Preparation of poly(vinylalcohol)/poly(acrylamide‐co‐vinyl imidazole)/γ‐Fe2O3 semi‐IPN nanocomposite and their application for removal of heavy metal ions from water

A series of magnetic semi‐interpenetrating polymer network (semi‐IPN) hydrogels was prepared in one‐stage strategy composed of linear poly(vinyl alcohol) (PVA) chains and magnetic γ‐Fe₂O₃ nanoparticles entrapped within the cross‐linked poly(acrylamide‐co‐vinylimidazole) (poly(AAm‐co‐VI)) network. The influence of PVA, weight ratio of AAm:VI, γ‐Fe₂O₃, and MBA on the swelling properties of the obtained nanocomposite hydrogels was evaluated. The prepared magnetic semi‐IPN hydrogels were fully characterized and used as absorbent for removal of Pb(II) and Cd(II) from water. Factors that influence the metal ion adsorption such as solution pH, contact time, initial metal ion concentration, and temperature were studied in details. The experimental results were reliably described by Langmuir adsorption isotherms. The adsorption capacity of semi‐IPN nanocomposite for Pb(II) and Cd(II) were175.80 and 149.76 mg g^?1, respectively. The kinetic experimental data indicated that the chemical sorption is the rate‐determining step. According to thermodynamic studies, Pb(II) and Cd(II) adsorption on the hydrogels was endothermic and also chemical in nature. The prepared magnetic PVA/poly(AAm‐co‐VI) semi‐IPN hydrogels could be employed as efficient and low‐cost adsorbents of heavy metal ions from water. Copyright © 2016 John Wiley & Sons, Ltd.     

Electrochemical Investigation of Heavy Metal Ion Transfer Across the Water/1,2‐Dichloroethane Interface Assisted by 9‐Ethyl‐3‐Carbazolecarboxaldehyde‐Thiosemicarbazone

The transfer of heavy metal ions across the polarized water/1,2‐dichloroethane (1,2‐DCE) interface assisted by 9‐ethyl‐3‐carbazolecarboxaldehyde‐thiosemicarbazone (ECCAT) in the 1,2‐DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi‐reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two‐step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half‐wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion‐transfer is assisted by the formation of 1:3 metal‐ECCAT complex in 1,2‐DCE. The over‐all association constants of [Pb(ECCAT)₃]²⁺ and [Cd(ECCAT)₃]²⁺ complexes in DCE‐phase have been determined to be log β =14.03 and log β =15.44, respectively.     

Novel salep‐based chelating hydrogel for heavy metal removal from aqueous solutions

A novel optimized chelating hydrogel was synthesized via graft copolymerization of acrylamide and 2‐hydroxyethyl methacrylate (as two‐dentate chelating co‐monomer) onto salep (a multicomponent polysaccharide obtained from dried tubers of certain natural terrestrial orchids) using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Reaction parameters (N,N′‐methylenebisacrylamide and ammonium persulfate amounts as well as acrylamide/2‐hydroxyethyl methacrylate weight ratio) affecting the water absorption of the chelating hydrogel were optimized using a systematic method to achieve a hydrogel with high swelling capacity as possible. Heavy metal ion adsorption capacity of the optimized hydrogel for metal ions [Cu (II), Pb (II), Cd (II), and Cr (III)] were investigated in aqueous media containing different concentrations of these ions (5–50 ppm). The results showed that the hydrogel have great potential for heavy metal removal from aqueous solutions. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy, and surface morphology study of the hydrogel was performed by scanning electron microscope. Copyright © 2016 John Wiley & Sons, Ltd.     

Coordination polymers of CdII and PbII derived from bipyridine–glycoluril: influence of metal‐ion size and counter‐ions

Two new one‐dimensional (1D) coordination polymers (CPs), namely catena‐poly[[[aquacadmium(II)]‐bis(μ‐4b,5,7,7a‐tetrahydro‐4b,7a‐epiminomethanoimino‐6H‐imidazo[4,5‐f][1,10]phenanthroline‐6,13‐dione)] bis(perchlorate) dihydrate], {[Cd(C₁₄H₁₀N₆O₂)₂(H₂O)](ClO₄)₂·2H₂O}_n or {[Cd(BPG)₂(H₂O)](ClO₄)₂·2H₂O}_n, 1 , and catena‐poly[[lead(II)‐bis(μ‐4b,5,7,7a‐tetrahydro‐4b,7a‐epiminomethanoimino‐6H‐imidazo[4,5‐f][1,10]phenanthroline‐6,13‐dione)] bis(perchlorate) dihydrate], {[Pb(C₁₄H₁₀N₆O₂)₂](ClO₄)₂·2H₂O}_n or {[Pb(BPG)₂](ClO₄)₂·2H₂O}_n, 2 , have been synthesized using bipyridine–glycoluril (BPG; systematic name: 4b,5,7,7a‐tetrahydro‐4b,7a‐epiminomethanoimino‐6H‐imidazo[4,5‐f][1,10]phenanthroline‐6,13‐dione), a urea‐fused tecton, in a mixed‐solvent system. The Cd^II ion in 1 is heptacoordinated and the Pb^II ion in 2 is hexacoordinated, with the Cd^II ion adopting a pentagonal bipyramidal geometry and the Pb^II ion adopting a distorted octahedral geometry. Both CPs form infinite linear chain structures which are hydrogen bonded to each other leading to the formation of three‐dimensional supramolecular network structures. Topological analysis of CPs 1 and 2 reveals that the structures exhibit 1D chain‐like arrangements in an AB–AB sequence and shows platonic uniform 2‐connected uninodal topologies. Furthermore, a comparative analysis of a series of structures based on the BPG ligand indicates that the size of the metal ion and the types of counter‐ions used have a great influence on the resulting frameworks and properties.     

Metalloporphyrins‐Al3+ porous coordination polymers: Preparations,Characterizations and Catalytic Properties

In this work, metalloporphyrins‐based MOGs were synthesized as precursor to prepare porous coordination polymers (PCPs). Firstly, the carboxyl metalloporphyrins MCPp (M = Zn (II), Co (II), Cu (II), Mn (III)OAc; CPp = 5,10,15,20‐tetra(4‐(3‐carboxy)phenoxy)phenylporphyrin) were synthesized as gelator. Then, the metalloporphyrin‐based MOGs were prepared with MCPp and Al(NO₃)₃·9H₂O by sol–gel method. Moreover, the residual reactants and solvent molecules in MOGs were removed by Soxhlet extraction and supercritical CO₂ extraction to get the finial porous coordination polymers. This methodology effectually avoids the collapse of frame construction. Compared with the reference material prepared by the oven‐dry method, these PCPs exhibit much higher BET surface ranging from 398 to 439 m² g^?1. The PCPs were carefully characterized by FT‐IR, UV–vis, SEM, TEM and PXRD, and exhibit excellent catalytic activities and stabilities for the oxidation of ethylbenzene.     

Synthesis of a rare‐metal adsorbing polymer by three‐component polyaddition of diamines,carbon disulfide,and diacrylates in an aqueous/organic biphasic medium

Three‐component polyaddition of diamines, carbon disulfide (CS₂), and diacrylates in an aqueous/organic biphasic medium produced a polymer capable of adsorbing rare metals. By using a 1:1 mixture of toluene and H₂O, the polyaddition reaction of 1,3‐di‐4‐piperidylpropane (1), CS₂, and 1,6‐hexanediol diacrylate (2) proceeded efficiently in the presence of Et₃N to produce a poly(dithiourethane‐amine) with a high proportion of dithiourethane units almost quantitatively. Quantitative formation of 1‐CS₂ adducts in the aqueous phase was followed by efficient reaction with diacrylate at the biphasic interface. The resulting poly(dithiourethane‐amine) adsorbed Pd(II) and Pt(IV) efficiently under acidic conditions due to the high affinity of thiocarbonyl sulfur atoms for soft metal ions. The polymers showed highly selective adsorption of Pd(II) from a mixture of metal ions [Pd(II), Cr(III), Cu(II), Fe(III), Mn(II), Pb(II), and Zn(II)], indicating their potential utilization for selective recovery of rare‐metals. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of transition‐metal‐ion‐selective poly(N‐isopropylacrylamide) hydrogels by the incorporation of an Aza crown ether

A functionalized cyclam was synthesized by the attachment of a polymerizable acryloyl group to one of the four nitrogens on the cyclam molecule. The polymerization of the functionalized cyclam was performed with N‐isopropylacrylamide and N,N′‐methylene bisacrylamide, and the gels obtained were studied in the presence of different transition‐metal‐ion solutions. There was a drastic difference in the phase‐transition temperature (T_c) of the poly(N‐isopropylacrylamide) (PNIPAAm)/cyclam gel in comparison with the pure PNIPAAm gel. For the described system, a T_c shift of 15 °C was obtained. The presence of functionalized cyclam increased the hydrophilicity and T_c of the aforementioned polymer gels in deionized water (at pH 6) because of the presence of protonated amino moieties. The PNIPAAm/cyclam gels showed a dependence of the swelling behavior on pH. T_c of the pure PNIPAAm gel was weakly influenced by the presence of any transition‐metal ions, such as Cu²⁺, Ni²⁺, Zn²⁺, and Mn²⁺. The addition of Cu²⁺ or Ni²⁺ to the PNIPAAm/cyclam gel reduced T_c of the polymer gel, and a shift of approximately 12 °C was observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1594–1602, 2003     

Polyoxometalate encapsulated in metal‐organic gel as an efficient catalyst for visible‐light‐driven dye degradation applications

Contamination of industrial sewage by organic dye pollutants is one of the most common challenges to the daily life. Decontamination can be achieved by adsorption and photodegradation of the pollutants. Herein, an effective visible light‐driven photocatalyst of polyoxometalate encapsulated in metal–organic gel was presented. The resulting composite was named PMA@ MOG‐Cr [PMA= H₃PMo₁₂O₄₀, MOG= metal‐organic gel]. Photodegradation of dye pollutants with PMA@ MOG‐Cr were tested. The introduction of Phosphomolybdic Acid significantly enhanced the light‐absorption properties of MOG‐Cr. The PMA@MOG‐Cr showed an excellent photodegradation efficiency of MB, RhB and MO as high as 99% and 97% in 60 min and 91% in 120 min of visible‐light irradiation with only 10 mg photocatalyst, which was the highest among the tested samples MOG‐Cr, PMA@ MOG‐Cr and Degussa P‐25. The mechanism of the photodegradation of dye pollutants with H₂O₂ over PMA@MOG‐Cr under the visible light was further illustrated. The introduction of PMA promotes effective separation of electron–hole pair by trapping and transferring photogenerated electron. Thus, the two components act in synergy to result in much improved adsorption of certain common organic dyes as well as enhanced oxidative degradation. This work provides a new approach to design MOG encapsulated Polyoxometalate for visible light‐induced photodegradation of organic contaminants for the environmental remediation.     

Enhanced swelling and adsorption properties of AAm‐AMPSNa/clay hydrogel nanocomposites for heavy metal ion removal

Novel type hydrogel‐clay nanocomposites based on the acrylamide (AAm)‐ 2‐acrylamido‐ 2‐methylpropane sulfonic acid (AMPS) sodium salt and clay were synthesized via in situ copolymerization in aqueous solution. Samples were characterized by determining total basic group (TGB) content and swelling degree, XRD analysis, and FTIR spectroscopy. Effects of monomer ratio and clay amount on the swelling properties of the samples were investigated. It was found that the hydrogel/clay nanocomposites exhibited improved swelling capacity compared with the hydrogels. Samples were used to remove heavy metal ions (Cu (II), Cd (II), and Pb (II)) from aqueous solution in competitive and non‐competitive conditions for the first time. The effects of time and pH of the initial metal ion solution on the adsorption capacity were investigated and selectivity properties of the samples were evaluated. It was found that incorporation of a low amount of clay (10% (wt)) into the polymer structure increased the heavy metal ion adsorption capacity of the sample. It was concluded that the AAm‐AMPS/clay nanocomposites could be used as novel type, fast‐responsive, and high capacity sorbent materials in heavy metal removing processes. Copyright © 2007 John Wiley & Sons, Ltd.     

A three‐dimensional metal–organic polymer: poly[bis(μ2‐pyrimidine‐2‐thiolato‐κ4N1,S:S,N3)lead(II)]

The title compound, [Pb(C₄H₃N₂S)₂]_n, was prepared by the reaction of [Pb(OAc)₂]·3H₂O (OAc is acetate) with pyrimidine‐2‐thione in the presence of triethylamine in methanol. In the crystal structure, the Pb^II atom has an N₄S₄ coordination environment with four ligands coordinated by N‐ and S‐donor atoms. This compound shows that the pyrimidine‐2‐thiolate anion can lead to a three‐dimensional network when the coordination number of the metal ion can be higher than 6, as is the case with the Pb^II ion. This compound presents only covalent bonds, showing that despite the possibility of the hemidirected geometries of Pb^II, the eight‐coordinated ion does not allow the formation of an isolated molecular structure with pyrimidine‐2‐thiolate as the ligand.     

Thiosemicarbazone Scaffold as a Multidentate Ligand for Transition‐Metal Ions: Synthesis,Characterization, In Vitro Antimicrobial,Anthelmintic, DNA Cleavage,and Cytotoxic Studies

New series of Schiff bases derived from o‐substituted thiosemicarbazides and 8‐formyl‐7‐hydroxy‐4‐methylcoumarin have been synthesized and their coordination tendency toward Co(II), Ni(II), and Cu(II) metal ions is studied. Analytical, spectral (IR, UV‐Vis, ESR, and FAB‐mass), magnetic, and thermal studies suggests octahedral geometry of the type ML₂ for all the Co(II), Ni(II), and Cu(II) complexes. The complexes are soluble in DMF/DMSO and are non‐electrolytes. The Schiff bases and their metal complexes have been screened for antibacterial (Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Pseudomonas aeruginosa) and antifungal activities (Aspergillus flavus, Aspergillus niger, and Cladosporium) by minimum inhibitory concentration method. DNA cleavage is studied by agarose gel electrophoresis method. Metal (II) complexes show good anthelmintic activity when compared to Schiff bases.     

Synthesis,Crystal Structure and Photoluminescence Property of Zinc(II), Cadmium(II), and Lead(II) Complexes with Bidentate Ligand: 1‐(1‐Imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB)

Assembly of bidentate ligand 1‐(1‐imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB) with varied metal salts of Zn^II, Cd^II and Pb^II provide three new complexes, [Zn(IIMB)₂](ClO₄)₂·2H₂O ( 1 ), [Cd(IIMB)₂(SCN)₂] ( 2 ) and [Pb(IIMB)₂(SCN)](SCN) ( 3 ). Single crystal X‐ray diffraction studies revealed that complexes 1 and 2 display a similar one‐dimensional double stranded chain structure, while complex 3 is a slight distorted rhombohedral grid network with (4,4) topology. The results indicate that the coordination geometry of the metal ion and the counter anion have great impact on the structure of the complexes. In addition, the photoluminescence properties of ligand IIMB and complexes 1 – 3 were studied in the solid state at room temperature.     

Metal‐Substituted Zeolitic Imidazolate Framework ZIF‐108: Gas‐Sorption and Membrane‐Separation Properties

A series of dual‐metal zeolitic imidazolate framework (ZIF) crystals with SOD and RHO topologies was synthesised by metal substitution from ZIF‐108 (Zn(2‐nitroimidazolate)₂, SOD topology) as the parent material. This was based on the concept that metal substitution of ZIF‐108 requires a much lower activation energy than homogenous nucleation owing to the metastability of ZIF‐108. In‐depth investigations of the formation processes of the daughter ZIFs indicated that the transformation of ZIF‐108 is a dissolution/heterogeneous nucleation process. Typical isostructural Co²⁺ substitution mainly occurs at the outer surface of ZIF‐108 and results in a core–shell structure. On the contrary, the Cu²⁺‐substituted ZIF has a RHO topology with a homogeneous distribution of Cu²⁺ ions in the structure. Substitution with Ni²⁺ resulted in a remarkable enhancement in adsorption selectivity toward CO₂ over N₂ by a factor of up to 227. With Co²⁺‐substituted nanoparticles as inorganic filler, a mixed matrix membrane based on polysulfone displayed greatly improved performance in the separation of H₂/CH₄, CO₂/N₂ and CO₂/CH₄.     

Reversible Self‐Assembly of Carboxylated Peptide‐Functionalized Gold Nanoparticles Driven by Metal‐Ion Coordination

Carboxylated peptide‐functionalized gold nanoparticles (peptide‐GNPs) self‐assemble into two‐ and three‐dimensional nanostructures in the presence of various heavy metal ions (i.e. Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺) in aqueous solution. The assembly process is monitored by following the changes in the surface plasmon resonance (SPR) band of gold nanoparticles in a UV/Vis spectrophotometer, which shows the development of a new SPR band in the higher‐wavelength region. The extent of assembly is dependent on the amount of metal ions present in the medium and also the time of assembly. TEM analysis clearly shows formation of two‐ and three‐dimensional nanostructures. The assembly process is completely reversible by addition of alkaline ethylenediaminetetraacetic acid (EDTA) solution. The driving force for the assembly of peptide‐GNPs is mainly metal ion/carboxylate coordination. The color and spectral changes due to this assembly can be used for detection of these heavy‐metal ions in solution.     

Microwave‐Assisted Synthesis of HKUST‐1 and Functionalized HKUST‐1‐@H3PW12O40: Selective Adsorption of Heavy Metal Ions in Water Analyzed with Synchrotron Radiation

A simple, rapid and efficient synthesis of the metal‐organic framework (MOF) HKUST‐1 [Cu₃(1,3,5‐benzene‐tri‐carboxilic‐acid)₂] by microwave irradiation is described, which afforded a homogeneous and highly selective material. The unusually short time to complete the synthesis by microwave irradiation is mainly attributable to rapid nucleation rather than to crystal growth rate. Using this method, HKUST‐1‐MW (MW=microwave) could be prepared within 20 min, whereas by hydrothermal synthesis, involving conventional heating, the preparation time is 8 h. Work efficiency was improved by the good performance of the obtained HKUST‐1‐MW which exhibited good selective adsorption of heavy metal ions, as well as a remarkably high adsorption affinity and adsorption capacity, but no adsorption of Hg²⁺ under the same experimental conditions. Of particular importance is the preservation of the structure after metal‐ion adsorption, which remained virtually intact, with only a few changes in X‐ray diffraction intensity and a moderate decline in surface area. Synthesis of the polyoxometalate‐containing HKUST‐1‐MW@H₃PW₁₂O₄₀ afforded a MOF with enhanced stability in water, due to the introduced Keggin‐type phosphotungstate, which systematically occluded in the cavities constituting the walls between the mesopores. Different Cu/W ratios were investigated according to the extrusion rate of cooper ions concentration, without significant structural changes after adsorption. The MOFs obtained feature particle sizes between 10–20 μm and their structures were determined using synchrotron‐based X‐ray diffraction. The results of this study can be considered important for potentially wider future applications of MOFs, especially to attend environmental issues.     

Membrane Transport of Pb(II) with a Cooperative Carrier Composed of Dibenzyldiaza‐18‐Crown‐6 and Palmitic Acid

A chloroform membrane system containing a given mixture of dibenzyldiaza‐18‐crown‐6 and palmetic acid was applied for transport of Pb²⁺ ions. The transport was capable of moving metal ions “uphill”. Thus, it was possible to follow the transfer of Pb(II) from the aqueous source phase to the organic layer and from the organic layer to the receiving phase. The effects of thiosulfate concentration in the receiving phase, palmetic acid and dibenzyldiaza‐18‐crown‐6 concentration in the organic phase on the efficiency of the transport system were examined. By using S₂O₃^2? ion as metal ion acceptor in the receiving phase, the amount of lead ion transport across the liquid membrane after 150 minutes is 96 ± 1.5%. The selectivity and efficiency of lead transport from aqueous solution containing Cu²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺, Ca²⁺ were investigated. In the presence of thiosulfate as a suitable masking agent in the source phase, the interfering effects of Ag⁺ and Cu²⁺ were diminished drastically.     

Properties of Poly(sodium 4‐styrenesulfonate)‐Ionic Liquid Composite Film and Its Application in the Determination of Trace Metals Combined with Bismuth Film Electrode

A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1‐butyl‐3‐methyl‐imidazolium hexafluorophosphate (BMIMPF₆) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4‐styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)₆^4?/Fe(CN)₆^3? can be effectively improved at the PSS‐BMIMPF₆ modified GC. The bismuth modified PSS‐BMIMPF₆ composite film electrodes (GC/PSS‐BMIMPF₆/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS‐BMIMPF₆/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50 μg L^?1. And the detection limits were 0.07 μg L^?1 for Cd(II) and 0.09 μg L^?1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120 s, respectively. Finally, the GC/PSS‐BMIMPF₆/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy.     

Metal‐Ion‐Mediated Tuning of Duplex DNA Binding by Bis(2‐(2‐pyridyl)‐1H‐benzimidazole)

Studies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐(n‐pyridyl)‐1H‐benzimidazole)s (n=2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺. Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co²⁺, Ni²⁺, and Cu²⁺ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.     

The Other Face of Bunsen's Cacodyl Disulfide,Me2As(S)‐S‐AsMe2: The Lewis‐Base Behaviour Towards Heavy Metal Cations

The reaction of Bunsen's cacodyl disulfide, Me₂As(S)‐S‐AsMe₂, with heavy metal cations in methanol produces insoluble salts (complexes) of dimethyldithioarsinic acid, Me₂AsS₂H, and dimethyl arsenium ion, Me₂As:⁺. This arsenium ion prefers to react with Me₂As(S)‐S‐AsMe₂, when in excess, compared to AcO^? or MeOH/H₂O and it is also reactive towards sulfur (S_x, x = 1‐8) producing the stabilized dimethylarsino sulfenium cation, . The complexes (Me₂AsS₂)_xM (x = 1 or 2) are unstable in the presence of their own heavy metal cations decomposing to colored solids. In an attempt to prepare salts of Me₂AsSH, the reactions of (Me₂AsS₂)_xM with triphenylphosphine and trimethyl phosphite gave the metal sulfide and Me₂As‐S‐AsMe₂ instead.     

Synthesis,characterization, metal sorption,and biological activities of organosoluble and thermally stable azoxanthone‐based polyester

The aim of this work was to develop functionalized polyxanthones, poly(azoxanthone‐ester)s (PAXEs), with biological activities and heavy metal sorption abilities. For this purpose, at first, new xanthone‐based diol moiety was synthesized and then used for polymerization with commercial dicarboxylic acids via polycondensation reaction by Vilsmeier adducts. The monomer and all polymers were characterized by Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) spectroscopies, and the physical properties of these PAXEs including solution viscosity, solubility properties, thermal stability, and thermal behavior were studied. The prepared polyesters showed excellent thermal stability and good solubility in polar aprotic solvents. In addition, evaluation of antioxidant activity of the PAXEs by 2,2‐diphenyl‐1‐picrylhydrazyl assay revealed that synthesized polymers have higher antioxidant activity than xanthone nucleus. Also, evaluation of the antibacterial activities of the diol monomer and polymer showed good antibacterial activity against some bacterial strains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa). The results showed that these PAXEs can be used in pharmaceutical and food industry (food packaging). Furthermore, these functionalized polyesters were utilized for extraction of environmentally harmful metal cations such as Cr (VI), Co (II), Ni (II), Cu (II), Pb (II), and Cd (II) from aqueous solutions. Copyright © 2015 John Wiley & Sons, Ltd.