Diffusion mobility of alkali metals in perfluorinated sulfocationic and carboxylic membranes as probed by <Superscript>1</Superscript>H, <Superscript>7</Superscript>Li, <Superscript>23</Superscript>Na,and <Superscript>133</Superscript>Cs NMR spectroscopy

Water self-diffusion and ion mobilities in various ionic forms (H⁺, Li⁺, Na⁺, Rb⁺, Cs⁺, and Ba²⁺) of perfluorinated sulfocationic membranes MF-4SK were studied by NMR and impedance spectroscopy. When degrees of hydration are low, the self-diffusion coefficients of water and ionic conductivities are considerably affected by the water content of the membrane. The self-diffusion coefficients decrease in the order H⁺ > Ba²⁺ > Cs⁺ > Rb⁺ > Na⁺ > Li⁺, whereas the ion mobility decreases in the order H⁺ > Li⁺ > Na⁺ > Cs⁺ > Ba²⁺.     

Spectrophotometric studies of alkali and alkali earth metal ions complexes of mono amino derivative of calix[4]arene

The synthesis and complexive abilities of 5,11,17-tris(tert-butyl)-23 amino-25,26,27,28-tetra-propoxycalix[4]arene towards alkali cations Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺ and alkali earth cations Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ in methanol-chloroform mixture have been evaluated at 25°C, using UV-Vis spectrophotometric techniques. The results showed that the ligand is capable to complex with all the cations by 1: 1 metal to ligand ratios. The selectivity presented considering the calculated formation constants are in the order Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺ and Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ with the ligand.     

Trennungen von Kationen in Titanhexacyanoferrat(II)-S?ulen

Zusammenfassung Die Trennung der Ionenpaare Rb⁺/Cs⁺, K⁺/Rb⁺, K⁺/Cs⁺, Na⁺/K⁺, Li⁺/Na⁺ mit Salzsäure oder Ammoniumchloridlösung als Elutionsmittel gelingt quantitativ oder nahezu quantitativ mit Hilfe von Titanhexacyanoferrat(II)-säulen. Die Cäsiumionen können nicht eluiert werden. Ebenso gelingt die Trennung der lonenpaare Sr²⁺/Ba²⁺, Ca²⁺/Ba²⁺, Ba²⁺/Cs⁺ und Sr²⁺/Cs⁺ quantitativ oder nahezu quantitativ. Auch eine partielle Trennung der Seltenen Erden ist möglich; Yttrium ist leichter eluierbar als die Lanthanide.

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Summary The quantitative or nearly quantitative separation of the ion pairs Rb⁺/Cs⁺, K⁺/Rb⁺, k⁺/Cs⁺, Na⁺/K⁺ and Li⁺/Na⁺ can be achieved with hydrochloric acid or ammonium chloride solutions as eluents by means of columns of titanium hexacyanoferrate(II). The elution of the Cs⁺ ions is not possible. In the same way the quantitative or nearly quantitative separation of the ion pairs Sr²⁺/Ba²⁺, Ca²⁺/Ba²⁺, Ba²⁺/Cs⁺ and Sr²⁺/Cs⁺ can be achieved. Also a partial separation of the rare-earth elements is possible; yttrium is more easily eluted than the lanthanides.

     

Cation exchange, interlayer spacing, and thermal analysis of Na/Ca-montmorillonite modified with alkaline and alkaline earth metal ions

Na-montmorillonites were exchanged with Li⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺, while Ca-montmorillonites were treated with alkaline and alkaline earth ions except for Ra²⁺ and Ca²⁺. Montmorillonites with interlayer cations Li⁺ or Na⁺ have remarkable swelling capacity and keep excellent stability. It is shown that metal ions represent different exchange ability as follows: Cs⁺?>?Rb⁺?>?K⁺?>?Na⁺?>?Li⁺ and Ba²⁺?>?Sr²⁺?>?Ca²⁺?>?Mg²⁺. The cation exchange capacity with single ion exchange capacity illustrates that Mg²⁺ and Ca²⁺ do not only take part in cation exchange but also produce physical adsorption on the montmorillonite. Although interlayer spacing d ₀₀₁ depends on both radius and hydration radius of interlayer cations, the latter one plays a decisive role in changing d ₀₀₁ value. Three stages of temperature intervals of dehydration are observed from the TG/DSC curves: the release of surface water adsorbed (36?C84?°C), the dehydration of interlayer water and the chemical-adsorption water (47?C189?°C) and dehydration of bound water of interlayer metal cation (108?C268?°C). Data show that the quantity and hydration energy of ions adsorbed on montmorillonite influence the water content in montmorillonite. Mg²⁺-modified Na-montmorillonite which absorbs the most quantity of ions with the highest hydration energy has the maximum water content up to 8.84%.     

Application of localized reactivity index in combination with periodic DFT calculation to rationalize the swelling mechanism of clay type inorganic material

Clays are layered alumino-silicates. Clays swell and expand in aqueous solution. This property governs the usage of these materials in synthesis of nano-composites and is a source of many of its catalytic applications. We used both localized and periodic calculations within the realm of density functional theory (DFT) on a series of monovalent (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺), and divalent (Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺) cations, to monitor their effect on the swelling of clays. The activity order obtained for the exchangeable cations among all the monovalent and divalent series studied is: Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ > Cs⁺ > Rb⁺ > Na⁺ > Li⁺ > K⁺. We have studied two types of clays, montmorillonite and beidellite, with different surface structures and with/without water using periodic calculations. We have calculated the layer spacing at the first, second and third hydration shells of exchangeable cation, to compare with the experimentald-spacing values to correlate with humidity. A novel quantitative scale is proposed in terms of the intermolecular relative nucleophilicity of the active cation sites in their hydrated state through Fukui functions using hard-soft acid base (HSAB) principle. Finally, a swelling mechanism is proposed. This is a unique study where a combination of periodic and localized calculations has been performed to validate the capability of reactivity index calculations in material designing.     

Die Selektivität Kristalliner Cer(IV)-Phosphatsulfathydrate gegenüber Li+, Na+, K+, Rb+, Cs+ und NH in absolutem Methanol und absolutem Dimethylsulfoxid

Selectivity of Crystalline Ce^IV Phosphate Sulphate Hydrates for Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and NH in Absolute Methanol and Absolute Dimethylsulphoxide The sequence of exchange capacities of Cerium(IV) phosphate sulphate hydrate (CePO₄)₂(HPO₄)_0.74(SO₄)_0.26 · 4,74 H₂O for alkalimetal ions and ammoniumions in absolute methanol at 25°C for the case of a small excess of the exchanger (in relation to the equivalent amount) is given by K⁺ > Rb⁺ ≥ NH₄⁺ > Cs⁺ > Na⁺ > Li⁺. Between the exchange capacity A of these cations and their ionic radii r (given by Ladd) exists the simple relation A = const./r. For Na⁺ the radius of the inner hydration shell must be considered. In absolute dimethyl-sulphoxide under the same conditions the sequence is K⁺ ≥ NH₄ > Rb⁺ > Na⁺ > Cs⁺ > Li⁺. For K⁺, NH₄, Rb⁺ and Cs⁺ the exchange capacity is given by A = const./r + const. · r⁴. The sequences of the alkali ions in both solvents are among the group of 13 sequences which are physicaly significant according to EISENMANNS 's theory. The results are compared with the observations made with water as solvent.     

Selective complexation of alkali metal ions and nanotubular cyclopeptides: a DFT study

A density functional theory based on interaction of alkali metal cations (Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺) with cyclic peptides constructed from 3 or 4 alanine molecule (CyAla3 and CyAla4), has been investigated using mixed basis set (C, H, O, Li⁺, Na⁺ and K⁺ using 6-31+G(d), and the heavier cations: Rb⁺ and Cs⁺ using LANL2DZ). The minimum energy structures, binding energies, and various thermodynamic parameters of free ligands and their metal cations complexes have been determined with B3LYP and CAM-B3LYP functionals. The order of interaction energies were found to be Li⁺ > K⁺ > Na⁺ > Rb⁺ > Cs⁺ and Li⁺ > Na⁺ > K⁺ ? Rb⁺ > Cs⁺, calculated at CAM-B3LYP level for the M/CyAla3 and M/CyAla4 complexes, respectively. Their selectivity trend shows that the highest cation selectivity for Li⁺ over other alkali metal ions has been achieved on the basis of thermodynamic analysis. The main types of driving force host–guest interactions are investigated, the electron-donating O offers lone pair electrons to the contacting LP* of alkali metal cations.     

Explanation of Ionic Sequences in Various Phenomena. I. Salting-Out of Uncharged Molecules

Abstract

Theoretical models for hydrated ions and their calculated effective dielectric constants obtained previously were used to explain the salting-in or salting-out of nonionic molecules. Three types of salting-out sequences were obtained: nonpolar (Na⁺ > K⁺ > Li⁺ Rb⁺ > Cs⁺), basic (K⁺ > Na⁺ > Rb⁺ > Cs⁺ > Li⁺), and acidic (Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺). The nonpolar sequence is not influenced by the A region of a cation, and therefore the ability to salt-out is great if the effective dielectric constant of the ion is small. The A region on hydrated Li⁺ ions (the tightly bound water) salts-in basic compounds because of the interaction of its positively charged hydrogen atoms with the negative dipolar charge of the base. Conversely, the A region of a cation salts-out acidic compounds because the hydroxyl group on carboxylic acids behaves as a similar cationic A region. A sulfonic polymer will cause the salting-in of the base p-nitroaniline because the addition of salts to an aqueous solution of the base and polymer destroys hydrogen bonds in the polymer and in so doing releases hydronium ions from the polymer. This release of H⁺, in turn, produces a positive charge on part of the p-nitroaniline molecules, which produces a salting-in effect.     

The electrical conductivity of a network polymer based on tetraphenylcalix[4]resorcinarene

The electrical conductivity of a polymer based on tetraphenylcalix[4]resorcinarene in the form of H⁺, Na⁺, Li⁺, Ag⁺, and Ba²⁺ cations was measured, and the self-diffusion coefficients and activation energies of metal cation diffusion in the polymer phase were calculated. It was found that the specific conductivity of the polymer in the form of Ba²⁺ cations was 0.004 S/cm, increased to 0.01 S/cm when the polymer was in the form of singly-charged metal cations, and became as high as 0.2 S/cm when the polymer was transformed into the H form. It was shown that the self-diffusion coefficients of metal cations in the polymer phase increased in the sequence Ba²⁺ < Ag⁺, Li⁺ < Na⁺. The conclusion was made that, over the temperature range 298–333 K, the activation energy of metal cation diffusion in polymer was 14–15 kJ/mol and did not obviously depend on the cation charge. Original Russian Text ? G.N. Al’tshuler, E.V. Ostapova, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 6, pp. 1171–1174.     

Activity of Palladium Catalysts Based on FIBAN K-1 Fibrous Sulfonic Cation Exchanger in Reaction of Hydrogen Oxidation

For palladium catalysts based on FIBAN K-1 fibrous sulfonic cation exchanger (Li⁺, Na⁺, Rb⁺, Cs⁺,Mg²⁺,Ca²⁺, Ba²⁺ forms) the dispersity and depth distribution of palladium metal in the fiber and the activity of the catalyst in hydrogen oxidation were studied in relation to the conditions of the synthesis and activation.     

Selectivity ratios of cation-sensitive glass electrodes in ethanol-water mixtures

Summary The response of cation-sensitive glass electrodes to univalent cations in ethanol-water mixtures shows increasing e.m.f. values with increasing fractions of ethanol for Na⁺, K⁺, Cs⁺, Rb⁺, Li⁺, and NH₄ ⁺, but anomalous behavior for H⁺. The calculated selectivity of the glass electrode for metal ions over the hydrogen ion thus increases sharply over the range of 10–70 weight % ethanol. It is suggested that sodium rather than hydrogen ion may be adopted as the reference ion for the definition of selectivity ratios in mixed solvents.

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Zusammenfassung Die Ansprechbarkeit von kation-empfindlichen Glaselektroden auf einwertige Kationen (Na⁺, K⁺, Cs⁺, Rb⁺, Li⁺, NH₄ ⁺) in Äthanol-Wassergemischen weist mit steigendem Äthanolgehalt steigende E.M.K.-Werte auf; H⁺ zeigt ein abweichendes Verhalten. Die berechnete SelektivitÄt der Glaselektrode für Metallionen nimmt daher im Bereich von 10–70% Äthanol stark zu. Es wird empfohlen, für die Definition von SelektivitÄtsverhÄltnissen in Lösungsmittelgemischen Na⁺ an Stelle von H⁺ als Bezugsion zu verwenden.

     

A new Na+ and K+ carrier from chemically modified monensin studied in human erythrocytes by 23Na nuclear magnetic resonance,K+ atomic absorption and H+ potentiometry

The transporting ability of a new monensin derivative 26-(1,2-diphenyl-1-ethoxy) monensin, highly active against Gram-positive bacteria, was explored with the human erythrocyte model using three technical approaches: ²³Na nuclear magnetic resonance (internal Na⁺), K⁺ atomic absorption (external K⁺) and H⁺ potentiometry (external H⁺) and compared with monensin 1 and 26-(4-chlorophenylurethane) monensin 3 of known transport selectivities for sodium and potassium respectively. Compound 2 proved to be a good carrier for both Na⁺ and K⁺ under our experimental conditions, thus constituting a new type of monensin derivative. The introduction of Li⁺, Rb⁺ or Cs⁺ in the external buffer as a replacement for Na⁺ led us to propose the transport sequence K⁺, Na⁺ ⪢ Rb⁺ > Li⁺ > Cs⁺ for 2.     

Alkalikationen-Spezifität und Träger-Eigenschaften der Antibiotica Nigericin und Monensin

It is shown by means of IR. spectroscopic methods that nigericin and monensin have a cyclic conformation similar to that of their silver salts. Complex formation constants with sodium and potassium ions follow the selectivity order determined by EMF. measurements on liquid membranes: nigericin: K⁺ > Rb⁺ > Na⁺ > Cs⁺ > Li⁺; monensin: Na⁺ > K⁺ > Li⁺ > Rb⁺ > Cs⁺. Transport experiments show that nigericin and monensin facilitate the diffusion of potassiumions across model membranes, although in electrolytic transport experiments the permeability is not affected.     

Counterion binding by poly(styrenesulfonate)

Binding isotherms of poly(styrenesulfonate) with hydrogen and selected alkali ions have been determined by dialysis equilibrium and dye spectroscopy, employing Pb²⁺, Mg²⁺, and Ca²⁺ as the competing divalent ions. The observed degrees of counterion binding, Θ_z, defined as the number of bound counterfoils of valence z per poly ion site-group, agree quite well with those predicted by Manning's two variable theory. The binding preference follows the order Cs⁺ > Rb⁺ > K⁺ > Na⁺ > H⁺ >Li⁺, indicating that the binding process is of a territorial nature. Independently performed light scattering measurements show that a plot of the radius of gyration, >S _z>, against the actual polyion charge gives a sigmoidal curve. This result is taken to indicate that (1) a polyion is, in general, not completely neutralized in the Θ-state and that (2) a polyion may be not fully stretched when the polyion charge density is largest.     

Fluoride complexes of the alkali metal ions

Measurements by fluoride ion-selective electrode potentiometry on the very weak monofluoride complexes of the alkali metal ions in aqueous solution at 25°C and an ionic strength of 1M indicate their stability constants lie in the order Li⁺ > Na⁺ > K⁺ > Rb⁺ ? Cs⁺. Data at varying ionic strengths and temperatures were used to calculate infinite dilution stability constants and enthalpies and entropies of complexation for LiF and NaF.     

Polarographie in 1,2-propandiolcarbonat, 1. Mitt.: Ionen der alkali- und erdalkalimetalle

Zusammenfassung Die Ionen der Alkali- und Erdalkalimetalle sowie von Ammonium wurden in 1,2-Propandiolcarbonat polarographisch untersucht; die Art der Grenzströme, die Diffusionsstromkonstanten, die Diffusionskoeffizienten, die Art der Abscheidungsvorgänge und die Halbwellenpotentiale gegen die gesättigte wäßrige Kalomelelektrode wurden bei 25,0^o in 0,1m-Lösungen von Tetraäthylammoniumperchlorat in 1,2-Propandiolcarbonat bestimmt. Alle untersuchten Ionen geben je eine klare Reduktionswelle mit diffusionsbedingtem Grenzstrom, wobei die Elektrodenreaktion an der tropfenden Quecksilberelektrode für Na⁺, K⁺, NH₄ ⁺, Rb⁺, Cs⁺, Sr²⁺ und Ba²⁺ reversibel, für Li⁺, Be²⁺, Mg²⁺ und Ca²⁺ irreversibel abläuft. Analytische Simultanbestimmungen von Natrium und Kalium bzw. Calcium, Strontium und Barium sind auf Grund der Lage der Halbwellenpotentiale möglich. Der Einfluß von Wasser ist bis zu 1% unmerklich.

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Polarographic investigations were carried out on alkali and alkaline earth metal ions, and on the ammonium ion, in propanediol-1,2-carbonate; the nature of the limiting currents, the diffusion current constants, the diffusion coefficients, the reversibility or irreversibility, and the half-wave potentials vs. aqueous saturated calomel electrode, were determined in 0,1m-solutions of tetraethylammonium perchlorate at 25.0^o. Each of the ions investigated exhibits a well defined reduction wave with diffusion-controlled limiting current; the electrode reactions are reversible for Na⁺, K⁺, NH₄ ⁺, Rb⁺, Cs⁺, Sr²⁺, and Ba²⁺, and irreversible for Li⁺, Be²⁺, Mg²⁺, and Ca²⁺. The simultaneous analytical determination of sodium and potassium as well as of calcium, strontium, and barium is possible. The influence of water up to 1% is neglegibly small.

     

Factors Influence Complexing Selectivity of Lariat Crown Ethers Toward Alkali Metal Ions in Electrospray Ionization Mass Spectrometry

The selectivity of eight lariat crown ethers in the sym‐dibenzo‐16‐crown‐5 series toward alkali metal ions was studied with electrospray ionization mass spectrometry under different conditions. With the exception of 2g , which is equally selective toward Na⁺ and Li⁺, all other lariat crown ethers show the best selectivity toward Li⁺ in methanol. Factors that influence the selectivity include the water content, counterions, nature of the side arms, and the externally added cations. Iodide gives the best Na⁺ selectivity with R_I > R_Br > R_Cl. Increased water content profoundly increases the Na⁺ selectivity when the side arm is hydrophilic and the steric hindrance is small. Externally added cations (Cs⁺ and/or Rb⁺) enhance the Na⁺ selectivity by exchanging the smaller Li⁺ from the cavity.     

A DFT/PCM Study on the Affinity of Salinomycin to Bind Monovalent Metal Cations

The affinity of the polyether ionophore salinomycin to bind IA/IB metal ions was accessed using the Gibbs free energy of the competition reaction between SalNa (taken as a reference) and its rival ions: [M⁺-solution] + [SalNa] → [SalM] + [Na⁺-solution] (M = Li, K, Rb, Cs, Cu, Ag, Au). The DFT/PCM computations revealed that the ionic radius, charge density and accepting ability of the competing metal cations, as well as the dielectric properties of the solvent, have an influence upon the selectivity of salinomycin. The optimized structures of the monovalent metal complexes demonstrate the flexibility of the ionophore, allowing the coordination of one or two water ligands in SalM-W₁ and SalM-W₂, respectively. The metal cations are responsible for the inner coordination sphere geometry, with coordination numbers spread between 2 (Au⁺), 4 (Li⁺ and Cu⁺), 5/6 (Na⁺, K⁺, Ag⁺), 6/7 (Rb⁺) and 7/8 (Cs⁺). The metals’ affinity to salinomycin in low-polarity media follows the order of Li⁺ > Cu⁺ > Na⁺ > K⁺ > Au⁺ > Ag⁺ > Rb⁺ > Cs⁺, whereas some derangement takes place in high-dielectric environment: Li⁺ ≥ Na⁺ > K⁺ > Cu⁺ > Au⁺ > Ag⁺ > Rb⁺ > Cs⁺.     

Contribution to the thermodynamics of complexes of alkali metal cations with 18-crown-6 in the water—nitrobenzene extraction system

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq)+NaL⁺(nb)⇄ML⁺(nb)+Na⁺(aq) taking place in the two-phase water-nitrobenzene system (M⁺=Li⁺, K⁺, Rb⁺, Cs⁺; L=18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. The stability constants of the ML⁺ complexes in nitrobenzene saturated with water were calculated; they are found to increase in the cation order Cs⁺Li⁺Na⁺Rb⁺K⁺. Further, the individual extraction constants for the NaL⁺, KL⁺, RbL⁺ and CsL⁺ complex species in the wate-nitrobenzene system were determined; their values increase in the series Na⁺Rb⁺Cs⁺K⁺.     

Preparation of Thallium Hexacyanoferrate Film and Mixed‐Film Modified Electrodes with Cobalt(II) Hexacyanoferrate

Thallium hexacyanoferrate films have been prepared from various aqueous electrolyte solutions using consecutive cyclic voltammetry. The cyclic voltammograms recorded the direct deposition of thallium hexacyanoferrate films from the mixing of Tl³⁺ and [Fe(CN)₆]^3? ions from solutions of seven cations: Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, H⁺, and Tl⁺. An electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the thallium hexacyanoferrate films. The thallium hexacyanoferrate film shows a single redox couple with a formal potential between +0.6 V and +1.2 V, and shows a cation effect (H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and Tl⁺). A mixed film and a two‐layered modified electrodes composed of a thallium hexacyanoferrate film with cobalt(II) hexacyanoferrate film were prepared.