Synthesis,characterization, and application of a new chelating resin functionalized with dithiooxamide

Chloromethylated polystyrene‐divinylbenzene has been functionalized with dithiooxamide. The resulting chelating resin (DTOA) has been characterized by elemental analyses, infrared spectroscopy, thermogravimetric analysis, and metal ion sorption capacities. It has been used for the preconcentration and separation of Cu(II), Zn(II), Cd(II), and Pb(II) prior to their determination by FAAS. Parameters such as the amount of the resin, effect of pH, equilibration rate, sorption and desorption of metal ions, and effect of diverse ions have been studied. The maximum sorption capacities found are 0.97, 0.12, 0.08, and 0.12 mmol g^?1 for Cu(II), Zn(II), Cd(II), and Pb(II) at pH 6.0, 5.5, 1.0, and 5.5, respectively. The preconcentration factors are 100, 100, 50, and 50 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. Recoveries of the metal ions were 96 ± 5, 97 ± 6, 96 ± 5, and 96 ± 5 at 95% confidence level, whereas the limits of detection are 2.0, 1.3, 2.5, and 25.0 μg L^?1 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The calibration curves were linear up to 12 μg mL^?1 (R² = 1.000), 2 μg mL^?1 (R² = 0.998), 2 μg ml^?1 (R² = 1.000), and 5 μg mL^?1 (R² = 0.979) for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The reliability of the method has been tested by analyzing certified samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2281–2285, 2007     

Characterization of thiourea-formaldehyde chelating resin by sorption of chromium(III) in water

With a simple model for a surfactant consisting of a hydrophilic head group and hydrophobic tail groups connected by harmonic springs, the structural change of the association structures of the surfactant in an aqueous solution was studied by using the dissipative particle dynamics (DPD) simulation. The effect of the interaction parameter of DPD particles on the structural change of the association structures was also studied. Simulations show that the proper relative values of these interaction parameters could yield desirable changes for the association structure depending on the concentration of the surfactant. That is, a spherical structure forms at ϕ=0.15, structural change from a spherical to cylindrical one occurs at ϕ=0.26, and a hexagonal structure appears at ϕ=0.30, where ϕ is the volume fraction of surfactant SDS (sodium dodecyl sulfate), and they are in good agreement with observation.     

Palladium and platinum sorption on a thiocarbamoyl‐derivative of chitosan

Novel proton exchange membranes are solvent‐cast from N,N‐dimethylacetamide (DMAc) solutions of the crosslinked poly(arylene ether ketone) copolymer with pendant carboxylic acid group (C‐SPAEK) via poly(ethylene glycol) (PEG) with different amounts. These membranes are formed as a result of physical and chemical crosslinking. In this study, ¹H‐NMR and FTIR have been used to confirm the chemical structures of the copolymers. Mechanical and thermal properties, swelling and proton conductivity are affected by the crosslinker (PEG) content in the copolymers. Compared to the noncrosslinked C‐SPAEK membrane, the crosslinked membranes become more flexible and greatly reduced water uptake and swelling ratio with only slight sacrifice in proton conductivities. And the crosslinked membranes keep higher proton conductivities without a sharply decrease at higher temperature. These results show that the crosslinked membranes have potential applications as proton exchange membranes for fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of magnetic chelating resin based on chitosan for adsorption of Cu(II), Co(II), and Ni(II) ions

Cross-linked magnetic chitosan–diacetylmonoxime Schiff’s base resin (CSMO) was prepared for adsorption of metal ions. CSMO obtained was investigated by means of scanning electron microscope (SEM), FTIR, ¹H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSMO resin toward Cu²⁺, Co²⁺ and Ni²⁺ ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetics was evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 95 ± 4, 60 ± 1.5, and 47 ± 1.5 mg/g for Cu²⁺, Co²⁺ and Ni²⁺ ions, respectively. Cross-linked magnetic CSMO displayed higher adsorption capacity for Cu²⁺ in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSMO were regenerated with an efficiency of greater than 84% using 0.01–0.1 M ethylendiamine tetraacetic acid (EDTA).     

Adsorptive Recovery of Palladium(II) and Platinum(IV) on the Chemically Modified-Microalgal Residue

A biomass waste of microalgae was chemically modified by immobilizing the functional group of polyethyleneimine to prepare a new type of adsorbent. The adsorption test revealed that this adsorbent exhibited remarkably high selectivity for Pd(II) and Pt(IV) over base metal ions in HCl solution. From the adsorption isotherm, its maximum adsorption capacity for Pd(II) and Pt(IV) was evaluated as 2.0 and 0.8 mmol/g, respectively. This adsorbent also exhibited high affinity and selectivity for Pd(II) and Pt(IV) even in the presence of high concentrations of base metals in actual leach liquor.     

Palladium(II) complexes with polyphosphazene

An allylphenoxy-substituted polyphosphazene has been modified via inorganic chemical concepts. The transition metal salt is bis(acetonitrile)dichloropalladium(II). The coordination complexes have been characterized using acid-base solution chemistry, sol-gel phase transitions, thermomechanical property measurements and infrared spectroscopy. Solid complexes of polyphosphazene and PdCl₂ cannot be dissolved in the original solvent (i.e., tetrahydrofuran) used during sample preparation. These polymeric palladium complexes also cannot be disrupted by a stronger base, like triphenylphosphine. There is a monotonic increase in the glass transition temperature at higher concentrations of palladium chloride. T_g of the pure polymer increases by 21°C in the presence of 10 mol% palladium chloride. The increase in high-strain mechanical properties cannot be explained solely by a “filler effect.” At higher PdCl₂ concentrations, there is a direct correlation between the enhancement in T_g, higher mechanical fracture stress, and increased infrared absorbance @ 1092 cm^?1 because of the formation of a palladium-π-complex with allylic substituents in the phenoxy sidegroup. Palladium chloride relinquishes its acetonitrile ligands after dissolution in THF, and the vacant sites in the first-shell coordination sphere of the transition metal are occupied by these allylic substituents in the sidegroup. This produces interchain coordination crosslinks, which modify the thermomechanical properties of polyphosphazene/ PdCl₂ complexes.     

Chlorinative Cyclization of 1,6‐Enynes by Enantioselective Palladium(II)/Palladium(IV) Catalysis

A novel asymmetric catalysis via a palladium(II)/palladium(IV) cycle has been developed by utilizing a chiral spiro bis(isoxazoline) ligand (SPRIX). Intramolecular chlorinative cyclization of 1,6‐enynes catalyzed by a palladium‐SPRIX complex proceeded enantioselectively to afford α‐methylene‐γ‐lactone derivatives.     

Separation of Palladium(II) and Platinum(IV) by Bulk Liquid Membranes during Electrodialysis

Abstract

The process of PdCl₄ ^2? and PtCl₆ ^2? separation extracting from binary hydrochloric mixtures as well as palladium(II) extraction from individual solutions by bulk liquid membranes containing diphenylthiourea and di‐o‐tolylthiourea in 1,2‐dichloroethane is studied at galvanostatic electrodialysis. The effects of the current density, the composition of the liquid membrane and of aqueous solutions on the rate of the metal transport are determined. It is shown that an effective separation of Pt(IV) from Pd(II) is achieved in the presence of an excess of the carrier. Maximum separation factor β_Pt/Pd of 380 is obtained in 1 hour of electrodialysis under optimal conditions. The transport of platinum(IV) is supposed to occur in the form of ionic associates (PdL₄Cl)₂PtCl₆. Platinum(IV) concentration and composition of the strip solution do not exert a considerable influence on the separation factor.     

单宁基酚胺型螯合树脂的制备及对Cr(VI)的吸附

杨梅单宁先与氯化亚砜反应制得氯代单宁,再与聚乙烯亚胺交联合成单宁基酚胺型螯合树脂。通过FTIR、SEM、EDS和XPS对单宁基酚胺型螯合树脂的结构进行表征,并考察了螯合树脂对Cr(VI)的吸附性能。在单宁的分子结构侧链引入氨基,能有效改善单宁基螯合树脂对Cr(VI)的吸附性能,螯合树脂对Cr(VI)的吸附主要为还原吸附,铬主要以Cr(III)的形式吸附到树脂上;在温度为318 K、pH为2.0、Cr(VI)初始质量浓度为500 mg/L时,单宁基酚胺型螯合树脂对Cr(VI)的最大吸附量达到364.46 mg/g;当Cr(VI)初始质量浓度低于20 mg/L时,树脂对铬的吸附率达到95%以上;单宁基酚胺型螯合树脂对Cr(VI)的吸附过程符合Langmuir等温吸附模型和准二级吸附动力学方程。该树脂在含铬废水处理方面具有潜在的应用前景。     

Coordination polymers of Zn(II) and N,N'-bis (carboxymethyl) dithiooxamide

Summary Coordination polymers were synthesized using N,N'-Bis (carboxymethyl) dithiooxamide (NN' CMDTO) and Zinc(II) salts. The complexes were characterized by elemental analyses, IR spectral studies, TGA and viscosity measurements. In the proposed structures the ligand was supposed to be coordinated to metal through sulphur and oxygen.     

Palladium (II) and platinum (II) complexes containing organometallic thiosemicarbazone ligands: Synthesis,characterization, X-ray structures and antitubercular evaluation

A new series of palladium (II) and platinum (II) complexes containing ferrocenyl and cyrhetrenyl thiosemicarbazone ligands were synthesized and characterized. The two-step reaction of the organometallic thiosemicarbazones with i) K₂MCl₄ and ii) PPh₃ and their subsequent recrystallization from CH₂Cl₂/hexane yielded the binuclear complexes [Mˋ{ML_n(η⁵-C₅H₄)C(H)NNC(S)NHR}–(Cl)(PPh₃)] (M′Pd, Pt; ML_nRe(CO)₃, FeCp; RH, CH₃). The structures of the products were inferred from elemental analyses and IR, ¹H and ³¹P NMR spectroscopies. The molecular structures of 2b and 3d were confirmed by single crystal X-ray analysis. All complexes were screened in vitro against Mycobacterium tuberculosis and exhibited only moderate activity in the low micromolar range.     

Selective Pd(II) and Pt(IV) sorption using novel polymers containing azamacrocycle functional groups

The synthesis of a new coordinating polymer containing nitrogen atoms by the copolymerization of a 15-membered triolefinic azamacrocycle, 9, named (E,E,E)-1-[(4-methylphenyl)sulfonyl]-6-[(2-trimethylsilylethyl)sulfonyl]-11-[(4-vinylphenyl)sulfonyl)]-1,6,11-triazacyclopentadeca-3,8,13-triene, with styrene is achieved. The novel polymeric material is characterized by means of elemental analysis, IR, ¹³C-CP MAS, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. We also report the study of palladium and platinum sorption from acidic solutions. A capacity of 0.36 mmol g⁻¹ of polymer for Pd(II) and 0.28 mmol g⁻¹ of polymer for Pt(IV) is determined by the batch-mode. The functionalised polymer presents a high selectivity towards precious metals over base metals such us Cu(II) and Ni(II).     

A chelating resin as a probe for the copper(II) distribution in grape wines

Presented hereafter is the pilot-study of the applicability of resin titration (RT) to mixed solvents in regard to the studies of metal distribution in wines – a beverage that has attracted great attention and that has been extensively studied in the recent years.The RT method of studying the distribution of species is based on the determination of the concentration of metal ions sorbed on the iminodiacetic resin Chelex 100 at different V/w (solution volume/mass of resin). The total metal ion present in the considered solution and the free metal ion are estimated from the titration curves. The method, already applied for water solutions, was tested here in mixed solvent media, at the pH around 3, with known amounts of copper(II) and ligands with different complexing properties. Satisfactory results have been obtained and commented critically.In the application of the RT method, the protonation and the exchange reactions of copper(II) with the considered sorbent were investigated in 12% ethanol, in KCl 0.1 and 1.0 M solutions, according to a well established procedure.Finally, a white grape wine (Riesling) from a winery in Oltrepò Pavese was analyzed with RTs. In the sample obtained before processing the wine, 50% of the total Cu(II) (∼18 μM) was combined with ligands with log α_M equal to 3.3; in the final product, the total Cu(II) was 4 μM, almost totally complexed. According to these findings, the ligands accountable for the copper complexation were not the major components in the wine, as they formed considerably weaker complexes.     

Highly Efficient Alkyne Hydroarylation with Chelating Dicarbene Palladium(II) and Platinum(II) Complexes

1 We report on a novel reaction protocol for the coupling of arenes with alkynes (the Fujiwara reaction), yielding products of formal trans‐hydroarylation of the triple bond. The protocol makes use of a chelating N‐heterocyclic dicarbene palladium(II) complex as catalyst and allows us to perform the reaction in a few hours with only 0.1 mol % catalyst yielding the trans‐hydroarylation product in high yields and with excellent selectivity. We discuss the applicability of this reaction protocol, which appears at present quite general with respect to the alkyne, albeit limited to electron‐rich arenes. We also present the results of catalyst optimisation with respect to the nature of the nitrogen substituents in the carbene units, of the bridging group between the carbene units and of the coordinated anionic ligands. Finally, we also discuss the catalytic performance of a related chelating dicarbene complex of platinum(II).     

Reduction of nitroaromatics with poly(vinylpyridine) complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) anchored to 2- and 4-vinylpyridine polymers of different molecular weights were used for the dihydrogen reduction of various nitroaromatics and benzaldehyde in ethanol at 50°C. Palladium(II) complexes were far more effective than their platinum(II) analogues and the activity decreased with increasing molecular weights of the polymers. The nitroaromatics were selectively and almost completely reduced to the corresponding anilines. During reduction, the orange palladium(II) complexes changed to voluminous green precipitates, which could be used repeatedly and preserved for a long time without any loss of activity. A rate equation of the type: rate = K[Cat] [H₂] has been derived and a reduction mechanism has been proposed on the basis of experimental results and kinetic data.     

Synthesis,characterization and application of a novel nanometer-sized chelating resin for removal of Cu(II), Co(II) and Ni(II) ions from aqueous solutions

A novel nanometer-sized chelating resin (NSCR) was prepared via two steps, First step: copolymerization reaction of N-methacryloxyphtalimide (NMP) with methylenebisacrylamide (MBA) by suspension polymerization method to give ultrafine poly (NMP-co-MBA). Second step: reaction of triethylenetetramine (TETA) with poly (NMP-co-MBA) to give NSCR. The prepared NSCR was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Taller (BET) and thermogravimetric analysis (TGA). This study illustrated the capability of NSCR for extraction of Cu(II), Co(II) and Ni(II) from aquatic solutions. The pH effect, metal ions concentration, temperature and contact time were elaborated in batch experiments. The results showed that high capacities were 1.3, 1.0 and 0.95 mmol/g resin for Cu(II), Ni(II) and Co(II) ions, respectively. The experimental data of adsorption isotherms were convenient for Langmuir isotherm, and the kinetic data illustrated that the removal process was described by pseudo-second order kinetic model. The parameters of Thermo dynamic illustrated that the process of adsorption was endothermic and spontaneous reaction. The prepared NSCR was regenerated and used repetitively for five times with small decrease in adsorption capacity.     

Polymerization of Methyl Methacrylate with Nickel(II) and Palladium(II) Iminopyridyl Mononuclear Bimetallic Complexes

Methyl methacrylate polymerizations with a series of Pd(II) or Ni(II) bimetallic catalysts having general formula [(2-C₅H₄N)–C=N–(Z)–N=C–(2-C₅H₄N)] [MX₂]₂ {Z = (2,6-C₆H₂R₂)₂CH(4-C₆H₅); R = Me, iPr, MX₂ = PdCl₂, NiBr₂} in combination with methylaluminoxane showed that bimetallic Pd(II) catalysts are much more active than their bimetallic Ni(II) nickel and monometallic analogs to give syndiorich poly(methyl methacrylate) with moderate molecular weight.