Spectrophotometric microdetermination of copper(II), silver(I), and gold(III) using azastyrene Schiff bases

A new method for the spectrophotometric microdetermination of Cu(II), Ag(I), and Au(III) using β-2-hydroxybenzyl-5-bromo- (I_a), 5-chloro- (I_b), and 3-methoxy-2-hydroxyazastyrene (I_c) is given. The optimum conditions favoring the formation of the colored complexes are extensively studied. The molecular structure was found to be (1:1) and (1:2) (M:L). Beer's law is obeyed up to 5.00, 8.64, and 11.82 ppm for Cu(II), Ag(I), and Au(III), respectively, while the optimum concentration ranges using the Ringbom method are 0.6–5.00, 1.00–8.60, and 2.00–11.80 ppm for the same metal ions, respectively.     

Fast recovery of Au (III) and Ag(I) via amine-modified zeolitic imidazolate framework-8

In this paper, zeolitic imidazolate framework-8 modified by the ethanediamine (NH₂-ZIF-8) was employed for adsorbing Au (III) and Ag(I) from aqueous solutions. The adsorption capacities of NH₂-ZIF-8 towards Au (III) and Ag(I) were found to be significantly affected by the pH values of the solution. The adsorption kinetics studies show that NH₂-ZIF-8 presents a fast adsorption property towards metals, attaining 93% of adsorption equilibrium uptake for Au (III) within the first 30 min. This phenomenon can be ascribed to the coordination interaction between the amino group and Au (III). The thermodynamic data suggest that the adsorption of NH₂-ZIF-8 towards Au (III) is endothermic process, while that for Ag(I) is exothermic. The maximum adsorption capacities of NH₂-ZIF-8 toward Au (III) and Ag(I) can be achieved to 357 mg·g⁻¹ and 222.25 mg·g⁻¹, respectively. The metal ions interference results show that Cu (II) and Ni (II) hardly have no interference on Au (III) adsorption in e-waste containing 1500 mg·l⁻¹ Cu (II),100 mg·l⁻¹ Ni (II) and 10 mg·l⁻¹ Au (III); while for Ag(I), Cd (II) and Zn (II) have little interference on Ag(I) adsorption in the hybrid solutions containing Ag(I), Ni (II), Cd (II) and Zn (II) with equal concentration (50 mg·l⁻¹), but Ni (II) interference most. The XPS study shows that partial Au (III) was reduced to Au(I), and that Ag(I) was completely reduced to Ag(0) during the adsorption process. The abundant of active sites of NH₂-ZIF-8 containing C=N, N-H, and Zn-OH groups play a key role in the adsorption of Au (III) and Ag(I). In addition, electrostatic interaction can be responsible for the adsorption of Au (III) by NH₂-ZIF-8. The regeneration experiments results show that the adsorption capacities of NH₂-ZIF-8 towards Au (III) and Ag(I) can maintain after three cycles. This work provides a reliable method to improve the adsorption kinetics for metal ions.     

Complexes of gold(I), silver(I), and copper(I) with pentaaryl[60]fullerides

Gold(I), silver(I), and copper(I) phosphine complexes of 6,9,12,15,18-pentaaryl[60]fullerides 1a and 1b, namely, [(4-MeC(6)H(4))(5)C(60)]Au(PPh(3)) (2a), [(4-t-BuC(6)H(4))(5)C(60)]Au(PPh(3)) (2b), [(4-MeC(6)H(4))(5)C(60)]Ag(PCy(3)) (3a), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PPh(3)) (3b), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PCy(3)) (3c), [(4-MeC(6)H(4))(5)C(60)]Cu(PPh(3)) (4a), and [(4-t-BuC(6)H(4))(5)C(60)]Cu(PPh(3)) (4b), have been synthesized and characterized spectroscopically. All complexes except for 3c were also characterized by single-crystal X-ray diffraction. Several coordination modes between the cyclopentadienyl ring embedded in the fullerene and the metal centers are observed, ranging from η(1) with a slight distortion toward η(3) in the case of gold(I), to η(2)/η(3) for silver(I), and η(5) for copper(I). Silver complexes 3a and 3b are rare examples of crystallographically characterized Ag(I) cyclopentadienyls whose preparation was possible thanks to the steric shielding provided by fullerides 1a and 1b, which stabilizes these complexes. Silver complexes 3a and 3b both display unexpected coordination of the cyclopentadienyl portion of the fulleride anion with Ag(I). DFT calculations on the model systems (H(5)C(60))M(PH(3)) and CpMPH(3) (M = Au, Ag, or Cu) were carried out to probe the geometries and electronic structures of these metal complexes.     

Selenolate gold complexes with aurophilic Au(I)-Au(I) and Au(I)-Au(III) interactions

The gold(I) selenolate compound [Au(2)(SePh)(2)(mu-dppf)] (dppf = 1,1'-bis(diphenylphosphino)ferrocene) has been prepared by reaction of [Au(2)Cl(2)(mu-dppf)] with PhSeSiMe(3) in a molar ratio 1:2. This complex reacts with gold(I) or gold(III) derivatives to give polynuclear gold(I)-gold(I) or gold(I)-gold(III) complexes of the type [Au(4)(mu-SePh)(2)(PPh(3))(2)(mu-dppf)](OTf)(2), [Au(3)(C(6)F(5))(3)(mu-SePh)(2)(mu-dppf)], or [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)], with bridging selenolate ligands. The reaction of [Au(2)(SePh)(2)(mu-dppf)] with 1 equiv of AgOTf leads to the formation of the insoluble Ag(SePh) and the compound [Au(2)(mu-SePh)(mu-dppf)]OTf. The complexes [Au(4)(C(6)F(5))(6)(mu-SePh)(2)(mu-dppf)] and [Au(2)(mu-SePh)(mu-dppf)]OTf (two different solvates) have been characterized by X-ray diffraction studies and show the presence of weak gold(I)-gold(III) interactions in the former and intra- and intermolecular gold(I)-gold(I) inter-actions in the later.     

Tris(2,2′-bipyridyl)iron(II)tetraphenylborate as a solid analytical reagent in the spectrophotometric determination of Ag(I), Tl(I), and Hg(II)

Analytical applications of a new solid reagent tris(2,2′-dipyridyl)iron(II) tetraphenylborate are described. The solid reagent selectively reacts with Ag(I), Tl(I), and Hg(II) cations to release the colored tris(2,2′-bipyridyl)iron(II) cation in solution, which is determined spectrophotometrically. The experimental data show that the Ag(I), Tl(I), and Hg(II) cations respond linearly in 5 to 50-ppm range.     

Heterovalent Au(III)-M(I) (M=Cu, Ag, Au) complexes derived from incorporation of [Au(tdt)2]- (tdt = toluene-3,4-dithiolate) with [M2(dppm)2]2+ (dppm = Bis(diphenylphosphino)methane)

Polynuclear heterovalent Au(III)-M(I) (M = Cu, Ag, Au) cluster complexes [Au(III)Cu(I)8(mu-dppm)3(tdt)5]+ (1), [Au(III)3Ag(I)8(mu-dppm)4(tdt)8]+ (2), and [Au(III)Au(I)4(mu-dppm)4(tdt)2]3+ (3) were prepared by reaction of [Au(III)(tdt)2]- (tdt = toluene-3,4-dithiolate) with 2 equiv of [M(I)2(dppm)2]2+ (dppm = bis(diphenylphosphino)methane). Complex 3 originates from incorporation of one [Au(III)(tdt)2]- with two [Au(I)2(dppm)2]2+ components through Au(III)-S-Au(I) linkages. Formation of complexes 1 and 2, however, involves rupture of metal-ligand bonds in the metal components and recombination between the ligands and the metal atoms. The Au(tdt)2 component connects to four M(I) atoms through Au(III)-S-M(I) linkages in syn and anti conformations in complexes 1 (M = Cu) and 3 (M = Au), respectively, but in both syn and anti conformations in complex 2 (M = Ag). The tdt ligand exhibits five types of bonding modes in complexes 1-3, chelating Au(III) or M(I) atoms as well as bridging Au(III)-M(I) or M(I)-M(I) atoms in different orientations. Although complexes 1 and 2 are nonemissive, Au(III)Au(I)(4) complex 3 shows room-temperature luminescence with emission maximum at 555 nm (tau(em) = 3.1 micros) in the solid state and at 570 nm (tau(em) = 1.5 micros) in acetonitrile solution.     

Luminescence Determination of Copper(I), Silver(I), Gold(I), and Platinum(II) Using 2-Mercapto-5-Benzimidazolesulfonic Acid,also Immobilized on a Silica Surface

2-Mercapto-5-benzimidazolesulfonic acid (MBI), also noncovalently bound to a silica surface, is proposed as a reagent for the low-temperature luminescence determination of Cu(I), Ag(I), Au(I), and Pt(II). Luminescence excitation and luminescence spectra of metal complexes with MBI in solutions and on the adsorbent surface represent broad unstructured bands in the regions 250–400 and 450–700 nm, respectively. The developed procedures for the luminescence and sorption–luminescence determination of Cu, Ag, Au, and Pt with limits of detection at a level of 0.001–0.01 μg on 0.1 g of adsorbent are tested in the determination of metals in natural and industrial samples.     

Au(I)...Ag(I) metallophilic interactions between anionic units: theoretical studies on a AuAg4 square pyramidal arrangement

We have studied theoretically the organometallic compound (NBu4)2[Au(3,5-C6F3Cl2)2Ag4(CF3CO2)5], whose dianionic part displays a AuAg4 square pyramidal arrangement based on closed-shell Au(I)...Ag(I) interactions between two monoanionic fragments. DFT/B3LYP, ab initio Hartree-Fock (HF), and second-order M?ller Plesset perturbation theory (MP2) calculations have been carried out for simplified model systems. Model system [AuPh2]-...[Ag4(CO2H)5]- (C1) has been chosen from DFT results as an appropriate model for the study of the interactions. The four Au(I)...Ag(I) interactions and two additional C...Ag(I) interactions are observed when dispersion-type interactions are considered in the level of theory (MP2) displaying a metallophilic attraction between two anionic units. The study of model C2 (similar to C1 but with minimized C...Ag(I) interactions) permits the study of the Au(I)...Ag(I) interactions separately, which confirms the existence of stabilizing Au(I)...Ag(I) interactions around 13 kJ.mol(-1) each.     

Highly efficient near-infrared-emitting lanthanide(III) complexes formed by heterogeneous self-assembly of Ag(I), Ln(III), and thiacalix[4]arene-p-tetrasulfonate in aqueous solution (Ln(III) = Nd(III), Yb(III))

Heterogeneous self-assembly of thiacalix[4]arene-p-tetrasulfonate (TCAS), Ag(I), and Ln(III) (= Nd(III), Yb(III)) in aqueous solutions conveniently afforded ternary complexes emitting Ln(III)-centered luminescence in the near-infrared (NIR) region. A solution-state study revealed that the Ag(I)-Nd(III)-TCAS system gave a complex Ag(I)(4)·Nd(III)·TCAS(2) in a wide pH range of 6-12. In contrast, the Ag(I)-Yb(III)-TCAS system gave Ag(I)(2)·Yb(III)(2)·TCAS(2) at a pH of around 6 and Ag(I)(2)·Yb(III)·TCAS(2) at a pH of approximately 9.5. The structures of the Yb(III) complexes were proposed based on comparison with known Ag(I)-Tb(III)-TCAS complexes that show the same self-assembly behavior. In Ag(I)(2)·Yb(III)(2)·TCAS(2), two TCAS ligands sandwiched a cyclic array of a Ag(I)-Ag(I)-Yb(III)-Yb(III) core. In Ag(I)(2)·Yb(III)·TCAS(2), Yb(III) was accommodated in an O(8) cube consisting of eight phenolate O(-) groups from two TCAS ligands linked by two S-Ag-S linkages. Crystallographic analysis of Ag(I)(4)·Nd(III)·TCAS(2) revealed that the structure was similar to Ag(I)(2)·Yb(III)·TCAS(2) but that it had four instead of two S-Ag-S linkages. The number of water molecules coordinating to Ln(III) (q) estimated on the basis of the luminescent lifetimes was as follows: Ag(I)(4)·Nd(III)·TCAS(2), 0; Ag(I)(2)·Yb(III)(2)·TCAS(2), 2.4; and Ag(I)(2)·Yb(III)·TCAS(2), 0. These findings were compatible with the solution-state structures. The luminescent quantum yield (Φ) for Ag(I)(4)·Nd(III)·TCAS(2) was 4.9 × 10(-4), which is the second largest value ever reported in H(2)O. These findings suggest that the O(8) cube is an ideal environment to circumvent deactivation via O-H oscillation of coordinating water. The Φ values for Ag(I)(2)·Yb(III)(2)·TCAS(2) and Ag(I)(2)·Yb(III)·TCAS(2) were found to be 3.8 × 10(-4) and 3.3 × 10(-3), respectively, reflecting the q value. Overall, these results indicate that the ternary systems have the potential for a noncovalent strategy via self-assembly of the multidentate ligand, Ln(III), and an auxiliary metal ion to obtain a highly efficient NIR-emissive Ln(III) complex that usually relies on elaborate covalent linkage of a chromophore and multidentate ligands to expel coordinating water.     

Studies on the synthesis of 5-(p-aminobenzylidene)-rhodanine and its properties

A new analytical reagent 5-(p-aminobenzylidene)-rhodanine (ABR) was synthesized. The acidic dissociation constant of ABR has been determined. The properties, the acid-base behavior of ABR and the reactions of ABR with metallic ions have been studied. The color reactions of the reagent with Pd(II), Au(III), Ag(I), Ru(III), Hg(II) and Cu(II) are studied in detail. The composition of Pd(II)-ABR, Au(III)-ABR and Ag(I)-ABR complexes were discussed.     

Potentiometric determination of silver(I), palladium(II) and gold(III) in mixtures by use of an iodide-selective electrode

Two procedures are proposed for the potentiometric determination of Ag(I), Pd(II) and Au(III) in binary mixtures, by titration with potassium iodide solution, and use of a commercial iodide electrode as sensor. In the first procedure, two aliquots of the mixture are titrated, at pH 2.0 ± 0.2 and 9.0 ± 0.2, adjusted with dilute sulphuric acid and ammonia solution. At pH 2.0, the titrant reacts with both metals, whereas at pH 9.0, Ag(I) is the only reactant. The second procedure utilizes titration of two aliquots of the mixture in the presence and absence of a selective masking agent. The methods have been applied to the determination of these metals in some jewellery alloys.     

Ability of a Au(III)-N unit to bond two aurophilically interacting gold(I) centers

The monohapto neutral 2-(diphenylphosphino)aniline (PNH(2)) complexes [Au(C(6)F(5))(2)X(PNH(2))] (X = C(6)F(5) (1), Cl (2)) have been obtained from [Au(C(6)F(5))(3)(tht)] or [Au(C(6)F(5))(2)(micro-Cl)](2) and PNH(2), and the cationic [Au(C(6)F(5))(2)(PNH(2))]ClO(4) (3) has been similarly prepared from [Au(C(6)F(5))(2)(OEt(2))(2)]ClO(4) and PNH(2) or from 2 and AgClO(4). The neutral amido complex [Au(C(6)F(5))(2)(PNH)] (4) can be obtained by deprotonation of 3 with PPN(acac) (acac = acetylacetonate) or by treatment of the chloro complex 2 with Tl(acac). It reacts with [Ag(OClO(3))(PPh(3))] or [Au(OClO(3))(PPh(3))] to give the dinuclear species [Au(C(6)F(5))(2)[PNH(MPPh(3))]]ClO(4) (M = Ag (5), Au (6)). The latter can also be obtained by reaction of equimolar amounts of 3 and [Au(acac)(PPh(3))]; when the molar ratio of the same reagents is 1:2, the trinuclear cationic complex [Au(C(6)F(5))(2)[PN(AuPPh(3))(2)]]ClO(4) (7) is obtained. The crystal structures of complexes 2-4 and 7 have been established by X-ray crystallography; the last-mentioned displays an unusual Au(I)-Au(III) interaction.     

New spot tests for thallium(I), bismuth(III), and iodide

Microchimica Acta - New spot tests are described for the selective detection of Tl(I), Bi(III), and I? ions, with limits of detection 4 μg, 5 μg, and 15 μg respectively, and...     

MAMT,a new chromogenic reagent for Ru,Rh, Pd,Pt and Au in TLC,and for their evaluation by ring colorimetry

Summary Micro-analytical separations of some platinum metals [Ru(III), Rh(III), Pd(II), Pt(IV), and Au(III)] in mixed solutions of their salts have been carried out by ascending thin layer chromatography on Silica Gel G. 3-Mercapto-4-amino-5-methyl-1,2,4-triazole (MAMT) has been successfully used for the visualisation of the above ions on TLC plates and also for colorimetric evaluation of the chromatographed species by ring colorimetry.MAMT=3-Mercapto-4-amino-5-methyl-1,2,4-triazole     

Extraction and determination of trace amounts of gold(III), palladium(II), platinum(II) and silver(I) with the aid of a magnetic nanosorbent made from Fe3O4-decorated and silica-coated graphene oxide modified with a polypyrrole-polythiophene copolymer

Microchimica Acta - The authors describe the synthesis of a nanosorbent for fast magnetic solid phase extraction of trace levels of Ag(I), Au(III), Pd(II) and Pt(II). It consists of graphene oxide...     

Solubility, complex formation, and redox reactions in the Tl2O3-HCN/CN(-)-H2O system. Crystal structures of the cyano compounds Tl(CN)3.H2O, Na[Tl(CN)4].3H2O, K[Tl(CN)4], and Tl(I)[Tl(III)(CN)4] and of Tl(I)2C2O4

Thallium(III) oxide can be dissolved in water in the presence of strongly complexing cyanide ions. Tl(III) is leached from its oxide both by aqueous solutions of hydrogen cyanide and by alkali-metal cyanides. The dominating cyano complex of thallium(III) obtained by dissolution of Tl2O3 in HCN is [Tl(CN)3(aq)] as shown by 205Tl NMR. The Tl(CN)3 species has been selectively extracted into diethyl ether from aqueous solution with the ratio CN-/Tl(III) = 3. When aqueous solutions of the MCN (M = Na+, K+) salts are used to dissolve thallium(III) oxide, the equilibrium in liquid phase is fully shifted to the [Tl(CN)4]- complex. The Tl(CN)3 and Tl(CN)4- species have for the first time been synthesized in the solid state as Tl(CN)3.H2O (1), M[Tl(CN)4] (M = Tl (2) and K (3)), and Na[Tl(CN)4].3H2O (4) salts, and their structures have been determined by single-crystal X-ray diffraction. In the crystal structure of 1, the thallium(III) ion has a trigonal bipyramidal coordination with three cyanide ions in the equatorial plane, while an oxygen atom of the water molecule and a nitrogen atom from a cyanide ligand, attached to a neighboring thallium complex, form a linear O-Tl-N fragment. In the three compounds of the tetracyano-thallium(III) complex, 2-4, the [Tl(CN)4]- unit has a distorted tetrahedral geometry. Along with the acidic leaching (enhanced by Tl(III)-CN- complex formation), an effective reductive dissolution of the thallium(III) oxide can also take place in the Tl2O3-HCN-H2O system yielding thallium(I), while hydrogen cyanide is oxidized to cyanogen. The latter is hydrolyzed in aqueous solution giving rise to a number of products including (CONH2)2, NCO-, and NH4+ detected by 14N NMR. The crystalline compounds, Tl(I)[Tl(III)(CN)4], Tl(I)2C2O4, and (CONH2)2, have been obtained as products of the redox reactions in the system.     

Synthesis,characterization, and antimicrobial activities of Cu(I), Ag(I), Au(I), and Co(II) complexes with [CH3N(CH2PPh2)2]

Transition metal complexes of ditertiary aminomethylphosphine ligand, (Ph₂PCH₂)NCH₃ [N,N‐bis(diphenylphospinomethyl)aminomethane], dppam, with metal ions which are Ag(I), Au(I), Cu(I), and Co(II) have been synthesized under nitrogen atmosphere by the Schlenk method. [Ag(dppam)₂]NO₃ ( 1 ), [Au(dppam)₂]Cl ( 2 ), and [Cu(dppam)₂]Cl ( 3 ) complexes have been isolated as colorless solids, whereas [CoCl₂(dppam)] ( 4 ) complex as a blue solid. All complexes have been characterized by atomic absorption, FT‐IR, NMR (¹H, ¹³C, ³¹P) spectroscopic, thermogravimetric/differantial thermal analysis (TG/DTA), and elemental analysis techniques. Antimicrobial activity of 1 , 2 , 3 , and 4 were studied in vitro on 13 bacteria and 4 yeasts. The cobalt(II) phosphine complex has shown the best antimicrobial activity in comparison with the other metal complexes. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:484–491, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20145     

Microdetermination of gold(III), silver(I) and ruthenium (III) by ring colorimetry after separation by thin-layer chromatography (TLC)

Summary Clean and speedy analytical separation ofg quantities of Au(III), Ru(III) and Ag(I) from their mixed solution is accomplished by ascending thin-layer chromatography. For the evaluation of these metal ions, the spots are scooped out with the help of a Mottier gadget and the collected material transferred to the paper set on the ring oven. Separate rings were obtained for individual metal ions and the determination is carried out by ring colorimetry, using PTC as a fixing and complexing agent for washing to the ring.

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Zusammenfassung Mikrogrammengen Au(III), Ru(III) und Ag(I) lassen sich voneinander aus Lösungsgemischen sauber und rasch durch aufsteigende Dünnschichtchromatographie trennen. Für die Auswertung der Flecken werden diese abgekratzt, mit Hilfe des vonMottier beschriebenen Sauggerätes gesammelt und auf dem Ringofen auf Papier übertragen. Für die einzelnen Metallionen erhält man getrennte Ringe, die kolorimetrisch vermessen werden, wobei Kaliumthiocarbonat zur Fixierung und Komplexbildung dient.

     

Chloroform extraction of ethyl xanthate complexes from sulphuric acid media

The chloroform extraction of 30 elements (Fe, Co, Ni, Zn, Cd, Ge, Sn, V, As, Sb, Bi, Cu, Ag, Au, Mn, Re, Ga, In, Tl, Se, Te, Cr, Mo, U, Pt, Pd, Rh, Ir, Ru and Ce) from 0.1-8M sulphuric acid in the presence of potassium ethyl xanthate has been studied. Pd(II), Bi, As(III), Sb(III), Se(IV) and Te(IV) are completely extracted and Au(III) is largely extracted over the range of acid concentration investigated. Fe(II), Tl(I), Rh(III) and Cr(VI) are only slightly extracted and Se(VI), Te(VI), Ru(III), Cr(III), Mn(II), Zn, Ce(IV), Ir(IV) and Ge(IV) are not extracted at all. Depending on the acid concentration, the remaining elements are all partly extracted. Results are compared with those obtained in an earlier study of the extraction of xanthate complexes from hydrochloric acid media. The processes involved in the formation of some xanthate complexes and potential analytical separations are discussed.     

Synthesis and Applications of Poly(Acrylphenylamidrazone-Phenyl-Hydrazide-Acylphenylhydrazine) Chelating Fiber for Preconcentration and Separation of Trae In(III), Zr(IV), Tl(I), V(V), Ga(III) and Ti(IV) from Solution Samples

 An ICP-OES method using a new poly (acrylphenylamidrazone-phenylhydrazide-acylphenylhydrazine) chelating fiber to preconcentrate and separate trace In(III), Zr(IV), Tl(I), V(V), Ga(III) and Ti(IV) ions from solution samples has been established. The new chelating fiber was synthesized using polyacrylonitrile fiber as a starting material and the structure of the chelating fiber was determined by FT infrared spectrometry. The acidity, adsorption rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that the relative standard deviations for the determination of 10 ng/ml In, Tl, Ga and 1 ng/ml Zr, V, Ti were lower than 2.5%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 4%. Received November 29, 2000. Revision May 22, 2001.