Seventeen new 14- and 15-crown-formazans: their synthesis and evaluation in spectrophotometric determination of lithium

A number of new crown-formazans with 14 and 15 membered rings have been synthesized, characterized and investigated as selective spectrophotometric chelating agents for lithium. The effect of sodium ion concentration on the background lithium signal was studied. A comparative study for the sensitivity of these new crown-formazans in spectrophotometric determinations was studied and compared with those reported previously. The three new 14- and 15-crown-formazans 4a–c containing the pyridyl N-oxide at the formazyl carbon showed the highest selectivity to lithium determination in the presence of sodium ion.     

Evaluation of some new 14- and 15-crown-formazans as carriers in cesium ion selective electrodes

A number of new crown-formazans with 14 and 15 membered rings have been investigated as selective neutral carriers in cesium ion selective electrodes. Two plasticizers (NPOE and NPBnE) were studied. The new 14-crown-formazan 4a containing the 4-pyridyl N-oxide at the formazyl carbon exhibited the highest selectivity in cesium ion selective electrodes, especially towards the two low selectivity monovalent ions K⁺ and NH4⁺. Also, membranes containing the plasticizer NPBnE showed better cesium selectivity relative to most ions than those containing NPOE. Membranes containing 4a and variable compositions of plasticizers, potassium tetrakis-(p-chlorophenyl)borate (KTpClPB), and trioctylphosphine oxide (TOPO) were studied in order to prepare an electrode with the optimum cesium selectivity. The highest selectivity for cesium was achieved with the two electrodes designated d and e with membranes containing the ionophore 4a, NPBnE and KTpClPB with and without TOPO. Selectivities are reported relative to sodium, potassium, barium, calcium, ammonium, lithium, cobalt, and magnesium.     

Evaluation of some new 14- and 15-crown-formazans as carriers in cesium ion selective electrodes

A number of new crown-formazans with 14 and 15 membered rings have been investigated as selective neutral carriers in cesium ion selective electrodes. Two plasticizers (NPOE and NPBnE) were studied. The new 14-crown-formazan 4a containing the 4-pyridyl N-oxide at the formazyl carbon exhibited the highest selectivity in cesium ion selective electrodes, especially towards the two low selectivity monovalent ions K(+) and NH4(+). Also, membranes containing the plasticizer NPBnE showed better cesium selectivity relative to most ions than those containing NPOE. Membranes containing 4a and variable compositions of plasticizers, potassium tetrakis-(p-chlorophenyl)borate (KTpClPB), and trioctylphosphine oxide (TOPO) were studied in order to prepare an electrode with the optimum cesium selectivity. The highest selectivity for cesium was achieved with the two electrodes designated d and e with membranes containing the ionophore 4a, NPBnE and KTpClPB with and without TOPO. Selectivities are reported relative to sodium, potassium, barium, calcium, ammonium, lithium, cobalt, and magnesium.     

Spectrophotometric determination of lithium ion with the chromogenic crown ether, 2″,4″-dinitro-6″-trifluoromethylphenyl-4′-aminobenzo-14-crown-4

A spectrophotometric method of determining alkali metal ions with a chromogenice crown ether reagent was found to be more selective and sensitive than an ion-pairing method based on the same size of crown ether cavity. It is shown that in the ion-pairing method, the sensitivity toward lithium ion was 5.685 × 10^?4 absorbance/mg l^?1, with sodium interfering at 300 mg l^?1. The chromogenic crown ether, 2″,4″-dinitro-6″-trifluoromeethylphenyl-4′-aminobenzo-14-crown-4, was much superior to benzo-14-crown-4. The sensitivity of the chromogenic crown ether was 1.69 × 10^?3 absorbance/mg l^?1. This represents a three-fold increase in sensitivity and less reagent is needed (2 × 10^?4 M for the chromogenic method versus 1.4 × 10^?3 M for ion-pairing). Interference from sodium decreased to 3000 mg l^?1. The reagent was used to determine lithium ion in treated blood serum samples in both a batch and flow injection method and results were compared with data obtained with atomic absorption; excellent agreement was obtained in all cases.     

Synthesis and potentiometric selectivity study of new spiro-14-crown-4 derivatives

Abstract

Four new compounds with 14-crown-4 attached to spirocyclopentane or spirocyclohexane were synthesized and tested for potentiometric selectivity for lithium ion in polyvinyl chloride membrane electrodes. Four plasticizers were studied and the addition of tri-octylphosphine oxide (TOPO) was investigated. One ionophore exhibited a sodium/lithium selectivity, K^pot _Li,Na by the matched potential method of 0.0028 in the presence of 1% TOPO, using o-nitro-phenylphenyl ether as plasticizer. Selectivities are reported for sodium, potassium, nickel, cobalt, barium and calcium.     

Synthesis of N-octylmonoaza-15-crown-5 having a dodecylphosphoric acid functional group and the binding ability toward alkali metal cations

A new N-octylmonoaza-15-crown-5 having an alkylphosphoric acid functional group ( 3c ) was synthesized. It was revealed that 3c selectively transported sodium ion under neutral source phase/acidic receiving phase condition, and selectively transported lithium ion under basic source phase/acidic receiving phase condition. From an ir and ¹³C nmr spectral study of the lithium hydroxide and sodium thiocyanate complexes of 3c , it is suggested that 3c does not incorporate cations into the three dimensional cavity using the crown ring and the phosphoric acid site, but that the crown and the phosphoric acid sites act on the cations independently; only the crown ether site of 3c significantly coordinates to the cations under neutral source phase condition, and the phosphate anion is mainly employed under basic conditions.     

State in solution, structure, and regioselectivity of reactions of the lithium 1-(2-methoxyphenyl)-3,3-diphenylpropyne derivative

According to the spectrophotometric data, the lithium 1-(2-methoxyphenyl)-3,3-diphenylpropyne derivative in diethyl ether exists as contact ion pairs, while in THF, according to the spectrophotometric and¹³C NMR data, solvent-separated ion pairs are predominantly formed. According to the¹³C NMR data, the carbanion in the solventseparated ion pairs has a structure close to the propargylic type. The regioselectivity of reactions of the lithium derivative with ethyl halides in diethyl ether, THF, and hexamethyphosphoramide, with benzyl chloride in the first two solvents, and with methanol in THF were studied. The protonation with methanol proceeds exclusively at the allenylic center (C-1) while the ethylation and especially benzylation proceed predominantly at the propargylic center (C-3). The selectivity of ethylation of the propargylic center of both solvent-separated ion pairs in THF and contact ion pairs in diethyl ether increases as the hardness of the ethylating agent increases, and in the case of the same ethyl halide, the selectivity increases from the solvent-separated ion pairs to the contact ion pairs. The spectral data obtained and the data on changes in the regioselectivity do not allow one to believe that the contact ion pairs of the lithium derivative in ether exhibit the intramolecular coordination of the lithium cation to the methoxy group, which might lead to the allenylic structure of contact ion pairs of this derivative. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2043–2051, November, 1997.     

Chlorine Dioxide–Iodine–Sodium Thiosulfate Oscillating Reaction Investigated by the UV–Vis Spectrophotometric Method

A new chlorine dioxide–iodine–sodium thiosulfate chemical oscillatory reaction was studied by the UV–Vis spectrophotometric method. The initial concentrations of sodium thiosulfate, chlorine dioxide, iodine, sulfuric acid, and pH have great influences on the oscillations observed at wavelength 238 nm. The oscillations occur as long as the reactants are mixed. The amplitude and the number of oscillations are associated with the initial concentrations of reactants. The equations for the triiodide ion reaction rate changes with reaction time and the initial concentrations in the oscillation stage are an attenuation sine function. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.     

Inorganic functional materials: optimization of properties by structural and compositional control

A review is given of the strategies used to dope inorganic solids and the consequences for properties such as ionic and electronic conductivity. Doping mechanisms involve either substitution of foreign ions onto lattice sites, creation of vacancies on either cation or anion sites, or population of normally empty interstitial sites by either anions or cations. Mechanisms for charge compensation associated with aliovalent doping are reviewed and examples are given in the fields of solid state ionics and high-temperature superconductivity. The strategies used for targeting materials with new properties are reviewed, including a surprising number of cases where startling new properties are encountered in well-known materials. Specific examples discussed include MgB2 superconductor, Na beta-alumina sodium ion conductor, Ca12Al14O33 oxide ion conductor, LiCoMnO4 lithium battery cathode, doped Li4SiO4 tunable lithium ion conductor, and La-doped BaTiO3 ferroelectric, which can be either semiconducting or insulating. Examples are also given of a curious observation that extraordinary properties are often encountered in materials that are on the edge of stability, either structurally or compositionally or at the crossover between different property types.     

Extraction and Spectrophotometric Determination of Diclofenac in Pharmaceuticals

A new simple, rapid and sensitive spectrophotometric method has been developed for the determination of diclofenac sodium (Dicl) in pharmaceutical preparations. This method is based on the reaction of diclofenac sodium with an analytical reagent 1,3,3‐trimethyl‐5‐thiocyanato‐2‐[3‐(1′,3′,3′‐trimethyl‐3′‐H‐indol‐2′‐ylidene)‐propenyl]‐indolium cloride (TIC) at pH 8.0‐11.0 and the extraction of ion associate colored complex. Optimal conditions for the complex formation between Dicl and TIC were studied. This ion associate complex (1:1) was detected and extracted with toluene and an absorption maximum at 566.2 nm against a blank reagent. The calibration graph was linear from 0.9‐11.0 μg/mL of diclofenac and the detection limit was 0.86 μg/mL.     

Dynamics of three-component exchange on a cationite with lithium manganese spinel structure

The dynamics of the sorption of lithium ions on a cationite with lithium manganese spinel structure from neutral solutions against the background of a large amount of sodium ions was studied. It was demonstrated that the dynamics of the ion exchange of these ions from their mixed solutions differs significantly from that observed for their individual solutions. The experimental results can be explained by assuming that, at a large concentration of sodium ions in the solution, they saturate the surface of the cationite and that lithium ions are predominantly exchanged for sodium ions. This assumption is supported by the results of a mathematical modeling.     

A composite based on sodium germanate and reduced graphene oxide: Synthesis from peroxogermanate and application as anode material for lithium ion batteries

A composite based on sodium germanate and reduced graphene oxide was obtained for the first time by precipitating the initial peroxogermanate on a graphene oxide followed by heat treatment in vacuum. According to powder X-ray diffraction, sodium germanate crystallizes during the heat treatment in vacuum at 500°C. Scanning transmission electron microscopy examination showed that sodium peroxogermanate nanoparticles form a thin film on the surface of graphene oxide flakes. The electrochemical characteristics of composites obtained with different heat treatment conditions were studied as the anodes of lithium ion batteries.     

Lithium Ion Association with Sodium Phytate and the Effects on the Conformational Equilibria. Implications in the Physiological Effects of Lithium

Abstract

³¹P NMR was employed to examine the solution interactions of lithium and potassium ions with sodium phytate. The phytate molecular conformation was found to be pH and concentration dependent. The conformational equilibria of sodium phytate in aqueous solution was not affected by the addition of potassium ions, however, it was influenced by added lithium ions and was dependent on lithium ion concentration. Furthesmore, the phytate molecule showed some selectivity for lithium ion association over potassium and sodium ions. Possible implications in the physiological effects of lithium are discussed.     

Development of reliable analytical method for extraction and separation of thorium(IV) by Cyanex 272 in kerosene

A simple and selective spectrophotometric method has been developed for the extraction and separation of thorium(IV) from sodium salicylate media using Cyanex 272 in kerosene. Thorium(IV) was quantitatively extracted by 5 × 10⁻⁴ M Cyanex 272 in kerosene from 1 × 10⁻⁵M sodium salicylate medium. The extracted thorium(IV) was stripped out quantitatively from the organic phase with 4.0 M hydrochloric acid and determined spectrophotometrically with arsenazo(III) at 620 nm. The effect of concentrations of sodium salicylate, extractant, diluents, metal ion and strippants has been studied. Separation of thorium(IV) from other elements was achieved from binary as well as multicomponent mixtures such as uranium(VI), strontium(II), rubidium(I), cesium(I), potassium(I), Sodium(I), lithium(I), lead(II), barium(II), beryllium(II) etc. Using this method separation and determination of thorium(IV) in geological and real samples has been carried out. The method is simple, rapid and selective with good reproducibility (approximately ±2%).     

锂钠合金的原位电化学制备及“锂+钠”共储特性

锂钠合金相较于单一锂或者单一钠具有更优异的性能,以钠金属为正极、锂金属为负极,以LiPF₆、NaClO₄以及锂钠混合离子电解液作为电解液,组装成纽扣电池,在梯度电流密度下进行充放电,成功实现了锂钠合金的原位电化学制备。得益于锂、钠双电化学活性离子的协同效应,不同钠含量的锂钠合金为负极的锂钠混合离子电容器均呈现良好的电化学性能。尤其是低钠量的锂钠合金负极,添加NaClO₄电解液时,活化的柠檬酸钾衍生碳(SCDC-活化)正极在1 A/g电流密度下循环300圈时仍能保持238 mA·h/g的比容量和99%的容量保持率。高钠量的锂钠合金负极,添加锂钠混合离子电解液时,SCDC-活化呈现了319 mA·h/g的比容量,并在循环1040圈时仍能保持93 mA·h/g的高比容量和98%的容量保持率。     

Liquid chromatography/electrospray ionization mass spectrometric characterization of Harpagophytum in equine urine and plasma

A method has been developed for the analysis and characterization in equine urine and plasma of iridoid glycosides: harpagide, harpagoside and 8-para-coumaroyl harpagide, which are the main active principles of Harpagophytum, a plant with antiinflammatory properties. The method involves liquid chromatography coupled with positive electrospray ionization mass spectrometry. The addition of sodium or lithium chloride instead of formic acid in the eluting solvent has been studied in order to enhance the signal and to modify the ion's internal energy. Fragmentation pathways and associated patterns are proposed for each analyte. A comparison of three types of mass spectrometer: a 3D ion trap, a triple quadrupole and a linear ion trap, has been conducted. The 3D ion trap was selected for drug screening analysis whereas the linear ion trap was retained for identification and quantitation analysis.     

Homo- and heterocomplexes of sodium and lithium amides--structures in solution

Addition of the chiral amine (S)-methyl(1-phenyl-2-pyrrolidinoethyl)[15N]amine (1) to a large excess of nBuNa resulted in the formation of a mixed sodium amide/nBuNa complex. This is the first observation of such a complex. Addition of nBuLi to the chiral sodium amide dimer 3 gave a new mixed lithium/sodium amide 5. The use of 15N,6Li coupling constants showed that the lithium in 5 occupied the tetracoordinated site. The use of chiral sodium amide 3 in the desymmetrization of cyclohexene oxide gave a modest enantiomeric excess (ee) of 37%. The corresponding lithium amide gave an ee of 70% of the same enantiomer. This is the first example of the comparison of asymmetric induction by sodium as cation with that of lithium.     

Complexes of sodium and lithium borohydrides with macrocyclic polyethers

A method for the synthesis of complexes of sodium and lithium borohydrides with crown ethers is proposed. The complexes of sodium borohydride with benzo-15-crown-5, 4′-aminobenzo-15-crown-5, dibenzo-18-crown-6, and diaza-18-crown-6 and the complexes of lithium borohydride with benzo-15-crown-5 and dibenzo-18-crown-6 are synthesized. These complexes can be used for the preparation of hydrogen in their reactions with methanol. The complex formation does not affect the purity of hydrogen formed.     

锂/钠离子电池材料的固体核磁共振研究进展

固体核磁共振技术是一种定量分析固体材料结构与组成的强有力手段,结合固体核磁共振和常规x-射线衍射(XRD)、 x-射线吸收谱(XAS)等表征方法可对锂/钠离子电池材料在电化学反应中的结构演化过程进行全面的分析. 例如通过固体核磁共振研究, 可获得不同合成与修饰条件下, 锂/钠离子电池电极和电解质材料体相以及电极/电解质界面层的化学组成、局域结构和离子扩散动力学等信息,为高性能电池材料的设计和研发提供重要的基础数据. 本文结合本课题组的研究工作,综述了近三年来国内外固体核磁共振技术在锂/钠离子电池电极、电解质材料以及固体电解质界面膜（SEI）研究中的应用和进展.     

Development of NaNO2–O2 system as an oxidant at uranium leaching processes

A process of ferrous ion oxidation by sodium nitrite in sulfate uranium in situ leaching solutions was investigated. Kinetic, spectrophotometric, and heat effect studies have been made in order to investigate the chemistry of the oxidation process. As a result the method of ferrous ion oxidation in uranium in situ leaching solution was developed that makes possible to decrease sodium nitrite consumption by 20?C30 times comparing with traditional oxidation technique. It was founded also that process of ferrous ion oxidation can be conducted with partial sodium nitrite recirculation.