detection was 2.1 μg L^− 1, and the RSD was 3.5% at the 50 μg L^− 1 level. Under the optimal conditions for copper enrichment also Zn(II), Pb(II) and Ni(II) could be quantitatively preconcentrated from water samples. The method was validated using a certified reference materials BCR-610 and SRM 1640.     

Selective extraction of metal ions associated with humic acids

The ability of a range of electrolyte solutions to release metal ions (Cu, Pb, Cd, Zn) presorbed on two samples of humic acid has been investigated. Though treatment with mineral acid or a chelating agent released a high proportion of the retained metal ion, recoveries were never total. Concentrated salt solutions displaced about 80% of the retained Cd or Zn, and about half of any Cu or Pb held by the organic matter, which indicates that most of the adsorbed metal ion is exchangeable, the extraction efficiency being controlled by competing equilibria. The effect of added clay suspensions was also examined. Analytical procedures for fractionating the total metal content of soils into subgroups have been assessed against the observed extraction behaviour.     

Liquid-liquid extraction of group IB metal ions by thioethers

Liquid-liquid extraction of metal ions by means of organic extractants possessing divalent sulfur (thioethers) is discussed. it is shown that 1,2-bis(hexylthio)ethane (BHTE) and 13,14-benzo-1,4,8,11-tetrathiacyclopentadecane (TTX) are powerful extractants for soft metal ions such as copper(I), Silver(I), and gold(I). The same is true for the trivalent phosphorus compounds, triphenylphosphine and phosphite tristers, which were studied for comparison. Copper(II) and gold(III) are efficiently extracted with thioethers in combination with reducing agents. From an equilibrium study for the extraction of copper(I) and silver(I) by BHTE (L), a complex of the type ML₂X (M⁺, metal ion; X^?, anion) was proved to be extracted. In the extraction of gold, the combined use of a thioether and phosphite enhanced the extractability of the metal, compared with the independent use of these extractants; the synergism is discussed. Further, the reductive extractions of copper(II) and gold(III) were coupled with a photo-redox reaction, leading to light-induced extraction of these metal ions.     

Synthesis of N-substituted cyclic triglycines and their response to metal ions

N,N^′,N^″-Trisubstituted-cyclo-triglycines were synthesized. The major conformation of these compounds has C₃ symmetry, and the carbonyl groups and substituents on the nitrogen are inclined in the same direction. Their response to various metal ions was estimated by constructing ion-selective electrodes. Two of them responded selectively to Ca²⁺ over other cations, demonstrating that N,N^′,N^″-trisubstituted-cyclo-triglycines provide a new scaffold to act as host molecules.     

Solvent extraction of metal ions by use of Schiff bases

Schiff bases are aldehyde or ketone like compounds in which the carbonyl group is replaced by imine or azomethine group. They are widely used for industrial purposes and also exhibit a broad range as extractants. A general view of solvent extraction applications of complexes is discussed in this review. The family of Schiff bases and their extraction of various transition metals such as Co, Cu, Cr, Fe, Ga, Hg, Mn, Mo and Ni are discussed. A brief history of the synthesis and reactivity of Schiff bases will be presented. Factors on solvent extraction will be illustrated and discussed.     

Schiff碱二价金属离子配合物的合成及抗菌性

氨基酸、肽、蛋白质、酶等生物大分子中半光氨酸残基上的硫原子与一些过渡金属离子形成的配合物具有特殊的生物活性,因此配体和配合物的研究一直受到人们的重视[1,2]。我们设计并合成出的乙酰基硫代甲酰取代苯胺缩氨基脲Schiff碱具有与这些生物大分子相同的配位原子,可以作为研     

Perfluorocarbon-based liquid-liquid extraction for separation of transition metal ions.

We report a liquid-liquid extraction system based on perfluorocarbon (fluorous-solvent extraction) that allows selective extraction of metal ions from aqueous and organic phases to a perfluorocarbon phase (FC-72) with perfluorinated beta-diketone (1,1,1,5,5,6,6,6-octafluoro-2,4-hexanedione), which can be followed by backward extraction using 1 M nitric acid.