Cation binding by 2<Superscript>1</Superscript>,3<Superscript>1</Superscript>-diphenyl-l <Superscript>2</Superscript>,4<Superscript>2</Superscript>-dioxo-7,10,13-trioxa-1,4(3,1)-diquinoxalina-2 (2,3),3(3,2)-diindolizinacyclopentadecaphane and its acyclic analog

The binding of cations Li⁺, Na⁺, K⁺, Cs⁺, Ag⁺, Zn²⁺, Ni²⁺, Co²⁺, NH₄ ⁺ (group I), H⁺, Mg²⁺, Al³⁺, Ga³⁺ (group II), and Ca²⁺, Pb²⁺ (group III) by 2¹,3¹-diphenyl-l ²,4²-dioxo- 7,10,13-trioxa-l,4(3,1)-diquinoxalina-2(2,3),3(3,2)-diindolizinacyclopentadecaphane (1), which contains two indolizine and two quinoxaline fragments and 3,6,9-trioxaundecanes spacer, and by its acyclic analog (2) was studied using cyclic voltammetry in MeCN/0.1 M Bu₄NBF₄. It was concluded that the ions of group I are not bound by these compounds, the ions of group II exhibit the reversible redox-switched binding by the carbamoyl groups of the quinoxaline fragments, whereas the ions of group III are bound not only by the initial compounds and radical cations 1 and 2, but also by dication 1. This binding of the Ca²⁺ and Pb²⁺ ions stabilizes dication 1.     

Redox-switchable binding of the Mg2+ ions by 21,31-diphenyl-12,42-dioxo-7,10,13-trioxa-1,4(3,1)-diquinoxaline-2(2,3),3(3,2)-diindolysine-cyclopentadecaphane

The binding of the Li⁺, Na⁺, K⁺, Mg²⁺, and Co²⁺ ions by 2¹,3¹-diphenyl-1²,4²-dioxo-7,10,13-trioxa-1,4(3,1)-diquinoxaline-2(2,3),3(3,2)-diindolysine-cyclopentadecaphane containing two indolysine fragments, two quinoxaline fragments, and 3,6,9-trioxyundecane spacer in the acetonitrile/0.1 M Bu₄NBF₄ environment is studied by the method of cyclic voltammetry. It is demonstrated that the Li⁺, Na⁺, K⁺, and Co²⁺ ions are not bound by this macrocycle, whereas selective redox-switchable binding is observed for the Mg²⁺ ions. The macrocycle binds the Mg²⁺ ions way more efficiently as compared with its radical cation and dication. The indolysinequinoxaline fragments play the determining role in the binding. Original Russian Text ? V.V. Yanilkin, N.V. Nastapova, V.A. Mamedov, A.A. Kalinin, V.P. Gubskaya, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 808–814.     

Synthesis and extraction properties of oxathiacrown compounds containing benzyl groups

8-Benzyl-1.4-dioxa-7,10-dithiacyclododecane and 11-benzyl-1,4,7-trioxa-10,13-dithiacyclopentadecane were obtained by the interaction of (2,3-dibromo-1-propyl)benzene with 1,8-dimercapto-3,6-dioxaoctane and 1,11-dimercapto-3,6,9-trioxaundecane. The extracting ability of the obtained compounds has been studied in relation to Sr²⁺ and Pb²⁺ ions from aqueous solutions in the presence of anions of various degrees of hardness with determination of the metal content by a radiometric method. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 244–249, February, 2006.     

A luminescence probe for measurements of electron-exchange rates in polymer films on electrodes

The effect of metal ions on the, reduction of 1,10-phenanthroline-5,6-quinone (1), 5,8-quinolinequinone (II) and 6,7-dichloro-5, 8-quinolinequinone (III) has been investigated in 50% dimethylsulfoxide+water solvent. 1 contains the 1,10-phenanthroline structure in both its quinone and hydroquinone forms, while II and III contain the 8-hydroxyquinoline structure in the hydroquinone forms. Complexation of the hydroquinones of II and III by metal ions causes positive shifts in the quinone half-wave potentials. These shifts have been used to calculate conditional formation constants for Pb²⁺(II) and Pb²⁺ and Zn²⁺(III). The quinone form of I binds strongly to Ni²⁺, Co²⁺ and Zn²⁺ but not to Ca²⁺. Mg²⁺. Mg₂₊. Mn²⁺ and Pb²⁺. With the latter four metals, binding to the hydroquinone from of I was detected and formation constants were determined. In addition to binding both the quinone and hydroquinone forms at the nitrogen atoms, Ni₂₊ Co²⁺ and Zn²⁺ formed complexes at the 1,2-dihydroxy site of the hydroquinone of I.     

Complex formation between azacrown derivatives of dibenzylidenecyclopentanone and alkali-earth metal ions

The complex formation of 2,5-bis[4-(1,7,10,13-tetraoxa-4-azacyclopentadec-4-yl)benzylidene]cyclopentanone and several model compounds, prospective metal-sensitive fluorescent probes, with Mg²⁺, Ca²⁺, and Ba²⁺ ions in acetonitrile was studied. The azacrown derivatives of dibenzylidenecyclopentanone have two complex formation centers, azacrown cycle and carbonyl group. The sequence of binding to these sites is different for different ions. The efficient ejection of the Ca²⁺ and Ba²⁺ ions from their complexes with azacoronands was observed in the excited state, whereas in the case of the Mg²⁺ ion, this process occurred only partially.     

Metal Ion Interaction of Two New Tritopic N2O13 Macrobicycles with B15C5 Moieties in Acetonitrile Solution

The synthesis of two new tritopic crown ligands (L1 and L2) bearing two benzo-15-crown-5 lateral moieties linked through a dibenzo-trioxa chain together with their interaction with metal ions, in acetonitrile and acetonitrile–water (50%, v/v) solutions is reported. The influence of K⁺, Na⁺, Li⁺, Ca²⁺, Ba²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺ and Al³⁺, on the spectroscopic properties of these diaza-polyoxa ligands was investigated by absorption spectrophotometry and in some cases by fluorescence emission spectroscopy. Coordination with alkaline (Na⁺, K⁺ and Li⁺) and alkaline earth (Ca²⁺and Ba²⁺) metal ions is assumed to be weak with both macrobicyclic ligands, while the interaction with both imine and amine derivatives causes a minor effect in the absorption spectra. Coordination with Cu²⁺, Zn²⁺ and Pb²⁺ in acetonitrile solution causes a major change in the absorption spectra of the chromophores. In the case of Cu²⁺, addition of the metal to L1 or L2 leads to a blue–violet complex in solution with an absorbance maximum centred at 590 nm. Interaction of the Schiff-base L1 with Pb²⁺ leads to a short wavelength shift in the absorption bands, comparable with the ZnL1 complex. Presence of transition metal ions such as Co²⁺, Ni²⁺and Cd²⁺ do not remarkably affect the absorption spectra of L1 and L2 in solution. Trivalent aluminium has a modest effect in the absorption bands of both N₂O₁₃ donor set bismacrocyclic ligands. The fluorescence study of L2 in the presence of Na⁺, K⁺, Ca²⁺, Ba²⁺, Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Al³⁺shows that Cu²⁺, Pb²⁺ and Al³⁺ complexes form non-fluorescent complexes.     

A new chelating resin containing 2-aminothiophenol: Synthesis characterization and determination of mercury in waste water using <Superscript>203</Superscript>Hg radiotracer

A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg²⁺ as a function of pH has been studied using ²⁰³Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of mercury(II) in presence of different alkali and alkaline earth metal ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺), common anions (ClO₄ ⁻, SO₄ ²⁻) and other diverse ions (Ag⁺, Cu²⁺, Pb²⁺, Fe³⁺, Ni²⁺ and Zn²⁺) has been checked. In column operation it has been observed that Hg²⁺ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method and the concentration of Hg²⁺ in the waste water spiked with ²⁰³Hg was found to be 0.05 to 0.09 μg/ml.     

Chemical properties of N-2-Sulfoethylchitosan with a medium degree of substitution

A method was developed for the preparation of N-2-sulfoethylchitosan (SECH) via synthesis in a gel with the use of the reaction of chitosan and sodium 2-bromoethanesulfonate. This method makes it possible to conduct a polymer-like transformation without any acid or base. The structures of the obtained polymers were confirmed via IR and ¹H NMR spectroscopy. The study of the sorption of Ag⁺, Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Pb²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ ions that were crosslinked by SECH during their joint presence in an ammonia-acetate buffer solution showed high values of selectivity in relation to those of silver(I) and copper(II). The selectivity of the sorption of silver(I) ions with respect to copper(II) ions increased with an increase in the degree of substitution of SECH.     

The use of ESI-MS to probe the binding of divalent cations to calmodulin

Proteins have evolved with distinct sites for binding particular metal ions. This allows metalloproteins to perform a myriad of specialized tasks with conformations tailor-made by the combination of its primary sequence and the effect on this of the ligated metal ion. Here we investigate the selectivity of the calcium trigger protein calmodulin for divalent metal ions. This ubiquitous and highly abundant protein exists in equilibrium between its apo and its holo form wherein four calcium ions are bound. Amongst its many functions, calmodulin modulates the calcium concentration present in cells, but this functional property renders it a target for competition from other metal ions. We study the competition posed by four other divalent cations for the calcium binding sites in calmodulin using electrospray ionization mass spectrometry (ESI-MS). We have chosen two other group II cations Mg²⁺, Sr²⁺, and two heavy metals Cd²⁺, Pb²⁺. The ease with which each of these metals binds to apo and to holo CaM[4Ca] is described. We find that each metal ion has different properties with respect to calmodulin binding and competition with calcium. The order of affinity for apo CaM is Ca²⁺ ≫ Sr²⁺ ∼ Mg²⁺ > Pb²⁺ ∼ Cd²⁺. In the presence of calcium the affinity alters to Pb²⁺ > Ca²⁺ > Cd²⁺ > Sr²⁺ > Mg²⁺. Once complexes have been formed between the metal ions and protein (CaM:[xM]) we investigate whether the structural change which must accompanies calcium ligation to allow target binding takes place for a given CaM:[xM] system. We use a 20 residue target peptide, which forms the CaM binding site within the enzyme neuronal nitric-oxide synthase. Our earlier work (Shirran et al. 2005) [1] has demonstrated the particular selectivity of this system for CaM:4Ca²⁺. We find that along with Ca²⁺ only Pb²⁺ forms complexes of the form CaM:4M²⁺:nNOS. This work demonstrates the affinity for calcium above all other metals, but also warns about the ability of lead to replace calcium with apparent ease.     

A New Fluorescent Chemosensor for Metal Ions Based upon 1,8‐Naphthalimide and 8‐Hydroxyquinoline

A new fluorescent chemosensor based upon 1,8‐naphthalimide and 8‐hydroxyquinoline was synthesized, and its fluorescent properties in the presence of different metal cations (Hg²⁺, Ag⁺, Zn²⁺, Fe²⁺, Cd²⁺, Pb²⁺, Ca²⁺, Cu²⁺, Mg²⁺, and Ba²⁺) were investigated. It displayed fluorescence quenching with some heavy and transition metal (HTM) ions, and the quenching strongly depended on the nature of HTM ions.     

Studies on the effects of doping cesium metal(III) halides of the type Cs3MIII2X9 (MIII = Sb or Bi, X = Cl or Br)

A series of compounds, Cs₃M^III₂X₉ (M^III = Sb and Bi, X = Cl or Br) are doped with impurity ions (Ba²⁺, Ca²⁺, Sn²⁺, Pb²⁺, Mg²⁺, Fe²⁺, Tl³⁺, In³⁺, Se⁴⁺). Lattices doped with Sn(II), Pb(II) and Se(IV) are colored. Sn-119m Mössbauer data are consistent with the donation of Sn-5s electron density from tin(II) to a conduction band to give a pseudo-tin(IV) electronic environment.     

Synthesis of lariat organochalcogenoethers based on azacalix[3]arenes for the potentiometric detection of [UO2] ions

The syntheses of organochalcogen-supported azacalix[3]arenes are described in a one-pot manner in satisfactory yields. A remarkably selective potentiometric response was accomplished for uranyl ions over a variety of other metal ions, including alkali (Na⁺, K⁺), alkaline-earth (Mg²⁺, Ca²⁺, Ba²⁺), transition and heavy metal ions (Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Fe³⁺, Zn²⁺, Cd²⁺ and Pb²⁺) using an ion-selective electrode based on compound 3 incorporated into a polymeric (PVC) membrane.     

Conductometric and microcalorimetric analysis of the alkaline-earth/alkali-metal ion exchange onto polyacrylic acid

The specificity of the exchange between divalent (Di²⁺ = Ca²⁺ or Ba²⁺) and monovalent (M⁺ = Li⁺, Na⁺ or K⁺) ions onto a polyacrylic chain is examined using conductometric and microcalorimetric techniques. Assuming the formation of a bidentate complex between the Di²⁺ and the carboxylate groups, the conductometric data give the exchange ratio (Di²⁺/M⁺) and the speciation of the acrylic groups. No significant difference is observed between the three alkali-metal ions for a given Di²⁺ ion. Comparisons between Ca²⁺ and Ba²⁺ show a stronger hydrophobicity of the former as it precipitates at a complexation ratio r = 0.33 versus r = 0.45 for the Ba²⁺ salt. Microcalorimetric data show that all Di²⁺/M⁺ exchange energies are positive and depend significantly on the type of cations. The largest displacement energy (the more positive) is found for the binding of Ca²⁺ with sodium polyacrylate (8.13 kJ · mol⁻¹) and the smallest for Ba²⁺ with lithium polyacrylate (1.88 kJ · mol⁻¹). The interpretation of the data leads to the conclusion that specificity of the Di²⁺ binding originates in the dehydration phenomenon and specificity between the three alkali-metal ions is due to the decrease in the electrostatic bond strength with an increase in the ionic radii. The Di²⁺/M⁺ exchange is entropically driven. Received: 28 January 1999 Accepted in revised form: 7 April 1999     

Study on the synthesis of novel fluorescent macrocyclic sensors and their sensitive properties for Cu2+ and Fe3+ in aqueous solution

In this work, we synthesised and characterised three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesised compounds with various mental ions (Li⁺, Na⁺, K⁺, Ag⁺, Mg²⁺, Ca²⁺, Ba²⁺, Pb²⁺, Zn²⁺, Co²⁺, Cd²⁺, Hg²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Cr³⁺, Al³⁺, Fe³⁺) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu²⁺ and Fe³⁺ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H₂O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated.     

Complexation Properties of a Carbon-Bridged Cryptand with Metal Ions in Aqueous Solution at 25°C

Abstract

Thermodynamic quantities (log K, ΔH, and ΔS) for the interactions of a carbon-bridged cryptand with Li⁺, Na⁺, K⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺ were determined at 25° C by calorimetric titration in aqueous solution. The cryptand forms complexes with Na⁺, Sr²⁺, Ba²⁺, and Pb²⁺ with log K ≤ 2. Complexation was not detected for Li⁺, K⁺, and Ca²⁺. Weak interactions with Li⁺ and K⁺ and a log K value of 2.4 for Na⁺ suggest that the cavity size of the cryptand is close to that of Na⁺ but too small for K⁺ and too large for Li⁺. The carbon-bridged cryptand selectively binds Sr²⁺ (log K = 3.2) over Ca²⁺ and Ba²⁺ by more than one order of magnitude.     

A Highly Copper‐Selective Ratiometric Fluorescent Sensor Based on BODIPY

A new ratiometric fluorescent sensor ( 1 ) for Cu²⁺ based on 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) with di(2‐picolyl)amine (DPA) as ion recognition subunit has been synthesized and investigated in this work. The binding abilities of 1 towards different metal ions such as alkali and alkaline earth metal ions (Na⁺, K⁺, Mg²⁺, Ca²⁺) and other metal ions ( Ba²⁺, Zn²⁺, Cd²⁺, Fe²⁺, Fe³⁺, Pb²⁺, Ni²⁺, Co²⁺, Hg²⁺, Ag⁺) have been examined by UV‐vis and fluorescence spectroscopies. 1 displays high selectivity for Cu²⁺ among all test metal ions and a ～10‐fold fluorescence enhancement in I₅₈₂/I₅₅₈ upon excitation at visible excitation wavelength. The binding mode of 1 and Cu²⁺ is a 1:1 stoichiometry determined via studies of Job plot, the nonlinear fitting of the fluorometric titration and ESI mass.     

Highly selective colorimetric naked-eye Cu2+ detection using new bispyrazolone silver nanoparticle-based chemosensor

In this work, we have successfully developed novel silver nanoconjugates of pyrazolone analogue and screened its chemosensing potential in aqueous medium. Bispyrazolone silver nanoparticles (Bispyra-AgNPs) were synthesised and characterised through FTIR, UV-visible spectroscopy and atomic force microscopy. The sensing ability was explored towards Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Li⁺, Pb²⁺, La³⁺, Hg²⁺, Mg²⁺, Ni²⁺ and Ba²⁺ metal ions, respectively. Bispyra-AgNPs showed a highly quenching potential in selective recognition of Cu²⁺and colour of the solution immediately turned from yellow to purple, after the addition of Cu²⁺ in to the solution. The developed method also displayed a remarkable selectivity for Cu²⁺ over others interfering metal ions. The binding ratio and stoichiometry of host-guest complex was found to be 1:1 and determined by Job’s method. The propose method is facile and sensitive to detect Cu²⁺ with detection limit of 10 µM.     

The application of ion-exchanger foils in the determination of trace amounts of some metals in water by means of the non-dispersive X-ray fluorescence method

Preliminary enrichment by means of strong acid ion-exchanger foils has been used to determine trace amounts of metals in water. The kinetics of the exchange reaction between the hydrogen ions in the cation-exchanger foil and metal ions in the solution has been studied. The time needed for the attainment of equilibrium and the values of the distribution coefficients have been determined for Fe²⁺, Zn²⁺, Pb²⁺, Ca²⁺, Cd²⁺ and Ba²⁺ ions. The metal contents in the cation-exchanger foil were determined by means of non-dispersive X-ray fluorescence. The feasibility of the method was determined on the examples of Pb, Zn and Cd ions. The method permits trace amounts of these elements to be determined above 0.01 ppm in the solution. No significant matrix effect due to the presence of Ca and Ba was found for concentration in the solution below 60 ppm.     

Cation Complexation Properties of Hexakis(2-O-methyl-3,6-anhydro)-α-cyclodextrin: A 1H NMR Study

Abstract

The affinity of hexakis(2-O-methyl-3,6-anhydro)-α-cyclodextrin (3,6-α-CDM) for Ba²⁺, Pb²⁺, Ca²⁺ and Sr²⁺ has been tested by ¹H NMR. It was shown that 3,6-α-CDM forms strong complexes in water with Pb²⁺ and Ba²⁺. The comparison with the parent hexakis(3,6-anhydro)-α-cyclodextrin bearing hydroxyl groups instead of methoxy groups reveals that the O-CH₃ substitution significantly improves the anhydro-cyclodextrin selectivity.     

Bisnitronyl nitroxides bridged by tetra(ethyleneoxy) sensing metal ions spectroscopically and electrochemically

Compound 1 containing two nitronyl nitroxide units bridged by tetra(ethyleneoxy) was designed and synthesized for sensing metal ions, by taking the features of nitronyl nitroxides: a chromophore showing absorption in visible range, reversible oxidation/reduction and coordination to metal ions. The absorption spectrum of 1 was altered markedly upon mixing with a few rare earth metal ions and some transition metal ions. Moreover, the oxidation potential of 1 was shifted to more positive range in the presence of metal ions including Pb²⁺, Ba²⁺, and Ca²⁺. Thus, compound 1 can sense metal ions both spectroscopically and electrochemically.