Rational ligand design for metal ion recognition. Synthesis of a N-benzylated N2S3-donor macrocycle for enhanced silver(I) discrimination

Four previously documented ligand design strategies for achieving Ag(I) discrimination have been applied to the design of a new N-benzylated N2S3-donor macrocycle; the latter shows high selectivity for Ag(I) over Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) in log K and bulk membrane transport studies.     

Synthesis and spectral studies of transition metal complexes with 1,5:11,15-dimetheno-2,4,10,12-tetramethyl-[1,5,9,13]-tetraazahexadeca-1,3,5,6,10,11,13,15,16,20-decene a sixteen-membered tetradentate macrocyclic ligand

Complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Pd(II), Pt(II), Ru(III) and Ir(III) with a sixteen-membered 1,5:11,15-dimetheno-2,4,10,12-tetramethyl-[1,5,9,13]-tetraazahexadeca-1,3,5,6,10,11,13,15,16,20-decene macrocyclic ligand have been synthesized. These complexes are characterized by magnetic moment, infrared, electronic, EPR and mössbauer spectral studies. All of complexes were found to have six-coordinated octahedral geometry and are of the high spin type except for the Pd(II) and Pt(II) complexes which are four coordinate, square planar and diamagnetic.     

Metal ion complexing properties of dipyridoacridine, a highly preorganized tridentate homologue of 1,10-phenanthroline

DPA (dipyrido[4,3-b;5,6-b]acridine) may be considered as a tridentate homologue of phen (1,10-phenanthroline). In this paper some of the metal ion complexing properties of DPA in aqueous solution are reported. Using UV-visible spectroscopy to follow the intense π-π* transitions of DPA as a function of pH gave protonation constants at ionic strength (μ) = 0 and 25 °C of pK(1) = 4.57(3) and pK(2) = 2.90(3). Titration of 10(-5) M solutions of DPA with a variety of metal ions gave log K(1) values as follows: Zn(II), 7.9(1); Cd(II), 8.1(1); Pb(II), 8.3(1); La(III), 5.23(7); Gd(III), 5.7(1); Ca(II), 3.68; all at 25 °C and μ = 0. Log K(1) values at μ = 0.1 were obtained for Mg(II), 0.7(1); Sr(II), 2.20(1); Ba(II), 1.5(1). The log K(1) values show that the high level of preorganization of DPA leads to complexes 3 log units more stable than the corresponding terpyridyl complexes for large metal ions such as La(III) or Ca(II), but that for small metal ions such as Mg(II) and Zn(II) such stabilization is minimal. Molecular mechanics calculations (MM) are used to show that the best-fit M-N length for coordination with DPA is 2.60 ?, accounting for the high stability of Ca(II) or La(III) complexes of DPA, which are found to have close to this M-N bond length in their phen complexes.     

High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water

γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.     

A Selective Electrochemical Sensor for the Detection of Cd(II) Based on a Carbon Paste Electrode Impregnated with a Novel Ion-imprinted Hybrid Polymer

An electrochemical sensor (CPE-IIHP) was developed for Cd(II) using a carbon paste electrode (CPE) impregnated with an ion-imprinted hybrid polymer (IIHP). A CPE-NIHP was also prepared for comparison. DPASV was used to optimize the sensor response and quantify Cd(II). The sensor presented a wide linear range from low concentrations of Cd(II): 1 to 100 μg L⁻¹ and high concentrations of Cd(II): 2.75 to 5.0 mg L⁻¹. Ions such as Co(II), Pb(II), Ni(II), Zn(II), Fe(II), Fe(III), Sn(II) and Cu(II), showed no variation in the Cd(II) signal. The CPE-IIHP was successfully applied in river and drinking water analysis, revealing the great potential for its application.     

Thin Layer and Paper Chromatographic Separations of d-Block Cations Complexed with ANILS

Abstract

Diverse binary, ternary and quaternary mixtures of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Au(III) d-block cations complexed with p-dimethylamino- and p-diethylamino- anils of thiopheneglyoxal have been separated by thin layer and paper chromatographic techniques. But quantitative separations have been done by thin layer chromatography, on account of wide difference in migration rates and high compectedness of complexes on gel layers. Chromatogram fragments visualised as such have been estimated spectrophotometrically.     

A chelating polymer resin: synthesis,characterization, adsorption and desorption performance for removal of Hg(II) from aqueous solution

A chloromethylated polystyrene-N-methyl thiourea chelating resin (DMTUR) was successfully prepared by the reaction of chloromethylated polystyrene beads (PS-Cl) with N-methyl thiourea (DMTU). The DMTUR exhibited a high selective adsorption toward Hg(II) in the mixture of different metal ions containing Cu(II), Hg(II), Cd(II), Pb(II), Cr(III) and Ni(II), and the adsorption capacity of Hg(II) approached a maximum with a value of 347 mg/g at pH = 4.0. Moreover, the batch kinetic study showed that the adsorption behavior of Hg(II) presented as a pseudo-second-order manner. And the adsorption isotherms fitted well with Langmuir model, and the maximum uptake of Hg(II) could reach to be 476 mg g^?1 at 35 °C. The thermodynamics study ensured the adsorption process essentially as favorable and endothermic. Finally, an eluent of 4 M HNO₃ solution could completely remove the adsorbed Hg(II) and the adsorption capacity allowed a high level at least five cycles. As aforementioned appealing properties, the DMTUR with simple technology, high adsorption capacity, significant selectivity and good regenerability may have a potential application in industrial scale as a treatment of enriched Hg(II) in wastewater.     

Preparation, characterization, and application of a new thiol-functionalized ionic liquid for highly selective extraction of Cd(II)

A highly selective thiol-functionalized ionic liquid (thiol-FIL) was synthesized and characterized by FT-IR and ESI mass spectroscopy. The capability of thiol-FIL to extract Cd(II), Ni(II), Cr(III) and Pb(II) was evaluated. It is found that thiol-FIL possesses high selectivity for Cd(II), and this has led to a method for determination of Cd(II) by flame atomic absorption spectrometry that is free of interferences by up to a 1,000-fold excess of Na(I), Mg(II), Ca(II), Mn(II), Fe(III), Al(III), Cu(II), Zn(II), Ni(II), Cr(III), Co(II), As(III), Pb(II), and Hg(II). With extraction equilibrium time of 1 min, a good linearity (r = 0.9998) and a detection limit of 0.39 μg?L^?1 were obtained. The precision (RSD) for 11 replicate measurements of 10 μg?L^?1 Cd was 1.6%. The method was validated using certified reference materials. The recoveries of cadmium in spiked real samples ranged from 97% to 102%.     

Multielement preconcentration of trace metals from natural waters by solvent extraction with an alkylated oxine derivative

Kelex 100, a commercially available alkylated oxine derivative, is shown to be effective, in purified form, for the simultaneous extraction of trace levels of Cd(II), Co(II), Cu(II), Mn(II), Ni(II), Pb(II), and Zn(II) from natural waters into toluene. The high lipophilicity of the extractant and its chelates affords large preconcentration factors in a single batch-extraction. Back-extraction with a small volume of nitric acid provides additional enrichment for subsequent determination of total (soluble) metal by graphite-furnace atomic-absorption spectrometry (GFAAS). Calibration with standard solutions can be used, which has advantages over the method of standard additions.     

含亚硫酸乙烯酯和碳酸乙烯酯功能基树脂的合成及其对贵金属离子的选择吸附性

制备了高功能基转化率的孪二羟基树脂,由此合成了含亚硫酸乙烯酯功能基(2.30毫摩尔/克树脂)和碳酸乙烯酯功能基(2.57毫摩尔/克树脂)的树脂4和5。在酸度范围内树脂4选择吸附Pt(Ⅱ),两者对Au(Ⅲ) 有高选择吸附性,而很少吸附共存的Pd(Ⅱ)、Pt(Ⅳ)及铁、钴、镍、铜、锰、锌、铅、镉等二价金属离子。树脂4对金的吸附容量为126(毫克 Au(Ⅲ)/克树脂),分配系数Kd为824(毫升/克),一次洗脱率达85％。树脂5的吸附容量为46.0(毫克 Au(Ⅲ)/克树脂),Kd为84.1(毫升/克)。两种树脂吸附Au(Ⅲ)的速率T_(1/2)分别为1、0.8小时.     

Micellar chromatographic separation of vanadium(V) chelate with 2-(2-thiazolylazo)-5-dimethylaminophenol

Summary In reversed phase—high performance liquid chromatography for metal chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol, an aqueous non-ionic surfactant solution is used as a mobile phase. Among V(V), Fe(III), Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Mn(II), and Al(III), only the V(V) chelate gave a resolved peak by using 0.8% w/w poly(oxyethylene)_n-4-nonylphenyl ether (n=20) solution buffered at pH 3.8. V(V) can be selectively separated and sensitively determined.     

Separation and determination of trace amounts of beryllium(II), aluminium(III) and chromium(III) with chromotrope 2C chelates by RP-HPLC

A reversed-phase high-performance liquid chromatographic separation and determination of beryllium(II), aluminium(III) and chromium(III) with chromotrope 2C chelates on a C18-bonded stationary phase is reported. Methanol-water (45:55 v/v) containing 6 x 10(-3)M tetra-n-butylammonium bromide (TBAB) and 2 x 10(-2)M acetate buffer solution (pH 6.0) as mobile phase and with spectrophotometric detection at 530 nm was applied. The method has high sensitivity, the detection limits being 0.2 ppb for beryllium(I), 1 ppb for aluminium(III) and 2 ppb for chromium(III). Under the optimum conditions, most other metal ions did not interfere, e.g. up to 2 mg of Hg(II), Sn(II, IV), Pb(II), Bi(III), Ag(I), Zn(II), Cd(II), Cu(II), 1.5 mg of Fe(II), Co(II), Ni(II), 1.2 mg of Ca(II), Mg(II), Sr(II), Ba(II), 1 mg of Ga(III), In(III), 0.5 mg of Fe(III), 1 mg of Ga(III), In(III), 0.5 mg of Fe(III), 0.4 mg of Th(IV), Zr(IV). The method can be applied to the simultaneous determination of trace amounts of beryllium(II), aluminium(III) and chromium(III), in water, rice, flour and human hair samples.     

Synthesis and properties of a chelating resin containing triazolethiol groups

A macroreticular poly(acrylic acid)-based resin with triazolethiol as the functional group has been synthesized. The stability of the resin in acidic media and the behaviour in sorption and desorption of various metal ions have been investigated and compared with those of the acylthiosemicarbazide resin which is an intermediate in synthesis of the triazolethiol resin. Both resins show high affinity for copper(II) silver, cadmium and mercury(II), and high selectivity for silver and mercury(II) at low pH (1–2), and even at pH 7 if EDTA is present. The triazolethiol resin sorbs metal ions faster than the acylthiosemicarbazide resin does and sorbs mercury(II) from high concentrations of acids and neutral salt solutions. This resin has been applied to the concentration of silver and mercury(II) from sea-water samples by column operation.     

Reversed-phase HPLC separation of complex mixtures of trace metals as dibenzyldithiocarbamate chelates

The dibenzyldithiocarbamate chelates of Cd(II), Pb(II), Bi(III), Hg(II), Ni(II), Cu(II), As(III), Fe(III), Co(III) and In(III) are separated by reversed-phase HPLC in isocratic conditions. The procedure is simple, rapid, and gives satisfactory separations with high efficiency and sensitivity at mobile phase compositions very rich in organic modifier (85-88% CH(3)CN). The detection limits range from 1.4 to 14 mug/1. The elution order is correlated with the ability of the central metal atom to affect the electronic distribution of the ligand, which has readily polarizable donor atoms. Infrared spectroscopy data corroborate this assumption.     

Application of an imidazoline group-containing chelating fiber for the determination of trace noble metals in superhigh-temperature alloys

An imidazoline group-containing chelating fiber was prepared by means of the reaction of nitrile groups with ethylenediamine in an hydrazine-modified polyacrylonitrile fiber. The adsorption properties of the chelating fiber for Au(III), Pd(II), Pt(IV), Ir(IV), Os(IV), Rh(III) and Ru(IV) ions, such as binding capacity, distribution coefficient, sorptive rate and quantitative elution of Au(III), Pd(II) and Pt(IV) ions were investigated. The imidazoline group-containing chelating fiber possessed high binding capacities and good adsorption kinetic properties, exhibited high affinity for noble metals in 0.1-1.0 mol/L HCl and could be efficiently re-used. After the separation of trace Au(III), Pd(II) and Pt(IV) ions from a matrix using the chelating fiber, these ions could be determined by ICP-AES with satisfactory results, and the relative standard deviation for Au(III), Pd(II) and Pt(IV) ions was less than 6%.     

The Stability Constants of Complexes of BDBPH- Metals and Species Distributions

The study on the design and synthesis of model compounds for metalloproteins has been a subject of extensive investigation1. During the last decade, a number of synthetic structural models for some kinds of metalloproteins with several types of ligands have been reported in literature2,3,4. We have recently reported a new 24-membered hexaazadiphenol macrocyclic ligand, 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo [23,3,1,111,15] triaconta-1 (28),11,13,15 (30),25,26-hexaene,…     

Liquid extraction of noble metal ions with bis(α-aminophosphonates)

Extraction of Au(III), Pt(IV), and Pd(II) ions from hydrochloric acid media with solutions of two bis(aminophosphonates), such as N,N-bis(dipentoxyphosphorylmethyl)octylamine and N,N′-bis[[(dioctyloxyphosphoryl)methyl]butylamine], in chloroform and xylene was investigated. Both these extractants proved to be highly effective for Au(III) ions in a wide acidity range, which allows these ions to be separated from other noble metal ions with a high degree of selectivity. At the same time, Pt(IV) and Pd(II) ions cannot be separated from one another with the extractants studied. The selectivity of their separation from Fe(III), Cu(II), Co(II), and Ni(II) metal ions is, too, not high. The reasons for these results lie in the specific structural features of the extractants, which predetermine the extraction mechanism.     

Synthesis of hydrothioxanthenes. II

Ethylenedicyclohexanone and phosphorus pentasulfide give 9-methyloctahydrothioxanthene (II) (yield ～37%), a small amount of 9-methylperhydrothioxanthene (IV) (～2%), and 9-methylthioxanthene (VI) (～1%). Reaction with hydrogen sulfide gives a high yield of thioxanthene II (64–65%). The behavior of II in dehydrogenation over Pd/C, and of II and IV to oxidation are investigated. IR spectrum data are given for II and its sulfone.     

Preparation and analytical properties of a chelating resin containing bicine groups

A polystyrene divinyl benzene based resin containing bicine groups has been prepared and its analytical properties investigated. The pH dependence of sorption of metal on the resin has been determined for Cu(II), Fe(II), Ni(II), Co(II), Zn(II), Hg(II) and Pb(II). The important characteristics of the resin are fast equilibrium, high selectivity and small volume change between its hydrogen and metal forms. These enable it to be applied to the rapid concentration of trace amounts of these metal ions. It shows promise for the separation of lead from other metal ions.     

Determination of Cadmium(ii), Copper(ii), Mercury(ii), and Lead(ii) in Water Using Stochastic Sensors Based on Graphite and Diamond Paste Modified with 1H-Pyrrole-1-Hexanoic Acid

Graphite/diamond pastes modified with 1H-pyrrole-1-hexanoic acid were used for the design of stochastic sensors. The proposed stochastic sensors were used to determine four heavy metals, copper(II), cadmium(II), mercury(II), and lead(II), in water samples. The sensitivities of the stochastic sensors were high for all four metal ions, and their limits of determination were sufficiently low to enable detection at very minute concentrations; in some cases, unreachable using standard methods of analysis. The recoveries of copper(II), cadmium(II), mercury(II), and lead(II) in water samples were higher than 93.00%, with relative standard deviation values lower than 1.00%. The sensors were used to simultaneously determine copper(II), cadmium(II), mercury(II), and lead(II) in water samples. The obtained results were in agreement with those obtained using standard analytical methods.