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.     

Comparing π-complexation capabilities of ionic liquids containing silver(I) and copper(I) ions by headspace single drop microextraction in combination with high-performance liquid chromatography

Selective π-complexation capabilities of silver(I) and copper(I) ions can be effectively facilitated in ionic liquids. To understand the effects of environmental factors that influence the π-complexation of these metal ions with analytes, techniques that employ small volumes of ionic liquid that can be readily analyzed are desired. In this study, headspace single drop microextraction coupled with HPLC is used to investigate a diverse set of environmental factors on the metal ion-mediated complexation with aromatic compounds in ionic liquid media. Silver(I) and copper(I) bis[(trifluoromethyl)sulfonyl]imide salts were both studied by dissolving them in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid and employing the mixture as extraction media for aromatic compounds. Water and acetonitrile within the sample solution were observed to interfere with the complexation of silver(I) ions and aromatic compounds, while ethylene glycol and triethylene glycol did not. The temperature and extraction times were optimized to fully facilitate the π-complexation capabilities of metal ions in ionic liquid media. Partition coefficients between the sample headspace and metal ion were determined using a three-phase equilibria model. Although no discernable difference in analyte partitioning between the headspace and ionic liquid solvent was observed, analyte partition coefficients to silver(I) ion tended to be greater compared to copper(I) ion.     

Liquid-liquid extraction of metal ions by the 6-membered N-containing macrocycle hexacyclen

The nitrogen-containing analogue of 18-crown-6, 1,4,7,10,13,16-hexa-azaoctadecane (hexacyclen)] was studied as a reagent for complexation and extraction of some metal ions. It was found that with this reagent and methyl isobutyl ketone, metal ions such as silver(I), mercury(II), copper(II), platinum(II) and palladium(II) can be quantitatively extracted and separated from iron(III) and some other metal ions.     

Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template

Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.     

An infrared study on the chemisorption of tertiary phosphines on coinage and platinum group metal surfaces

The chemisorption of dimethylphenyl-, methyldiphenyl- and triphenylphosphine on evaporated gold, silver, copper, rhodium, iridium, palladium, platinum and nickel surfaces has been studied by means of infrared reflection–absorption spectroscopy (IRAS). Multilayers of physisorbed phosphine are formed on the surfaces of all metals studied except nickel after deposition from dilute toluene solution. The deposition rate varies for different metal surfaces and it is sometimes quite slow. The standard immersion time was 20 h in this study to secure that an equilibrium between the surface and the solution is reached. Several minutes of ultrasonic treatment are required to get rid of the physisorbed phosphine, leaving a very thin layer of chemisorbed phosphine on the metal surface. Most of the absorption bands in IRAS spectra of these thin layers show significant shifts, which are especially large for dimethylphenylphosphine. It is evident that the electron distribution in the entire phosphine molecules is changed and that the chemisorption to the coinage and platinum group metal surfaces is strong. Infrared spectra of coordination compounds of gold(I), silver(I) and copper(I) with dimethylphenyl-, methyldiphenyl- and triphenylphosphine and of the corresponding phosphine oxides have served as reference material for the chemisorbed phosphines. The spectra of the coordination compounds show similar shifts and intensity changes as the IRAS spectra of tertiary phosphines chemisorbed on the coinage and platinum group metals. This suggests that the studied phosphines are as strongly bound to the coinage and platinum group metal surfaces as to the monovalent coinage metal ions known to form very stable complexes with tertiary phosphines.     

Specific extraction behavior of amide derivative of calix[4]arene for silver (I) and gold (III) ions from highly acidic chloride media

25,26,27,28-tetrakis(N,N-diethylaminocarbonylmethoxy)-5,11,17,23-tetrakis(1,1,3,3-tetramethylbutyl)calix[4]arene, a macrocyclic extraction reagent, and p-(1,1,3,3-tetra-methylbutyl)phenoxymethyl-N,N-diethylamide, an acyclic extraction reagent corresponding to the former one, were synthesized to investigate their extraction behavior for silver(I), gold(III), palladium(II), and platinum(IV) from highly acidic solution into chloroform. In the extraction of silver and gold from hydrochloric acid solution, a completely different extraction behavior was observed between these two types of the reagents. The extraction behavior was examined in detail for silver and was found to be dependent on whether silver ion was extracted as a cationic species or a anionic species complexed with chloride ion. This was supported by proton nuclear magnetic resonance study of the calix[4]arene derivative. As a result, the extraction of silver ion with calix[4]arene derivative was very peculiar which was attributable to the fitting between cyclic size of calix[4]arene and ionic radius of silver.     

Preparation and Analytical Application of a New Chelating Ion Exchange Resin Containing Thioglycolic Acid

Starting from copolymerization of acrylonitrile and divinylbenzene by emulsion polymerization technique, a macroporous, crosslinked polyacrylonitrile copolymer was synthesized. The nitrile groups on the copolymer resin were converted into carboxylic acid groups by hydrolysis with strong alkaline solution of sodium hydroxide to obtain the resin matrix with carboxylic acid groups. A new chelating ion exchange resin containing alkylthioglycolate was prepared by esterification of carboxylic acid groups on the resin matrix and thioglycolic acid with 1,6-hexanediol as binding part. After studies of the basic characters, ion exchange ability, exchange rate and acidity of the medium, it was found that the new resin obtaind was highly selective for silver(I), mercury(II), gold(III) and bismuth(III) in acidic-aqueous solution. Separation of these metal ions from each other and concentration of these metal ions from very dilute solution were studied by liquid chromatography using a short column of this new resin. The analytical applications of this new resin are reported.     

Synthesis of imprinted polymer material with palladium ion nanopores and its analytical application

Ion imprinted polymer (IIP) materials with nanopores were prepared by formation of ternary complex of palladium imprint ion with dimethylglyoxime (DMG) and 4-vinylpyridine (VP, functional monomer) and thermally copolymerizing with styrene (crosslinking monomer) and divinylbenzene (cross linker) and 2,2′-azobisisobutyronitrile as initiator. The synthesis was carried out with cyclohexanol as porogen and subsequently leached with 50% (v/v) HCl to obtain leached IIP particles. These leached IIP particles can now pick up palladium ions from dilute aqueous solutions. The optimal acidity for quantitative enrichment was 0.2-0.4N HCl and eluted completely by stirring for 15 min with 2×10 ml of 50% (v/v) HCl. The palladium ion imprinting polymer gave 100 times higher distribution ratio than ion recognition (blank) polymer (IRP). Further, percent extraction, distribution ratio and selectivity coefficients of palladium and other selected inorganic ions using IRP and IIP particles were determined and compared. Five replicate determinations of 50 μg of palladium in 1 l of solution gave a mean absorbance of 0.200 with a relative standard deviation of 2.12%. The detection limit corresponding to three times the standard deviation of the blank was 2.5 μg of palladium/l.     

Cation-exchange behaviour of the platinum group and some other rare elements in hydrobromic acid-thiourea-acetone media

Ion-exchange distribution coefficients and elution curves are presented for copper(I), silver, gold(I), palladium, platinum(II), rhodium(III), iridium(III), ruthenium(III), osmium(III), mercury(II), thallium(I), tellurium(II), lead and bismuth in mixtures of thiourea, hydrobromic acid, acetone and water, with the cation-exchange resin AGW50W-X4. The system affords excellent separations of rhodium, mercury, silver (or copper), tellurium, gold, and palladium (or platinum) from each other.     

Study on the interaction of platinum(IV), gold(III) and silver(I) ions with DNA

Fluorescence, absorption spectra have been produced by the interaction of platinum(IV), silver(I) and gold(III) ions with the berberine–DNA system (berberine, Scheme 1). Platinum(IV) and gold(III) ions show different effects from that of silver(I) ion on the spectral characteristics of the berberine–DNA system. Quenching fluorescence is seen with platinum(IV) and gold(III) ions addition, whereas increasing fluorescence is observed for silver(I) ions. The addition of gold(III) and silver(I) ions cause an increase in absorption of the berberine–DNA system. The above results suggest that different metal ions exhibit different affinities when binding to DNA correlates well with the ions’ charge, structure and the coordination ability.     

Metal ion capillary zone electrophoresis with direct UV detection: Separation of metal cyanide complexes

Mixtures of cyanide complexes of iron(III), copper(I), iron(II), nickel(II), chromium(III), mercury(II), palladium(II), silver(I), cadmium(II), zinc(II), cobalt(II), and cobalt(III) have been separated by capillary zone electrophoresis using a fused silica capillary and 20 mM phosphate buffers containing 1–2 mM sodium cyanide. The complexes were detected by direct UV absorpticn at 214 nm; detection limits are in the mid ppb range for all metals except cadmium and zinc. The different detectability of various metal cyanide complexes enables the application of the method to the analysis of complex matrices such as cyanide plating bath solutions.     

Polythiophene-coated Fe3O4 nanoparticles as a selective adsorbent for magnetic solid-phase extraction of silver(I), gold(III), copper(II) and palladium(II)

We have developed a fast method for sensitive extraction and determination of the metal ions silver(I), gold(III), copper(II) and palladium(II). Fe₃O₄ magnetic nanoparticles were modified with polythiophene and used for extraction the metal ions without a chelating agent. Following extraction, the ions were determined by flow injection inductively coupled plasma optical emission spectrometry. The influence of sample pH, type and volume of eluent, amount of adsorbent, sample volume and time of adsorption and desorption were optimized. Under the optimum conditions, the calibration plots are linear in the 0.75 to 100 μg L^?1 concentration range (R²?>?0.998), limits of detection in the range from 0.2 to 2.0 μg L^?1, and enhancement factors in the range from 70 to 129. Precisions, expressed as relative standard deviations, are lower than 4.2 %. The applicability of the method was demonstrated by the successful analysis of tap water, mineral water, and river water.

大孔聚丙烯醛-呋喃-2-硫代酰腙螯合树脂的合成及其性能的初步研究

合成了一新型高分子骨架，大孔内烯醛－苯乙烯－二乙烯苯三元共聚物树脂骨架，通过其含有的活泼醛基与呋喃－2－硫代酰肼螯合剂进行高分子反应，制备了一种含氮、硫配位原子的螯合树脂，聚丙烯醛－呋喃－2－硫代酰腙。对其与贵金属离子的吸附性能进行了初步研究，结果表明，该树脂对金、钯及铂具有选择性吸附作用，吸附容量分别为1.20mmol/g干树脂，0.37mmol/g干树脂及0.28mmol/g干树脂。     

Host-guest assembly of ligand systems for metal ion complexation. Synergistic solvent extraction of copper(II) and silver(I) by 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclodecane in combination with carboxylic acids

Host-guest formation between 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclodecane (1) and lipophilic organic carboxylic acids in chloroform has been investigated and the effect of such ligand assembly on the solvent extraction of copper(II) and silver(I) has been probed. NMR titration experiments in the absence of a metal ion confirm the formation of weak 1:1 and 1:2 (macrocycle:carboxylic acid) assemblies in CDCl(3) between 1 and palmitic (hexadecanoic) acid or 4-tert-butylbenzoic acid while difunctional salicylic acid showed a 1 [ratio] 2 interaction that is somewhat stronger. The interaction between the former two acids and the tetra-N-benzylated macrocycle is significantly less than that reported previously for its non-substituted parent, cyclam; a result that likely reflects the presence of the less-basic, more sterically hindered tertiary nitrogens in 1 relative to the secondary nitrogens present in cyclam. Carboxylic acid-containing assemblies of this type have been used as extractants in a series of solvent extraction (water/chloroform) experiments. From both previous observations as well as from entropy considerations, it was anticipated that the use of a host-guest assembly of the above type for metal-ion complexation might contribute to enhanced metal ion binding (and concomitant enhanced metal ion extraction). Such behaviour is postulated to arise from the components of the coordination sphere being, at least in part, assembled for complex formation. In accord with this, the use of the ligand assembly involving palmitic acid/macrocycle 1 was found to lead to enhanced (synergistic) extraction of copper(II) at a metal ion concentration of 10(-3) mol dm(-3) while, for silver(I), synergism was somewhat marginal at this concentration but was clearly apparent under related conditions when the silver concentration was reduced to 10(-4) mol dm(-3). Similar behaviour towards silver was also observed when 4-tert-butylbenzoic acid was substituted for palmitic acid, while the use of salicylic acid resulted in enhanced (synergistic) extraction at both metal ion concentrations.     

Reactions of anionic porphyrin with group 11 elements: a spectrophotometric and electrospray ionization mass spectrometry study

The reaction of 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I (CPI) with the elements of 11 group have been studied. CPI is an anionic porphyrin that slowly reacts with copper ion to form Cu^IICPI and with silver ions to form Ag^IICPI, Ag^IIICPI complexes and colloidal silver. Gold ions do not form complexes with CPI, but, in the main, colloidal gold and some CPI-N-oxide. The kinetics of the reactions with copper and silver were spectrophotometerically studied and the rate constants were calculated. The identification and characterization of this water-soluble anionic porphyrin and its metal complexes have been performed by electrospray mass spectrometry (ESI-MS) that proved to be an excellent method for these determinations. The multiple charged parent ions for metal free ligand and their metal complexes were identified.     

多烷基支链仲胺从碱性氰化液中萃取金

研究了多烷基支链促胺从碱性氰化液中萃取金,考察了平衡时间、水相初始pH值、金浓度、离子强度、温度、萃取剂浓度、稀释剂、相比等因素对金萃取率的影响,绘制了萃取等温线,测定了金的饱和容量,考察了萃取体系对银（Ⅰ）、铁（Ⅱ）、铜（Ⅰ）、镍（Ⅱ）、锌（Ⅱ）的萃取性能,计算出了金与这些杂质元素的分离系数,研究了负载有机相中金的反萃,结果表明,该萃取体系在pH5－11范围内对Au（CN）2^－有较高的萃取率和选择性,pH1／2＝11.7,可用于碱性氰化液中金的萃取分离。     

Novel chiral bisoxazoline ligands with a biphenyl backbone: preparation, complexation, and application in asymmetric catalytic reactions

Novel C(2)-symmetric chiral bisoxazoline ligands 1 were easily prepared from enantiomerically pure 2-amino alcohols and achiral 2, 2'-biphenyldicarboxylic acid via the corresponding amide and mesylate as intermediates. Since these ligands bear only two ortho-substituents on the biphenyl backbone, the biphenyl axis is not fixed, and the two diastereomers of these ligands exist in equilibrium in solution. Interestingly, when the ligands 1 were coordinated with a metal ion, only one of the two possible diastereomer complexes, an (S,aS,S)-complex, can be formed depending on the combination of the ligand and the metal ion. Thus, copper(I) afforded only the (S,aS,S)-complexes with all ligands 1, while zinc(II), palladium(II), and silver(I) afforded the (S,aS, S)-complexes as the sole product only with 1b, which has a bulky tert-butyl group on the oxazoline ring, and a mixture of the two diastereomer complexes with 1a,c,d. The copper(I)-catalyzed asymmetric cyclopropanation of styrene with diazoacetate proceeded successfully with these ligands and good to excellent enantioselectivities were afforded.     

Simultaneous extraction and preconcentration of copper,silver and palladium with modified alumina and their determination by electrothermal atomic absorption spectrometry

In the present work,an easy solid phase extraction method using alumina modified with polyethylenimine as a new adsorbent was applied to the simultaneous extraction of copper,silver,and palladium ions prior to their determination with electrothermal atomic absorption spectrometry.The analytical procedure involved the complex formation of these cations with polyethylenimine as a chelating agent in buffer media of pH 7.0.Under the optimum conditions,a preconcentration factor of200,150,and 200,precision of ±5.4%,±4.7%,and ±5.2%and linear calibration ranges of 15.0-140,4.0-93,and 7.5-125 ng/L(in original solution) for Cu,Ag,and Pd were obtained,respectively.Also detection limits of3.9,1.1,and 2.0 ng/L were obtained for Cu,Ag,and Pd,respectively.The proposed method was applied to the determination of copper,silver,and palladium in some real samples with satisfactory results.     

Preparation and analytical properties of a chelating resin containing cysteine groups

A macroporous, cross-linked polyacrylonitrile copolymer was synthesized, the nitrile groups were converted to carboxylic acid by hydrolysis, and these carboxylic acid groups were treated with L-cysteine and 1,6-hexanediol (binding agent). Studies of the basic characteristics of this resin showed that it was highly selective for silver(I), mercury(II), gold(III) and platinum(IV) in aqueous acidic solution, the maximum capacities being 0.97, 0.65, 1.22 and 0.39 mmol g^-1 of dry resin, respectively. These four metal ions can be separated from each other, or concentrated from very dilute solutions, on a short column of the resin. The effects of different acids and of various common metal ions are reported.     

Functionalized di- and tetrathia-crowns and their use to quantitatively separate and recover gold(III), palladium(II), silver(I) and mercury(II) Ions

Two new dithia-crowns containing a hydroxy group and 1,4,7,10-tetrathia-18-crown-6 containing an allyl-oxymethyl substituent were prepared in good yields. Two of these crowns were covalently attached to silica gel. The silica gel-bound thia-crowns were used to separate gold( III ), palladium( II ), silver( I ) and mercury( II ) ions from an aqueous 0.1 M nitric acid solution which also contained 1.0 M ferric chloride.