Calix[4]resorcinarene Ionophore in the Ion-Selective Electrodes with Plasticized Poly(vinylchloride) Membranes

Synthetic ionophore calix[4]resorcinarene was incorporated into the poly(vinyl chloride) (PVC) plasticized membrane of an ion-selective electrode (ISE). Calixarene interactions with quaternary ammonium and alkaline metals cations in the organic and water-organic media were carefully investigated by various authors. We studied the effects of choline and Na⁺ cations present in the working solution on the ionophore which was incorporated into a membrane phase. Due to the pH sensitivity of the ionophore, a study was undertaken in a wide range of pH values. The different characteristics of calix[4]resorcinarene interactions with these cations were discovered by the ISE with the PVC plasticized membrane containing this ionophore, which respond to both the choline and Na⁺ cations due to the variation of working solution pH.     

Preparation, characterization and electrochemical corrosion studies on environmentally friendly waterborne polyurethane/Na-MMT clay nanocomposite coatings

In this study, we present the first practical evaluation for the corrosion protection effect of waterborne polyurethane (WPU)/Na⁺-montmorillonite (Na⁺-MMT) clay nanocomposite coating. Typically, a series of waterborne polyurethane (WPU)/Na⁺-montmorillonite (Na⁺-MMT) clay nanocomposite materials have been successfully prepared by effectively dispersing the inorganic nanolayers of commercially purified Na⁺-MMT clay in WPU matrix through direct aqueous solution dispersion technique. First of all, WPU was prepared by polymerizing PCL, DMPA and H₁₂MDI, followed by characterized by nuclear magnetic resonance (¹H NMR), Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). Subsequently, the as-prepared PU/Na⁺-MMT clay nanocomposite (Na⁺-PCN) materials were subsequently characterized by FTIR, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM).PCN materials in the form of coating at low Na⁺-MMT clay loading up to 3 wt% coated on the cold-rolled steel (CRS) coupons were found to exhibit superior corrosion protection effect over those of neat WPU based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance in 5 wt% aqueous NaCl electrolyte. Effects of the material composition on the gas permeability, thermal stability and optical clarity of neat WPU along with a series of Na⁺-PCN materials, in the form of coating and free-standing film, were also studies by gas permeability analyzer (GPA), thermogravimetric (TGA), differential scanning calorimetry (DSC) and ultraviolet UV-visible transmission spectroscopy, respectively. As control experiments, a series of PU/organo-MMT nanocomposite (denoted by organo-PCN) materials were also prepared for comparative studies.     

Effect of cation on the performance of AC/graphite capacitor

The effect of cation on the performance of activated carbon (AC)/graphite capacitor has been studied. Electrolytes using Li⁺ and four kinds of quaternary alkyl ammonium cations have been picked up for this investigation. The relationship between the ionic radii of cations and the specific capacitance of AC negative electrode in corresponding electrolytes has been correlated. The state of Li⁺ dissolved in PC (propylene carbonate) solvent has also been clarified.     

Alteration of biotite by suspended montmorillonite

Summary Alteration of biotite flakes which were placed in suspensions of Na⁺ — and Mg⁺⁺-montmorillonite for different contact periods at two different temperatures, were followed using X-ray and petrographic microscope.The biotite seemed to alter to a mineral of the vermiculite type. Na⁺-montmorillonite changed the biotite more than Mg⁺⁺-montmorillonite at 21°C. At 50°C, however, no changes of the biotite flakes could be observed using Na⁺-montmorillonite in contrast to the case when Mg⁺⁺-montmorillonite was used. A good correlation between X-ray measurements and optical observations was found.With 3 figures and 3 tables     

Modification of Na+-montmorillonite with mono- and bis(polyfluoroalkyl) phthalates

Layered natural aluminosilicate, Na⁺-montmorillonite, was modified with mono- and bis(polyfluoroalkyl) phthalates. The polyfluorinated esters as Na⁺-montmorillonite modifiers exhibit high organophilizing and hydrophobizing activity, as demonstrated by thermal analysis and IR spectroscopy. A change in the interlayer spacing in the clay was determined by X-ray diffraction. The capability of the modifier for intercalation into the layered structure of the clay depends on the degree of telomerization of the perfluoroalkyl residue.     

Organophilization of Na+-montmorillonite with polyfluorinated alcohols

Modification of Na⁺-montmorillonite with polyfluorinated alcohols was performed. The structure of the modified Na⁺-montmorillonite was studied by derivatography and Fourier IR spectroscopy. The effect of calcite as clay component on the capability for physical and chemical binding of polyfluorinated alcohols was revealed.     

Unusual complex between 18-Crown-6 and tetramethylammonium cation—detection by electrospray ionization mass spectrometry

Complexes between crown ethers and quaternary ammonium cations have been studied by electrospray ionisation mass spectrometry (ESI-MS). The ESI-MS method has been shown to allow observation of not only stable inclusion complexes between large crown ethers and tetramethylammonium cation (e.g. [DB30C10 + (CH₃)₄N]⁺ ion) but also of unstable inclusion complexes between smaller crown ethers and quaternary ammonium cations which are difficult to observe by other methods, namely [18C6 + (CH₃)₄N]⁺ ion. Stability of the complexes between crown ethers containing aromatic ring and tetramethylammonium cation is enhanced by cation-Π interactions. The molecule of 18C6 does not contain aromatic rings, thus [18C6 + (CH₃)₄N]⁺ ion exists due to the formation of C–H···O hydrogen bonds. Such a complex is quite unusual, since C–H···O hydrogen bonds are very weak and usually coexist with other strong interactions.     

Preparation and characterization of poly(o-methoxyaniline)/Na-MMT clay nanocomposite via emulsion polymerization: Electrochemical studies of corrosion protection

A series of poly(o-methoxyaniline) (PMA)/Na⁺-montmorillonite (MMT) clay nanocomposite (Na⁺-PCN) materials have been successfully prepared by in situ emulsion polymerization in the presence of inorganic nanolayers of hydrophilic Na⁺-MMT clay with DBSA and APS as surfactant and initiator, respectively. The as-synthesized Na⁺-PCN materials were characterized by Fourier-transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).Na⁺-PCN materials in the form of coatings with low loading of Na⁺-MMT clay (e.g., 5 wt.%, CLMA5) on cold rolled steel (CRS) were found much superior in corrosion protection over those of neat PMA based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5 wt.% aqueous NaCl electrolyte. The molecular weight of PMA extracted from Na⁺-PCN materials and net PMA were determined by gel permeation chromatography (GPC) with NMP as eluant. Effects of material composition on the optical properties, electrical conductivity, thermal stability and surface morphology of neat PMA and/or a series of Na⁺-PCN materials, in the form of solution, powder-pressed pellet and fine powder, were also studied by ultraviolet-visible spectra, four-point probe technique, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively.     

Use of Microspherical Sulfonated Hypercrosslinked Polystyrene in Ion Chromatography

The possibility of applying sulfonated cation exchangers on the basis of hypercrosslinked polystyrene (HCPS) of different ion-exchange capacity for the ion-chromatographic separation of alkali metal and ammonium cations was demonstrated. The effect of the nature and concentration of the eluent, the temperature of the chromatographic column, additions of an organic solvent to the eluent, and the ion-exchange capacity of the sorbent on the retention of cations was examined. An unusual selectivity of the sorbent for lithium and ammonium cations was found; the elution order can change for the Li⁺/Na⁺ and Rb⁺/NH⁺ ₄ pairs depending on the nature of the eluent, the temperature, additions of an organic solvent, and the structural characteristics of the sorbent. When dilute solutions of nitric acid are used as the eluent, the following elution order of cations was obtained: Na⁺ < Li⁺ < K⁺ < NH⁺ ₄ < Rb⁺ < Cs⁺ Mg²⁺ < Sr²⁺ < Ca²⁺ < Ba²⁺. Under the optimum conditions of separation (1 mM solution of sulfuric acid, 20°C) on sulfonated HCPS with an ion-exchange capacity of 0.07 mequiv/g, the separation of ammonium and alkali metal cations was achieved within 17 min.     

FTIR and NMR studies of bis(oxaalkyl) sulphates(IV) and their complexes with proton and some metal cations

The complexation of Li⁺ and Na⁺ cations by three bis(oxaalkyl) sulphates(IV) was studied by FTIR and NMR on ¹H, ¹³C, ⁷Li and ²³Na nuclei. The NMR results have proved the formation of complexes and the fluctuation of Li⁺ and Na⁺ cations in respective circular arrangements. In the FTIR spectra of protonated sulphates intense continuous absorptions were observed indicating fast fluctuation of the protons in the respective multiminima potentials. The continuous absorptions in the far infrared region of the FTIR spectra of Li⁺ or Na⁺ complexes with three bis(oxaalkyl) sulphates(IV) indicate fast fluctuations of Li⁺ or Na⁺ cations between O-atoms of the oxaalkyl chains. The independence of the shape of the continua on the length of the oxaalkyl chains, i. e. the number of minima in the multiminima potential, demonstrates that the fluctuation of cations occurs in the respective circular arrangements.     

Advanced environmentally friendly anticorrosive materials prepared from water-based polyacrylate/Na-MMT clay nanocomposite latexes

A series of novel advanced environmentally friendly anticorrosive materials have been successfully prepared by effectively dispersing nanolayers of Na⁺-montmorillonite (Na⁺-MMT) clay into water-based polyacrylate latex (i.e., vinyl acrylic terpolymers). First of all, a polyacrylate latex was synthesized through co-polymerizing organic monomers of MMA, BMA and styrene (St) using conventional emulsion polymerization technique with SDS, 1-pentanol and KPS as surfactant, co-surfactant and initiator, respectively. Subsequently, the commercial purified hydrophilic Na⁺-MMT was effectively dispersing into the polyacrylate latex through the direct solution dispersion technique.The as-prepared neat polyacrylate and the series of water-based polyacrylate/Na⁺-MMT clay nanocomposite (Na⁺-PCN) materials were subsequently characterized by FTIR spectroscopy, XRD, TEM and GPC. The water-based Na⁺-PCN materials loaded with low content of Na⁺-MMT when in the form of coating on the cold rolled steel (CRS) coupons was found to be remarkably superior in anticorrosion efficiency over those of neat polyacrylate based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current, and impedance spectroscopy in saline. Effect of material composition on the molecular barrier, optical clarity and thermal stability were also studied by molecular permeability analysis, ultraviolet-visible transmission spectra, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Organo-PCN materials were also prepared as a control experiment for comparative studies.     

Nanospheres,Nanotubes, Toroids,and Gels with Controlled Macroscopic Chirality

The interaction of a highly dynamic poly(aryl acetylene) (poly‐ 1 ) with Li⁺, Na⁺_, and Ag⁺ leads to macroscopically chiral supramolecular nanospheres, nanotubes, toroids, and gels. With Ag⁺, nanospheres with M helicity and tunable sizes are generated, which complement those obtained from the same polymer with divalent cations. With Li⁺ or Na⁺, poly‐ 1 yields chiral nanotubes, gels, or toroids with encapsulating properties and M helicity. Right‐handed supramolecular structures can be obtained by using the enantiomeric polymer. The interaction of poly‐ 1 with Na⁺ produces nanostructures whose helicity is highly dependent on the solvation state of the cation. Therefore, structures with either of the two helicities can be prepared from the same polymer by manipulation of the cosolvent. Such chiral nanotubes, toroids, and gels have previously not been obtained from helical polymer–metal complexes. Chiral nanospheres made of poly(aryl acetylene) that were previously assembled with metal(II) species can now be obtained with metal(I) species.     

Neutral carrier potassium-selective electrodes with low resistances

Valinomycin-based electrodes for potassium are described which have resistances as low as 5 kΩ. Addition of a mixture of tetraphenylborate and a quaternary ammonium salt lowers the resistance to 1–3% of that without the additive. The electrode retains high selectivity for K⁺ over Na⁺ even in the presence of a large excess of the tetraphenylborate additive over the carrier.     

Nanospheres,Nanotubes, Toroids,and Gels with Controlled Macroscopic Chirality

The interaction of a highly dynamic poly(aryl acetylene) (poly‐ 1 ) with Li⁺, Na⁺_, and Ag⁺ leads to macroscopically chiral supramolecular nanospheres, nanotubes, toroids, and gels. With Ag⁺, nanospheres with M helicity and tunable sizes are generated, which complement those obtained from the same polymer with divalent cations. With Li⁺ or Na⁺, poly‐ 1 yields chiral nanotubes, gels, or toroids with encapsulating properties and M helicity. Right‐handed supramolecular structures can be obtained by using the enantiomeric polymer. The interaction of poly‐ 1 with Na⁺ produces nanostructures whose helicity is highly dependent on the solvation state of the cation. Therefore, structures with either of the two helicities can be prepared from the same polymer by manipulation of the cosolvent. Such chiral nanotubes, toroids, and gels have previously not been obtained from helical polymer–metal complexes. Chiral nanospheres made of poly(aryl acetylene) that were previously assembled with metal(II) species can now be obtained with metal(I) species.     

Absorption and fluorescence properties of acridinones,thioacridinones, aminoacridines and related crown ethers

We report a study on the absorptive and emissive properties of 9‐acridinones, 9‐thioacridinones and 9‐aminoacridines including six crown ether derivatives. The effect of solvents and of the addition of cations (Na⁺, K⁺, Ca2⁺ and Mg2⁺) on these properties has been studied. The absorption of the crown ether derivative of 9‐thioacridinone is sensitive to solvents while the fluorescence of crown ethers derived from 9‐aminoacridines shows some specificity towards cations. Empirical modeling was used to discuss the emission characteristics of these compounds.     

Monolithic ODS-silica gel column for determination of hydrogen, sodium, ammonium and potassium in acid rain by lon chromatography

Summary A monolithic ODS-silica gel column modified by saturating it with lithium dodecylsulfate (Li-DS) was firstly used to separate monovalent cations simultaneously including H⁺, Na⁺, NH₄ ⁺ and K⁺ by ion-chromatography (IC). Using an acidified 60 mM LiCl solution (pH 3.95, containing 0.10 mM Li-DS) as eluent, these monovalent cations were separated well in the order of Na⁺<NH₄ ⁺<K⁺<H⁺ within 3 min at a flow rate of 2.0 mL min⁻¹. The detection limits of these cations by this method with conductivity detection were 20.0 μM for Na⁺, 12.0 μM for NH₄ ⁺, 9.84 μM for K⁺ and 6.20 μM for H⁺. Acid rain water samples with a pH value less than 5.00 could be analyzed directly with this IC system.     

NMR, FTIR, ESI-MS and semiempirical study of a new 2-(2-hydroxyethoxy)ethyl ester of monensin A and its complexes with alkali metal cations

A new 2-(2-hydroxyethoxy)ethyl ester of monensin A (MON6) has been synthesized and its ability to form complexes with Li⁺, Na⁺ and K⁺ cations has been studied by ESI-MS, ¹H and ¹³C NMR, FTIR, and PM5 semiempirical methods. It is demonstrated that MON6 has been able to form stable complexes of 1:1 stoichiometry with monovalent metal cations. The structures of the complexes are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. In the structure of MON6 the oxygen atom of the CO ester group is involved in very weak bifurcated intramolecular hydrogen bonds with two hydroxyl groups whereas in the complexes of MON6 with monovalent metal cations the CO ester group is not engaged in any intramolecular hydrogen bonds. The structures of the MON6 and its complexes with Li⁺, Na⁺ and K⁺ cations are visualized.     

Liquid—liquid distribution of ion associates of tetraiodopalladate(II) with quaternary ammonium counter ions

The distribution behaviour of ion association of Pdl^2?₄ with ten quaternary ammonium cations between chloroform and an aqueous phase was examined and extraction constants (log K_ex) were determined. Linear relationships between log K_ex and the number of methylene groups in the quaternary ammonium ions were observed. Quantitative extraction of palladium was achieved with Zeph⁺ or TBA⁺; the molar absorptivity was 2.5 × 10⁴ l mol^?1 cm^?1 at 344 nm. The effect of other ions on the spectrophotometric determination of palladium, based on their extraction, is reported.     

Cation-binding properties of poly- and bis(benzo-21-crown-7)derivatives

Summary Poly- and bis(crown ether)s which contain the relatively large crown ether ring of benzo-21-crown-7 were synthesized, and their cation-binding properties for alkali metal cations were elucidated by solvent extraction and also conductometrically. The cation-binding ability was found to decrease in the order Cs⁺>Rb⁺>K⁺>Na⁺. They can extract alkali metal cations more efficiently than the corresponding monomeric analogue. The binding behaviour for some organic cations such as alkyl ammonium and guanidinium is also described.

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Kationen-Bindungsvermögen von Poly- und Bis(benzo-21-krone-7)-Derivaten

Zusammenfassung Poly- und Bis-kronenether mit dem relativ großen Kronenetherring Benzo-21-krone-7 wurden dargestellt und ihr Bindungsvermögen für Alkaliionen wurde durch Lösungsextraktion und auch konduktometrisch untersucht. Es ergab sich, daß das Bindungsvermögen in der Reihenfolge Cs⁺>Rb⁺>K⁺>Na⁺ abnimmt. Diese Substanzen können Alkaliionen wirksamer extrahieren als die entsprechenden Monomeren Analogen. Das Bindungsvermögen für einige organische Kationen, wie z.B. Alkylammonium und Guanidinium, wurde ebenfalls untersucht.

     

Synthesis and Characterisation of the Sodium and Lithium Cryptates of Macrobicyclic Ligands incorporating pyridine,bipyridine, and biisoquinoline units

Sythetic procedures have been deweloped for the preparation of sodium and lithium cryptates of the macrabicyclic ligands 1–11 containing pyridine, bipyridine, and biisoquinoline groups. They involve stepwise construction of the bicyclic system as will as direct macrobicyclisation procedures (Scheme 1) and give access to both symmetrical and dissymmetrical structures. Marked cation template effects have been found that facilitate the cyclisation processes. The ligands 1–11 were isolated as their cryptates with Na⁺ or Li⁺ cations.