Metal Ion Binding Ability Research Articles

Synthesis and metal ion binding activity of methyl 12-amino-13-nitro-7-oxo dehydrodeisopropylabietate derivatives

Starting from dehydrobaietic acid with the analogous structure of carnosic acid, the intermediate methyl 12-bromo-13-nitro-7-oxo dehydrodeisopropylabietate was synthesized through methylation, bromination, carbonylation, and nitration. Subsequently, the coupling of methyl 12-bromo-13-nitro-7-oxo dehydrodeisopropylabietate with aliphatic or aromatic primary amine by Ullmann condensation reaction produced a series of methyl 12-imino-13-nitro-7-oxo dehydrodeisopropylabietate derivatives. In order to probe their antioxidant effects through metal ion chelation mechanism, the metal ion binding abilities on Cu2+ and Fe2+ of these compounds were studied using fluorescence quenching method. The results indicated that each compound showed obvious chelation activity with the binding constants (K A) of the 102 L mol−1 order of magnitude, which implied its potential pharmacology application as antioxidant by the inhibition of Feton reaction through chelation with Cu2+ and Fe2+.

Miniemulsion polymers as solid support for transition metal catalysts

A pentadentate salen-type ligand was immobilized in a poly[(styrene)]- co-(butyl acrylate)] matrix by miniemulsion polymerization. The obtained polymer beads revealed a particle size of 50 nm in the dry state by transmission electron microscopy. Dynamic light scattering experiments in methanol and water showed a solvent-dependent average particle size with a mean particle diameter of up to 233 nm in methanol. These results provide valuable insights for the optimization of macromolecular oxidation catalysts and their future use as enzyme-like entities in aqueous media. The particle stability was demonstrated over a wide pH range (3–11) by gel permeation chromatography, and initial results for the metal ion binding ability were obtained.

Synthesis of Novel Molecular Clips via Click Chemistry Based on Diethoxy carbonyl Glycoluril

A novel class of molecular clips based on diethoxycarbonyl glycoluril was synthesized via click chemistry. Seven different arylacetylenes were used in this research, and all reaction products gave satisfying ¹H NMR, ¹³C NMR, HRMS, and IR spectra. The structure and conformation of 7a were further confirmed by single-crystal X-ray diffraction. A primary study on the metal-ion binding ability of 7f showed that its fluorescence was obviously quenched by Fe³+, Ag+, and Cu²+ among metal ions examined.

Azacrown-oxabridged macrocycle: a novel hybrid fluorogenic chemosensor for transition and heavy metal ions

A novel hybrid of azacrown ether-oxabridged fluorogenic chemosensor (1) has been synthesized: the metal ion binding ability of the hybrid molecule shows higher affinity towards transition metal ion Zn(2+) and heavy metal ion Hg(2+) compared to the parent azacrown ether which shows poor metal ion selectivity: the binding modes of the Zn(2+) and Na(+) towards have been discussed.

The two distinctive metal ion binding domains of the wheat metallothionein Ec-1

Metallothioneins are small cysteine-rich proteins believed to play a role, among others, in the homeostasis of essential metal ions such as Zn(II) and Cu(I). Recently, we could show that wheat E(c)-1 is coordinating its six Zn(II) ions in form of metal-thiolate clusters analogously to the vertebrate metallothioneins. Specifically, two Zn(II) ions are bound in the N-terminal and four in the C-terminal domain. In the following, we will present evidence for the relative independence of the two domains from each other with respect to their metal ion binding abilities, and uncover three intriguing peculiarities of the protein. Firstly, one Zn(II) ion of the N-terminal domain is relative resistant to complete replacement with Cd(II) indicating the presence of a Zn(II)-binding site with increased stability. Secondly, the C-terminal domain is able to coordinate an additional fifth metal ion, though with reduced affinity, which went undetected so far. Finally, reconstitution of apoE(c)-1 with an excess of Zn(II) shows a certain amount of sub-stoichiometrically metal-loaded species. The possible relevance of these finding for the proposed biological functions of wheat E(c)-1 will be discussed. In addition, extended X-ray absorption fine structure (EXAFS) measurements on both, the full-length and the truncated protein, provide final evidence for His participation in metal ion binding.

Water‐soluble Polyelectrolytes Contaning Sulfonic Acid Groups with Metal Ion Binding Ability by Using the Liquid Phase Polymer Based Retention Technique

AbstractWater‐soluble polyelectrolytes from 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (APSA) were obtained by radical polymerization with different comonomers which contain weak acid and neutral groups. These copolymers were investigated as polyelectrolytes and polychelatogens, in view of their metal ion binding properties using the liquid‐phase polymer‐based retention (LPR) technique under different experimental conditions. The metal ions investigated were: Ag(I), Co(II), Cu(II), Zn(II), Cd(II), and Pb(II). APSA allowed increase metal ion interaction of weak acid, meanwhile did not improve the metal ion interaction of neutral monomers at these experimental conditions. Results indicated that retention capability depended strongly on the structure of the polyelectrolyte, arrangement of comonomers at main chain, pH, and the filtration factor, Z.

Inositol derived crown ethers: effect of auxiliary protecting groups and the relative orientation of crown ether oxygen atoms on their metal ion binding ability

The binding constants of crown ethers prepared from tetra- O-substituted myo- and scyllo-inositol derivatives and 2- O-substituted myo- and scyllo-inositol-1,3,5-orthoformates, with metal picrates show that the O-substituents and the relative orientation of the crown ether oxygen atoms contribute significantly to the binding of crown ethers with metal ions. In particular, the binding efficiency of myo-inositol derived crown ethers to silver and potassium ions could be enhanced by introducing benzyl ethers in the inositol ring. Hence binding efficacy and selectivity of metal ions to inositol derived crown ethers can be tuned by varying substituents on the myo-inositol ring and/or the relative orientation of crown ether oxygen atoms.

Metal Ion Biosorption Potential of Lignocellulosic Biomasses and Marine Algae for Wastewater Treatment

The metal ion-binding abilities of six lignocellulosic biomasses obtained from agro-industrial products and sustainable plantations, as well as of two red and one green marine algal species, were examined in a comparative manner to ascertain their potential as biosorbents of heavy metals from low concentration wastewater. Dilute single-solute solutions of cadmium and nickel ions (≤ 1 mM) were used as models. All the biomaterials showed appreciable Cd(II) ion biosorption which was strongly dependent on the dosage used. The maximum Cd(II) ion biosorption capacities (XmL), as estimated from the experimental isotherms using the Langmuir model, indicated that the red algae (XmL = 0.26–0.52 mmol/g) and the lignocellulosic biomasses with larger lignin contents (XmL = 0.17–0.20 mmol/g) possessed the greatest potential. This behaviour also applied to Ni(II) ion biosorption, although the biomaterials proved to be less effective in this case, especially towards low dosage. Comparison of the Cd(II) ion equilibrium so...

Selective heavy metal receptor functional phthalocyanines bearing thiophenes: Synthesis, characterization, spectroscopy and electrochemistry

Soft metal ion receptor 2,9,16,23-tetrakis-6-(-thiophene-2-carboxylate)-hexylthio-phthlocyaninato zinc(II) and cobalt(II) complexes derived from 6-(3,4-dicyanophenylthio) hexylthiophene-2-carboxylate have been prepared as an isomeric mixture via cyclotetramerization reactions. The complexes have been fully characterized by elemental analysis, FTIR, 1H and 13C NMR, MS (ESI and MALDI-TOF) and by UV–vis spectral data. Soft metal ion binding ability of the complexes with Ag I, Pd II, Hg II and Cd II has been evaluated by UV–vis spectroscopic titration technique. Cyclic and differential pulse voltammetries show that while Zn(II)Pc gives up to two ligand-based reduction and one ligand-based oxidation processes having diffusion-controlled reversible electron transfer properties, Co(II)Pc represents one ligand-based and one metal-based oxidation and one metal-based and one ligand-based reduction processes having diffusion-controlled reversible electron transfer characters. Assignments of the redox couples of Co(II)Pc are confirmed by spectroelectrochemical measurements.

Synthesis and Alkaline Metal Ion Binding Ability of New Steroid Dimers Derived from Cholic and Lithocholic Acids

The synthesis and NMR spectra of steroid dimers being derivatives of cholic and lithocholic acid methyl esters, in which the steroid residues are linked by the terephthaloyl spacer, are described. The complexing ability of the dimers towards alkaline metal cations has been studied by the electrospray mass spectrometry. Cholic acid derivatives show affinity toward metal cations and anions. Binding of metal cations by methyl lithocholate dimer has not been detected.

Oxymethylcrowned chromene: photoswitchable stoichiometry of metal ion complex and ion-responsive photochromism

Chromene derivatives bearing oxymethyl-12-crown-4 ( 1 ), -15-crown-5 ( 2 ), -18-crown-6 ( 3 ) ether moieties, and non-cyclic analogue ( 4 ) were synthesized, and their metal ion binding properties and photochromism were examined. NMR titration with alkali metal ions revealed that 1 formed a 1:2 complex (metal ion: ligand) with Na +, while Li + afforded a 1:1 complex of 1 . In cases of K + and Rb +, the complexes were a mixture of 1:1 and 1:2 complexes, but the formation of 1:1 complex was observed again with Cs +. Under UV irradiation, however, the complex stoichiometry of 1 with all alkali metal ions was 1:1. As a comparison of NMR spectra between the Li + and Na + complexes of 1 indicated considerable upfield shift for the chromene moiety of the Na + complex, π–π stacking of the chromene moiety seems to induce formation of the 1:2 complex. These results indicate that the chromene moiety is not only to show photochromism but also to induce aggregation to form the 1:2 complex resulted in switching of the complex stoichiometry by UV irradiation. The formation of 1:2 complex appeared only with 1 because flexibility of the crown moieties for 2 and 3 interfered the formation of 1:2 complex. Studies on photochromism in the presence of a metal ion demonstrated that the chromene derivatives bearing crown ether moieties show ion-responsive photochromism depending on the metal ion binding ability of their crown ether moieties.

Metal ion-binding ability of tetrapeptides containing alpha-aminoisobutyric acid.

alpha-Aminoisobutyric acid (Aib), one of the Calpha,alpha-disubstituted glycines, is a sterically hindered amino acid that acts as a conformational constraint in peptides. However, studies for the application of the ability of Aib to control conformation are quite few. The paper focuses on the molecular recognition ability of acyclic oligopeptides containing Aib. Liquid-liquid extraction of nine kinds of metal ions from aqueous layers to nonpolar organic layers with acyclic tetrapeptides, X-Trp-Xaa2-Gly-Xaa4-NH-Ar (X = H or C6H5CH2OCO (Z), Xaa2 = Aib or Gly, Xaa4 = Leu or Ala, Ar = phenyl or 3,5-dimethylphenyl) was examined using picrate as the anion of ion pairs. The extraction behaviour of the metal ions with the tetrapeptides was investigated in the pH range from 3 to 9. In the case of basic pH regions, Cu(II) and Ag(I) were effectively extracted with Trp-Aib-Gly-Leu-NH-Ar. Pd(II) was specifically extracted with Trp-Aib-Gly-Leu-NH-Ar in acidic pH regions. The extraction percent (%E) of the peptide host, which has a 3,5-dimethylphenyl group, was even larger than that of the host, which has a phenyl group. Moreover, Pd(II) was extracted with a peptide host which has Leu and a 3,5-dimethylphenyl group in the absence of picrate as the anion of ion pairs. The free alpha-amino group, the turn conformation and the hydrophobicity of peptide molecules were important factors for the extraction of the metals.

Preparation and adsorption properties of resins containing amine, sulfonic acid, and carboxylic acid moieties

AbstractCompletely water‐insoluble resins containing amine, carboxylic acid, and sulfonic acid as ligand groups were synthesized by radical polymerization in solution. The yield was higher than 97%. The resins were characterized by FTIR spectroscopy and thermal analysis. The metal ion retention properties at different pH values were investigated by a batch method. Metal ions studied were: Cu(II), Cd(II), Zn(II), Hg(II), Pb(II), and Cr(III). The metal ion binding ability depended strongly on the pH. The retention properties were also tested under competitive conditions. Elution of the metal ion was investigated in acid medium at different concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 700–705, 2003

Ion‐Responsive Photochromic Materials; Crowned Spirobenzopyrans

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chromened t-butylcalix[4]arenes: cooperation effect of chromene and calixarene moieties on photochromism and metal-ion binding ability

Novel t-butylcalix[4]arenes bearing several chromene molecules were synthesized, and their photochromism and metal-ion binding ability were examined with alkali and alkaline-earth metal ions. While the metal-ion binding ability of the t-butylcalix[4]arene moiety facilitated the photoisomerization of the chromene moiety to a great extent, the chromene moiety influenced the metal-ion binding ability of the t-butylcalix[4]arene moiety through lariat effect. Therefore, the metal-ion that induced the most facilitated photoisomerization of the chromene moiety was shifted drastically from Li + to Ba 2+ with the increase of the incorporated chromene number. Even without metal ions, the interaction among the chromene moieties derived from the cone-conformation of the t-butylcalix[4]arene moiety also facilitated the photoisomerization.

イオン応答性フォトクロミック化合物；クラウン化スピロベンゾピラン

Various spirobenzopyrans bearing crown ether moieties, namely, crowned spirobenzopyrans, were synthesized and their photochromism was examined in the presence of metal ions. The crowned spirobenzopyrans show facilitated photoisomerization reflecting not only the metal-ion binding ability of the crown ether moiety but also the metal-ion affinity of the phenolate anion moiety in the merocyanine form. When the interaction of metal-ion with the phenolate anion moiety is strong enough, thermal isomerization is observed. Furthermore, this interaction can induce negative photochromism upon UV irradiation. Thus, positive and negative photochromism switching of crowned spirobenzopyrans is possible through the interaction control of metal-ion with the phenolate anion and crown ether moiety.

Synthesis and characterization of a catechol-terminated alkanethiolate monolayer adsorbed on gold

Structural, redox, and metal ion binding characterizations of the monolayer formed by the chemisorption of 3,4-dihydroxyphenethyl mercaptan (DHPM) on gold are described. This system was explored as a model for investigations of surface-immobilized molecules that contain redox-transformable coordination sites for binding metal ions from solution. The characterizations were carried out using infrared reflection spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and long optical pathlength thin-layer spectroscopy. The XPS data show that this monolayer adsorbs as a thiolate, and the IRS results indicate that the average orientation of the aromatic ring plane is close to the surface normal. Cyclic voltammetry reveals that the pendant catechol/quinone undergoes the expected two-electron, two-proton redox transformation; however, the oxidized form of the couple is unstable, particularly in alkaline aqueous solutions. A determination of Cu(II) binding ability to the surface-immobilized catechol moieties, using a long optical pathlength thin-layer cell to follow the depletion of Cu(II) from solution, indicated that the complexation of the metal was not substantially different from that for the solution form of catechol. The instability of the oxidized form of the ligand, nevertheless, precluded an assessment of its metal ion binding ability. An approach using these data for estimating the conditional formation constant for the surface complexation reaction is also developed.

Poly(N,N?-dimethylacrylamide-co-acrylic acid): Synthesis, characterization, and application for the removal and separation of inorganic ions in aqueous solution

The synthesis of poly (N,N′-dimethylacrylamide-co-acrylic acd) under different feed molar ratios was carried out by radical polymerization. Both homopolymers were also synthesized to compare the metal ion binding abilities. All polymers were water-soluble and were characterized by FTIR, 1H-NMR, 13C-NMR, and TGA. The metal complexing properties for the metals Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Hg(II), Cr(III), and Fe(III) in the aqueous phase were investigated using the liquid-phase polymer-based retention (LPR) method. The metal ion interactions with the hydrophilic polymer were determined as a function of pH and the filtration factor. According to the interaction pattern obtained, the metal ions form the most stable complexes with the copolymer poly(N,N′-dimethylacrylamide-co-acrylic acid) within the pH range 5–7. Hg(II) was not retained at all the pH ranges investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 93–100, 1998

Ability of Immobilized Cyanobacteria to Remove Metal Ions From Solution and Demonstration of the Presence of Metallothionein Genes in Various Strains

Synechococcus sp. PCC 7942 has the ability to grow in mass quantity under ideal conditions; such an ability provides usable biomass at a minimal effort. Using lyophilized biomass grown under normal conditions, Synechococcus was tested for its potential to bind metal ions from solution. Batch experiments have determined the optimum binding pH, time dependency, and metal binding capacities for copper(II), lead(II), nickel(II), cadmium(II), chromium(III), and chromium(VI), along with desorption of the metal bound. The biomass studied showed an affinity for five of the metal ions, with an optimum binding at pH 5. Time dependency studies showed that this cyanobacterium had rapid binding, while capacity experiments showed this cyanobacterial strain to bind 11.3 mg of copper(II) per gram of biomass, 30.4mg of lead(II) per gram of biomass, 3.2 mg of nickel(II) per gram of biomass, 7.2 mg of cadmium (II) per gram of biomass, and 5.4 mg of chromium (III) per gram of biomass. More than 98% of copper(II), lead(II), and nickel(II) metal ions were recovered, while over 50 % of cadmium(II) and chromium(III) were recovered when treated with 0.1M HCl. The biomass was immobilized in a silica polymer and tested for its binding ability under flow conditions. Using 0.1mM concentrations of the previously indicated metals, individual experimental results showed an average of 143 mg/L copper(II), 1456 mg/L lead(II), 142 mg/L nickel(II), and 529 mg/L cadmium(II) bound by the immobilized biomass. Treatment with 0.2M HCl resulted in nearly 100% recovery for both copper(II) and lead(II) from the column, 79% recovery of cadmium(II), while recovery for nickel(II) was 42%. Experiments were conducted to determine if many cycles of metal binding- stripping by the immobilized biomass were possible. Further, attempts were made to demonstrate the presence of metallothioneins in various strains of cyanobacteria which may serve as defense mechanisms against metal ion toxicity. Such proteins may be used to develop engineered strains of cyanobacteria with increased metal ion binding ability. Synechococcus can eventually be used as a source for a novel approach in using biosystems to remediate contaminants from solution and making those contaminants available to industry through an environmentally friendly biofiltration system.

Synthesis, characterization, and polychelatogenic properties of poly(acrylic acid-co-acrylamide)

The radical copolymerization of acrylic acid with acrylamide was carried out at different monomer ratios in solution (DMF) at 60°C. The corresponding homopolymers were also synthesized to compare their metal ion binding abilities. All the copolymers were characterized by elemental analysis. The metal ion binding properties of these water-soluble polymers with Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Hg(II), Fe(III), and Cr(III) ions were investigated in aqueous solution using the Liquid-Phase Polymer-Based Retention (LPR) technique. Poly(acrylic acid-co-acrylamide) showed a higher retention compared to the homopolymers for all the metal ions except of Hg(II), which was not retained. Besides, the retention of Cd(II) is higher than that an addition of the retention of both homopolymers. It may be attributed to a synergic effect. Maximum capacity for Cu(II) at pH 5.0 was determined to be 1 mmol g−1 (63.5 mg g−1). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2461–2467, 1997