Mechanisms and efficiency of the simultaneous removal of metals and cyanides by using ferrate(VI): crucial roles of nanocrystalline iron(III) oxyhydroxides and metal carbonates

The reaction of potassium ferrate(VI), K₂FeO₄, with weak‐acid dissociable cyanides—namely, K₂[Zn(CN)₄], K₂[Cd(CN)₄], K₂[Ni(CN)₄], and K₃[Cu(CN)₄]—results in the formation of iron(III) oxyhydroxide nanoparticles that differ in size, crystal structure, and surface area. During cyanide oxidation and the simultaneous reduction of iron(VI), zinc(II), copper(II), and cadmium(II), metallic ions are almost completely removed from solution due to their coprecipitation with the iron(III) oxyhydroxides including 2‐line ferrihydrite, 7‐line ferrihydrite, and/or goethite. Based on the results of XRD, Mössbauer and IR spectroscopies, as well as TEM, X‐ray photoelectron emission spectroscopy, and Brunauer–Emmett–Teller measurements, we suggest three scavenging mechanisms for the removal of metals including their incorporation into the ferrihydrite crystal structure, the formation of a separate phase, and their adsorption onto the precipitate surface. Zn and Cu are preferentially and almost completely incorporated into the crystal structure of the iron(III) oxyhydroxides; the formation of the Cd‐bearing, X‐ray amorphous phase, together with Cd carbonate is the principal mechanism of Cd removal. Interestingly, Ni remains predominantly in solution due to the key role of nickel(II) carbonate, which exhibits a solubility product constant several orders of magnitude higher than the carbonates of the other metals. Traces of Ni, identified in the iron(III) precipitate, are exclusively adsorbed onto the large surface area of nanoparticles. We discuss the relationship between the crystal structure of iron(III) oxyhydroxides and the mechanism of metal removal, as well as the linear relationship observed between the rate constant and the surface area of precipitates.     

Coordination modes of N-2-(4-amino-1-methyl-5-nitroso-6-oxo-1,6-dihydropyrimidinyl) potassium L-alaninate toward Ag(I), Cd(II) and Pd(II). Crystal structure of {Ag((η4-μ3-L)]·3H2O}n,first example of a silver 3D-polymer with a pyrimidine-derivative ligand

The acid-base behaviour of the N-2-(4-amino-1-methyl-5-nitroso-6-oxo-1,6-dihydropyrimidinyl) potassium L-alaninate (KL) and its reactivity with Ag(I), Cd(II) and Pd(II) metal ions have been studied. Three solid species with formulae AgL·3H₂O, CdL₂·6H₂O and PdClL·H₂O have been obtained and characterized by IR, ¹H and ¹³C NMR spectroscopic methods and thermal, conductivity and magnetic measurements. The structure of {Ag((η⁴-μ₃-L)]·3H₂O}_n has been established by single-crystal X-ray diffraction and consists in a 3D-polymer. Within the polymer each Ag(I) ion is tetrahedrally coordinated to three differents L anions, while each ligand is coordinated in a rather unusual η⁴-μ₃ coordination mode. Spectroscopic data show a similar coordination mode for the Cd(II) complex, while for the Pd(II) one a different coordination mode is proposed.     

Surface complexation modeling of zinc sorption onto ferrihydrite

A previous study involving lead(II) [Pb(II)] sorption onto ferrihydrite over a wide range of conditions highlighted the advantages of combining molecular- and macroscopic-scale investigations with surface complexation modeling to predict Pb(II) speciation and partitioning in aqueous systems. In this work, an extensive collection of new macroscopic and spectroscopic data was used to assess the ability of the modified triple-layer model (TLM) to predict single-solute zinc(II) [Zn(II)] sorption onto 2-line ferrihydrite in NaNO(3) solutions as a function of pH, ionic strength, and concentration. Regression of constant-pH isotherm data, together with potentiometric titration and pH edge data, was a much more rigorous test of the modified TLM than fitting pH edge data alone. When coupled with valuable input from spectroscopic analyses, good fits of the isotherm data were obtained with a one-species, one-Zn-sorption-site model using the bidentate-mononuclear surface complex, (triple bond FeO)(2)Zn; however, surprisingly, both the density of Zn(II) sorption sites and the value of the best-fit equilibrium "constant" for the bidentate-mononuclear complex had to be adjusted with pH to adequately fit the isotherm data. Although spectroscopy provided some evidence for multinuclear surface complex formation at surface loadings approaching site saturation at pH >/=6.5, the assumption of a bidentate-mononuclear surface complex provided acceptable fits of the sorption data over the entire range of conditions studied. Regressing edge data in the absence of isotherm and spectroscopic data resulted in a fair number of surface-species/site-type combinations that provided acceptable fits of the edge data, but unacceptable fits of the isotherm data. A linear relationship between logK((triple bond FeO)2Zn) and pH was found, given by logK((triple bond FeO)2Znat1g/l)=2.058 (pH)-6.131. In addition, a surface activity coefficient term was introduced to the model to reduce the ionic strength dependence of sorption. The results of this research and previous work with Pb(II) indicate that the existing thermodynamic framework for the modified TLM is able to reproduce the metal sorption data only over a limited range of conditions. For this reason, much work still needs to be done in fine-tuning the thermodynamic framework and databases for the TLM.     

Syntheses,Hirshfeld surface analyses,and luminescence of four new complexes

Four Cd-based complexes with chemical formulae [Cd(L¹)₂(2,2'-Bipy)(H₂O)] (I), [Cd(L²)₂(2,2'-Bipy) · 2H₂O] (II), [Cd(L¹)₂(Phen)(H₂O)] (III), {[Cd(L¹)₂(H₂O)(4,4'-Bipy)] · 3H₂O} (IV) (HL¹ = 3-(4-hydroxyphenyl)propanoic acid, HL² = p-hydroxyphenylacetic acid, Phen = phenantroline), have been synthesized and structurally characterized (CIF file CCDC nos. 1044844 (I), 1044844 (II), 1044844 (III), 1044847 (IV)). Single-crystal X-ray analyses reveal that compounds I and III have mononuclear Cd(II) units linking by three carboxylate groups, complex II shows dinuclear motif, whereas IV exhibits 1D chain constructed by bridging 4,4'-Bipy ligand. The assistant effect of chelating N-donor ligands with 2,2'-Bipy and Phen bind and bridging 4,4'-Bipy, as well as the flexibility of carboxylate, play an important to modulate on the resulting motifs. The detailed analyses of Hirshfeld surface and fingerprint plots provide insight into the nature of non-covalent interactions in the title compounds. Furthermore, the luminescent properties of the all compounds were discussed in detail.     

Syntheses,crystal structures,and fluorescent properties of two d10 metal complexes based on 2-(benzoimidazol-yl)methyl)-1H-1,2,4-triazole and 1,3,5-benzenetricarboxylate

Two d¹⁰ metal complexes, {[Zn(Hbtc)(bmt)]·DMF·5H₂O} _n (1) and {[Cd(Hbtc)(bmt)]·0.5DMF·0.5H₂O} _n (2) (H₃btc?=?1,3,5-benzenetricarboxylic acid, bmt?=?2-((benzoimidazol-yl)methyl)-1H-1,2,4-triazole), have been synthesized under solvothermal conditions by employing bmt and H₃btc. Single-crystal X-ray diffraction shows that Zn(II) ions are connected by bmt with bidentate-bridging coordination and by 1,3,5-benzenetricarboxylate with bis-monodentate coordination leading to the 2D structure of 1. Complex 2 exhibits a 2D layer structure, in which bmt coordinate tridentate-bridging to Cd(II) and 1,3,5-benzenetricarboxylates coordinate to Cd(II) unidentate/chelating. Photoluminescence and thermogravimetric analyses of the two complexes are investigated.     

石英与水溶液作用的界面反应特征

矿物表面因存在有各种悬空键 ,而形成了表面活性官能团 ,称作“表面位”。对石英来说 ,表面氧离子可以与水中Ｈ+和ＯＨ- 离子反应 ,使表面产生荷电性。研究表明[1 ,2 ] ,石英对二价金属离子的吸附反应遵循Ｆｒｅｕｄｌｉｃｈ方程 ,本文在分析石英表面位及其质子化反应、表面位与重金属离子反应的基础上 ,进一步探讨石英与水溶液作用的界面反应特征及其影响因素。1　实验材料与方法石英粉末样品用王水煮洗 ,后用纯净水浸洗至无ＡｇＣｌ,过滤、1 1 0℃烘干、450℃煅烧 1 2ｈ。经ＮＯＶＡ 1 0 0 0ＶＥＲ3.7自动表面分析仪 (Ｎ2 ＢＥＴ法 )测定…     

2-line ferrihydrite: synthesis, characterization and its adsorption behaviour for removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions

Nano-structured 2-line ferrihydrite was synthesized by a pH-controlled precipitation technique at 90 °C. Chemical, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman analyses confirmed the sample to be 2-line ferrihydrite. The nano nature of the prepared sample was studied by transmission electron microscopy (TEM). The surface area obtained by the Brunauer-Emmett-Teller (BET) method was 175.8 m(2) g(-1). The nanopowder so obtained was used to study its behaviour for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. The relative importance of experimental parameters such as solution pH, contact time and concentration of adsorbate on the uptake of various cations was evaluated. By increasing the pH from 2.0 to 5.5, adsorption of the four cations increased. The kinetics parameters were compared by fitting the contact time data to both linear as well as non-linear forms of pseudo-second-order models. Linear forms of both Langmuir and Freundlich models fitted the equilibrium data of all the cations except for Pb(II) which was also fitted to the non-linear forms of both the models as it gave a low R(2) value of 0.85 for the Langmuir model. High Langmuir monolayer capacities of 366, 250, 62.5 and 500 mg g(-1) were obtained for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. Presence of chloride or sulfate had an adverse effect on cation adsorption. The interactive effects on adsorption from solutions containing two, three or four cations were studied. Surprisingly no Cd(II) adsorption was observed in Pb(II)-Cd(II), Pb(II)-Cd(II)-Zn(II) and Pb(II)-Cd(II)-Cu(II)-Zn(II) systems under the studied concentration range. The overall loading capacity of the adsorbent decreased in mixed cation systems. Metal ion loaded adsorbents were characterized by XRD, FTIR and Raman techniques. The high adsorption capability of the 2-lines ferrihydrite makes it a potentially attractive adsorbent for the removal of cations from aqueous solutions.     

Syntheses,crystal structures,and fluorescent properties of two 2-D Cd(II) complexes based on 2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate

Two complexes formulated as {[Cd(btec)_0.5(tmb)H₂O]·4H₂O}_n (1) and {[Cd(H₂btec)(tmb)(H₂O)]·2H₂O}_n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, tmb?=?2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole) have been synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Single crystal X-ray diffraction shows that 1 has a 2-D layer structure in which tmb bridges and all of the carboxylates from 1,2,4,5-benzenetetracarboxylate chelate. In 2 Cd(II) ions are bridged by monodentate carboxylates leading to a 2-D layer structure with all tmb ligands coordinated monodentate to Cd(II), hanging at two sides of the layers. Complexes 1 and 2 are further extended to 3-D supramolecular structures by hydrogen bonding interactions. Luminescent properties have been investigated in the solid state at room temperature.     

Cadmium ion adsorption on different carbon adsorbents from aqueous solutions. Effect of surface chemistry, pore texture, ionic strength, and dissolved natural organic matter

Adsorption of Cd(II) species at pH = 5 was studied on three carbon adsorbents: granular activated carbon, activated carbon fiber, and activated carbon cloth. As-received and oxidized adsorbents were used. Cd(II) adsorption greatly increased after oxidation due to the introduction of carboxyl groups. The use of a buffer solution to control the pH introduced some changes in the surface chemistry of carbons through the adsorption of one of the compounds used, biphthalate anions. The increase in ionic strength reduced Cd(II) uptake on both as-received and oxidized carbons due to a screening of the electrostatic attractions between the Cd(II) positive species and the negative surface charge, which in the case of as-received carbons derived from the biphthalate anions adsorbed and in the oxidized ones from the carboxyl groups. Tannic acid was used as a model compound for natural organic matter. Its adsorption was greatly reduced after oxidation, and most of the carbon adsorbents preadsorbed with tannic acid showed an increase in Cd(II) uptake. In the case of competitive adsorption between Cd(II) species and tannic acid molecules, there was a decrease in Cd(II) uptake on the as-received carbon whereas the contrary occurred with the oxidized carbons. These results illustrate the great importance of carbon surface chemistry in this competitive adsorption process. Finally, under all experimental conditions used, when the adsorption capacity of carbons was compared under the same conditions it increased in the following order: granular activated carbon < activated carbon fiber < activated carbon cloth.     

Study of pH-dependent charges of soils by surface acid-base properties

The pH-dependent charges of Hungarian soils have been studied via surface acid-base properties. The intrinsic stability constants of protonation and deprotonation processes, as well as the concentration of surface sites, have been determined by surface complexation modeling. The protonation and deprotonation constants have been nearly the same for most soils. There is a relation between the concentration of surface sites and composition, expect for the freshly deposited soils with high primary silicate content. The results show that the concentrations of silanol and aluminol sites are different for each soil, the intrinsic stability constants of protonation and deprotonation processes, however, are nearly the same within experimental error. This can only be explained if these stability constants are real thermodynamic equilibrium constants. The fact that these constants are nearly the same supports the conclusion that we succeeded in excluding all processes that would disturb the measurements. The parameters characteristic of the edge sites of the soils are of two types: (a) the parameters depending on the quality and composition of the soils, (i.e.), the concentration of surface sites; (b) the parameters depending on the thermodynamically well-defined acid-base processes, independent of soil composition.     

Preparation of silicon-doped ferrihydrite for adsorption of lead and cadmium: Property and mechanism

In this study, Si-doped ferrihydrite (Si-Fh) was successfully synthesized by a simple coprecipitation method for removal of heavy metals in water. Subsequently, the physicochemical properties of Si-Fh before and after adsorption were further studied using several techniques. The Si-Fh exhibited good adsorption capacity for heavy metal ions such as Pb(II) and Cd(II). The maximum adsorption capacities of lead and cadmium are respectively 105.807, 37.986 mg/g. The distribution coefficients of the materials for Pb(II) and Cd(II) also showed a great affinity (under optimal conditions). Moreover, it was found that the adsorption fit well with the Freundlich isotherm and pseudo-second-order kinetic model which means this was a chemical adsorption process. It can be conducted from both characterization and model results that adsorption of Pb(II) and Cd(II) was mainly through the complexation interaction of abundance oxygen functional groups on the surface of Si-Fh. Overall, the Si-Fh adsorbents with many superiorities have potential for future applications in the removal of Pb(II) and Cd(II) from wastewater.     

Syntheses,structures, and properties of two 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and polycarboxylate ligands

Two 2-D Cd(II) complexes, {[Cd(imb)(bdc)(H₂O)]·CH₃OH}_n (1) and {[Cd(imb)(Hbtc)(CH₃OH)]·2H₂O·CH₃OH}_n (2), have been synthesized by reactions of CdCl₂·2.5H₂O with 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,3-benzenedicarboxylic acid (H₂bdc) or 1,3,5-benzenetricarboxylic acid (H₃btc). Single-crystal X-ray diffraction shows that 1 possesses an infinite 2-D layered structure in which all the carboxylates chelate Cd(II) and imb bridge Cd(II) ions. Complex 2 also features an infinite 2-D layered structure and imb ligands also bridge Cd(II) ions, but two carboxylates of each 1,3,5-benzenetricarboxylate coordinate to Cd(II) in monodentate or chelating mode, leaving the third one, which is not deprotonated, uncoordinated. IR spectra, fluorescent properties, and thermogravimetric analyses of both complexes have been investigated.     

Protolytic surface reactions of a fluorapatite-maghemite mixture in aqueous suspension

Synthetically prepared maghemite and fluorapatite, characterized with BET, SEM, XRD, FT-IR, and FT-Raman, are used to investigate the protolytic properties and surface characteristics in a mixed system of maghemite and fluorapatite by means of potentiometric titrations and surface complex modeling. Titrations were performed in the pH range of 7.3-10.5 at 25 +/- 0.2 degrees C in ionic media of 0.10 mol dm(-3) NaNO3 with 0.0100 mol dm(-3) HNO3 and 0.0100 mol dm(-3) NaOH used as titrants. The constant capacitance model (CCM) was applied to interpret the titration data. Two models with different surface equilibria were tested. In the first model, the mixed system was treated as a one-component system with a total surface area of 40.04 +/- 5.2 m2 g(-1) without any consideration to the subsystems. The surface equilibria, triple bond XOH + H+ <==> triple bond XOH2+, beta(s)(-11)(int) = 6.74 +/- 0.07; XOH <==> triple bond XO- + H+, beta(s)(-11)(int) = -7.75 +/- 0.07, were found to represent an accurate model for the system, and the specific capacitance was optimized to 2.0 F m(-2). The number of active surface sites N(s) was found to be 1.2 sites nm(-2). This model has, however, no relation to the subsystems of maghemite and fluorapatite. The second model is related to the subsystems and displays the surface equilibria, triple bond S2OH<==> triple bond S2O- + H+, beta(s)(-101)(int) = -9.12 +/- 0.01; triple bond FeOH + H+<==> triple bond FeOH2+, lg beta(s)(-11)(int) = 6.80 +/- 0.01; triple bond FeOH<==>FeO- + H+, beta(s)(-11)(int) = -7.77 +/- 0.01, where S2OH is related to fluorapatite and FeOH is representing maghemite. Fluorapatite corresponds to the dominating active surface in the system. The specific capacitance was optimized to 18 F m(-2). The N(s) values were found to be 2.27 sites nm(-2) for fluorapatite and 0.80 sites nm(-2) for maghemite. The N(s) values together with evidence from the FT-Raman and SEM investigations reveal that interactions between maghemite and fluorapatite surfaces occur during the titration. The acid-base properties and surface characteristics of the subsystems maghemite-H+ and fluorapatite-OH- using the CCM have been published earlier.     

Synthesis,characterization, DNA binding/cleavage,and anticancer and antimicrobial activities: Nano-sized Co(II) and Cd(II) complexes and their use as a precursor for CoO and CdO nanoparticles

In the search of effective bioactive compounds, Co(II) ( C1 ) and Cd(II) ( C2 ) complexes of the type [M(FMAPIMP)(H₂O)Cl].nH₂O (where M = Co(II); n = 2, Cd(II); n = 3, and FMAPIMP = ligand[2-((E)-((2-(((E)-furan-2-ylmethylene)amino)phenyl)imino)methyl)phenol]) were synthesized and characterized using elemental analysis, UV–Vis., cyclic voltammetry, Fourier-transform infrared (FT-IR), nuclear magnetic resonance, and mass spectral studies. The thermal stability of nano-sized Co(II) and Cd(II) complexes was studied using thermogravimetric analysis (TGA). Cobalt and cadmium oxides were synthesized using cobalt and cadmium nanoparticle (NP) structure Schiff base complexes as the raw material after calcination for 5 h at 600 °C. According to the results, Co(II) and Cd(II) complexes with mole ratio 1:1 of metal: H-FMAPIMP which octahedral are the most probable geometry for it. On the contrary, synthesized C1 and C2 NPs were used as suitable precursors for the preparation of CoO and CdO NPs. The obtained NPs were characterized using FT-IR, UV–Vis., TGA, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy techniques. PXRD analysis revealed that the obtained oxides were crystalline and corresponded to CoO and CdO phases. Crystal size, shape, and morphology were determined using SEM and TEM. H-FMAPIMP and its two complexes ( C1 and C2 ) were tested against human ovarian cancer cell line (PA-1). The synthesized Co(II) and Cd(II) complexes exhibited enhanced activity against the tested bacterial (Staphylococcus aureus and Escherichia Coli) and fungal strains (Candida albicans and Aspergillus fumigatus) as compared to H-FMAPIMP. The results of the DNA-cleavage activity indicated that the ligand and its two complexes can cleave calf thymus-DNA at different degrees. Further, antituberculosis activity was performed using microplate alamarBlue assay. Among all these synthesized compounds, C1 exhibited good cleaving ability compared to the newly synthesized C2 . Finally, the geometry of H-FMAPIMP and its Co(II) and Cd(II) complexes was optimized using molecular modeling.     

基于半刚性乳酸衍生物的单一手性配位聚合物的合成、 结构与性质

在溶剂热反应条件下, 用预先合成的乳酸衍生物(R)-H₂CBA和(S)-H₂CBA分别与含氮辅助配体(E)-1,2-二(4-吡啶基)乙烯(DPEE)和1,4-二(1H-咪唑-1-基)苯(1,4-DIB)组合, 制备出2对不同结构的单一手性配位聚合物[Cd₂((R)-CBA)₂(DPEE)(H₂O)₂]_n(1-D), [Cd₂((S)- CBA)₂(DPEE)(H₂O)₂]_n(1-L), [Cd((R)-CBA)(1,4-DIB)]·H₂O(2-D)和[Cd((S)-CBA)(1,4-DIB)]·H₂O(2-L). 其中1-D和1-L是由梯形Cd-CBA链和DPEE配体连接成的二维框架结构; 而2-D和2-L是三维超分子框架结构, 包含3种不同类型的对映手性螺旋链. 对上述化合物进行了粉末X射线衍射、 热重分析和圆二色谱分析, 并对其荧光性质进行了讨论.     

Cadmium(II) N-acetylcysteine complex formation in aqueous solution

The complex formation between Cd(II) ions and N-acetylcysteine (H(2)NAC) in aqueous solution was investigated using Cd K- and L(3)-edge X-ray absorption and (113)Cd NMR spectroscopic techniques. Two series of 0.1 M Cd(II) solutions with the total N-acetylcysteine concentration c(H2NAC) varied between 0.2-2 M were studied at pH 7.5 and 11.0, respectively. At pH = 11 a novel mononuclear [Cd(NAC)(4)](6-) complex with the average Cd-S distance 2.53(2) ? and the chemical shift δ((113)Cd) = 677 ppm was found to dominate at a concentration of the free deprotonated ligand [NAC(2-)] > 0.1 M, consistent with our previous reports on cadmium tetrathiolate complex formation with cysteine and glutathione. At pH 7.5 much higher ligand excess ([HNAC(-)] > 0.6 M) is required to make this tetrathiolate complex the major species. The (113)Cd NMR spectrum of a solution containing c(Cd(II)) = 0.5 M and c(H2NAC) = 1.0 M measured at 288 K showed three broad signals at 421, 583 and 642 ppm, which can be attributed to CdS(3)O(3), CdS(3)O and CdS(4) coordination sites, respectively, in oligomeric Cd(II)-NAC species with single thiolate bridges between the cadmium ions.     

Chemistry of Thiobenzoates: Syntheses, Structures, and NMR Spectra of Salts of [M(SOCPh)(3)](-) (M = Zn, Cd, Hg)

The salts (Ph(4)E)[M(SOCPh)(3)] (M = Zn, Cd, or Hg; E = P or As) are produced by the reaction of Zn(NO(3))(2).6 H(2)O, Cd(NO(3))(2).4H(2)O or HgCl(2) with Et(3)NH(+)PhCOS(-) and (Ph(4)E)X (E = P, X = Br; E = As, X = Cl) in aqueous MeOH in the ratios M(II):PhCOS(-):Ph(4)E(+) = 1:>/=3:>/=1. The crystal structures of (Ph(4)P)[Zn(SOCPh)(3)] (1), (Ph(4)As)[Cd(SOCPh)(3)] (2) and (Ph(4)P)[Hg(SOCPh)(3)] (3) have been determined by single-crystal X-ray diffraction experiments. Crystal data for 1: triclinic; space group P&onemacr;; Z = 2; a = 10.819(2) ?, b = 13.219(3) ?, c = 15.951(3) ?; alpha = 101.75(2) degrees, beta = 97.92(1) degrees, gamma = 109.18(2) degrees. Crystal data for 2: triclinic; space group P&onemacr;; Z= 2; a = 10.741(2) ?, b = 13.168(2) ?, c = 15.809(2) ?; alpha = 101.00(1) degrees, beta = 97.65(1) degrees, gamma = 109.88(1) degrees. Crystal data for 3: monoclinic; space group P2(1)/n; Z = 4; a = 13.302(2) ?, b = 14.276(2) ?, c = 21.108(2) ?; beta = 90.92(1) degrees. The compounds 1 and 2 are isomorphous and isostructural. In the anions [M(SOCPh)(3)](-) the metal atoms have trigonal planar coordination by three sulfur atoms. The metal atoms are further more weakly coordinated intramolecularly to one (M = Hg) or two (M = Zn, Cd) thiobenzoate oxygen atom(s). Using the Bond Valence approach it is found that the contribution of M.O bonding to the total bonding is in the order Cd > Zn > Hg. The metal ((113)Cd, (199)Hg) NMR signals of [M(SOCPh)(3)](-) (M = Cd, Hg) are more shielded than those found for MS(3) kernels in thiolate complexes, a difference attributed to the M(.)O bonding in the thiobenzoate complexes. The (113)Cd resonance of [Cd(SOCPh)(3)](-) in dilute solution is in the region anticipated from dilution data for [Na(Cd{SOCPh}(3))(2)](-).     

Synthesis of new ionic β-cyclodextrin polymers and characterization of their heavy metals retention

In this study, a new aqueous insoluble ionic β-cyclodextrin polymer (PYR), synthesized by reaction of β-cyclodextrin with pyromellitic anhydride [1], is characterized by IR spectroscopy, showing typical cyclodextrin and carboxylic absorptions. pH-metric titrations of the acidic functions with standard NaOH solutions followed by a refinement of protonation constants, with specific software for equilibrium in solution, have been performed. Through this approach, the pK _a values of the functional groups have been calculated. The complexation capabilities of PYR towards metal ions [Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), Pt(IV), Tl(I), and U(IV)] have been evaluated in aqueous solution (pH 3–5). The retention is mainly pH dependent and higher than 70% for Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II) and U(IV). For Tl(I) and Pt(IV) the retention is about 60% and 40% respectively.     

A New Electrochemical Method for the Determination of Proteins with Cupferron‐Cadmium(II) Complex

A new electrochemical method was proposed for the determination of trace amounts of proteins based on the cupferron (Cup) and cadmium(II) complex [Cup‐Cd(II)] as the voltammetric probe. In the selected pH 6.5 Britton–Robinson (B–R) buffer solution, Cup can interact with Cd(II) to form a stable complex of [Cup‐Cd(II)], which had a sensitive linear sweep voltammetric reductive peak at ?0.654 V (vs. SCE). The addition of human serum albumin (HSA) into [Cup‐Cd(II)] complex solution could greatly decrease the reductive peak current without the change of the reductive peak potential, which indicated that HSA could interact with [Cup‐Cd(II)] complex to form a supramolecular biocomplex. The interaction mechanism was discussed and the decrease of reductive peak current was proportional to the concentration of HSA, which could be further used for the proteins determination. The optimal conditions of the binding reaction and the electrochemical detection were carefully investigated. Under the optimal conditions a new quantitative determination method for different kinds of proteins such as HSA, bovine serum albumin (BSA) and bovine hemoglobin (BHb) etc. was developed. The proposed method was simple, practical and relatively free from the interferences of coexisting substances, and it was further applied to the samples determination with satisfactory results. The binding constant (β_s) and the binding number (m) of HSA with [Cup‐Cd(II)] complex were calculated by the voltammetric data with the results as β_s=1.12×10⁶ and m=1.