M2Ga6Te10 (M: Li,Na): Two New Non‐metallic Filled β‐Manganese Phases – X‐ray and NMR Studies

Two new non‐metallic filled β‐manganese phases M₂Ga₆Te₁₀ (M: Li, Na) are obtained as black, homogeneous, microcristalline samples as well as single crystals by direct reaction of the elements. According to the single crystal structure determinations both compounds crystallize in space group R32 (No. 155, Z = 2) with the lattice constants: a = 1436.9(2), c = 1759.0(4) pm (T = 180 K, Li₂Ga₆Te₁₀) and a = 1458(1) pm, c = 1776.1(4) pm (T = 290 K, Na₂Ga₆Te₁₀). Their structures are characterized by tetrahedral close packings of Te^2–, corresponding to the arrangement of Mn atoms in β‐Mn. While Ga³⁺ ions are distributed in an ordered way over 12% of the tetrahedral holes, the M⁺ ions occupy all distorted octahedral (“metaprismatic”) holes. As the Li⁺ ions are too small they occupy off‐center positions inside the metaprisms. Positions with the strongest off‐centering can only be refined on the basis of a split model. MAS‐NMR measurements, including multiple quantum NMR, allowed the two different crystallographic M⁺ sites to be distinguished unambigously by separate ⁷Li and ²³Na signals, respectively. The assignment of the NMR signals was supported by measurements of samples in which Li⁺ was partly substituted by larger cations (Sn²⁺, Pb²⁺).     

Proton Intercalation/De‐Intercalation Dynamics in Vanadium Oxides for Aqueous Aluminum Electrochemical Cells

Understanding cation (H⁺, Li⁺, Na⁺, Al³⁺, etc.) intercalation/de‐intercalation chemistry in transition metal compounds is crucial for the design of cathode materials in aqueous electrochemical cells. Here we report that orthorhombic vanadium oxides (V₂O₅) supports highly reversible proton intercalation/de‐intercalation reactions in aqueous media, enabling aluminum electrochemical cells with extended cycle life. Empirical analyses using vibrational and x‐ray spectroscopy are complemented with theoretical analysis of the electrostatic potential to establish how and why protons intercalate in V₂O₅ in aqueous media. We show further that cathode coatings composed of cation selective membranes provide a straightforward method for enhancing cathode reversibility by preventing anion cross‐over in aqueous electrolytes. Our work sheds light on the design of cation transport requirements for high‐energy reversible cathodes in aqueous electrochemical cells.     

Lithium ions in the van der Waals gap of Bi2Se3 single crystals

Insertion/extraction of lithium ions into/from Bi₂Se₃ crystals was investigated by means of cyclic voltammetry. The process of insertion is reflected in the appearance of two bands on voltammograms at ∼1.7 and ∼1.5 V, corresponding to the insertion of Li⁺ ions into octahedral and tetrahedral sites of the van der Waals gap of these layered crystals. The process of extraction of Li⁺ ions from the gap results in the appearance of four bands on the voltammograms. The bands 1 and 2 at ∼2.1 and ∼2.3 V correspond to the extraction of a part of Li⁺ guest ions from the octahedral and tetrahedrals sites and this extraction has a character of a reversible intercalation/deintercalation process. A part of Li⁺ ions is bound firmly in the crystal due to the formation of negatively charged clusters of the (LiBiSe₂.Bi₃Se₄⁻) type. A further extraction of Li⁺ ions from the van der Waals gap is associated with the presence of bands 3 and 4 placed at ∼2.5 and ∼2.7 V on the voltammograms as their extraction needs higher voltage due to the influence of negative charges localized on these clusters.     

Properties and Applications of Cryptand‐22 Surfactant for Ion Transport and Ion Extraction

A non‐ionic cryptand‐22 surfactant consisting of a macrocyclic cryptand‐22 polar head and a long paraffinic chain (C₁₀H₂₁‐Cryptand‐22) was synthesized and characterized. The critical micellar concentration (CMC) of the cryptand surfactant in ROH/H₂O mixed solvent was determined by the pyrene fluorescence probe method. In general, the cmc of the cryptand surfactant increased upon decreasing the polarity of the surfactant solution. The cryptand surfactant also can behave as a pseudo cationic surfactant by protonation of cryptand‐22 or complexation with metal ions. Effects of protonation and metal ions on the cmc of the cryptand surfactant were investigated. A preliminary application of the cryptand surfactant as an ion‐transport carrier for metal ions, e.g., Li⁺, Na⁺, K⁺ and Sr²⁺, through an organic liquid‐membrane was studied. The transport ability of the cryptand surfactant for these metal ions was in the order: K⁺ ≥ Na⁺ < Li⁺ < Sr²⁺. A comparison of the ion‐transport ability of the cryptand surfactant with other macrocyclic polyethers, e.g., dibenzo‐18‐crown‐6, 18‐crown‐6 and benzo‐15‐crown‐5, was studied and discussed. Among these macrocyclic polyethers, the cryptand surfactant was the best ion‐transport carrier for Na⁺, Li⁺ and Sr²⁺ ions. Furthermore, a foam extraction system using the cryptand surfactant to extract the cupric ion was also investigated.     

A Colorimetric and Fluorimetric Chemodosimeter for Copper Ion Based on the Conversion of Dihydropyrazine to Pyrazine

In this research, we successfully synthesized and fully characterized the new compound 5,8,13,16,21,24‐hex‐(triisopropylsilyl)ethynyl)‐6,23‐dihydro‐6,7,14,15,22,23‐hexaza‐trianthrylene ( HHATA , brown color in a mixed solvent of CH₂Cl₂/CH₃CN 1:1, v/v, weakly blue fluorescent), which can be easily oxidized to 5,8,13,16,21,24‐hex‐(triisopropylsilyl)ethynyl)‐6,7,14,15,22,23‐hexazatrianthrylene ( HATA ) (yellow color in CH₂Cl₂/CH₃CN 1:1, v/v), red fluorescent) by Cu²⁺ ions. This reaction only proceeds efficiently in the presence of Cu²⁺ ions when compared with other common metal ions such as Fe³⁺, Co²⁺, Mn²⁺, Hg²⁺, Ni²⁺, Pb²⁺, Ag⁺, Mg²⁺, Ca²⁺, K⁺, Na⁺, and Li⁺. Our result suggests that this reaction can be developed as an effective method for the detection of Cu²⁺ ions.     

Silver(I)‐Selective PVC Membrane Potentiometric Sensor Based on a Recently Synthesized Calix[4]arene

A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dihydroxy‐calix[4]arene‐thiacrown‐4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10^?2?1.0×10^?6 M) with a slope of 53.8±1.6 mV per decade. It has a relatively fast response time (5–10 s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag⁺ ions over Pb²⁺, Cd²⁺, Co²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Sr²⁺, Mg²⁺, Ca²⁺, Li⁺, K⁺, Na⁺, NH₄⁺ ions and can be used in a pH range of 2–6. Only interference of Hg²⁺ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions.     

Chiral differentiation of the noscapine and hydrastine stereoisomers by electrospray ionization tandem mass spectrometry

Energy‐dependent collision‐induced dissociation (CID) of the dimers [2 M + Cat]⁺ of the noscapine and hydrastine stereoisomers was studied where Cat stands for Li⁺, Na⁺, K⁺ and Cs⁺ ions. These dimers were generated ‘in situ’ from the electrosprayed solution. The survival yield (SY) method was used for distinguishing the noscapine and hydrastine dimers. Significant differences were found between the characteristic collision energies (CE₅₀, i.e. the collision energy necessary to obtain 50% fragmentation) of the homo‐ (R,R; S,S) and heterochiral (R,S; S,R) stereoisomers. To distinguish the enantiomer pairs L‐, D‐tyrosine ([M + Tyr + Cat]⁺) and L‐, D‐lysine ([M + Lys + Cat]⁺) were used as chiral selectors. Furthermore, these heterodimers [M + amino acid + Cat]⁺ were also applied to determine the stereoisomeric composition. It was found that the characteristic collision energy (CE₅₀) of the noscapine and hydrastine homodimers ([2 M + Cat]⁺) was inversely proportional to the ionic radius of the cations. Furthermore, the structures of the dimers [2 M + Cat]⁺ were studied by high level quantum chemical calculations. Copyright © 2015 John Wiley & Sons, Ltd.     

Studies on heat-treated MPCF anodes in Li ion batteries

The intercalation/deintercalation of lithium ions into the heat-treated mesophase pitch-based carbon fibers (MPCF) was carried out in 1 M LiPF₆-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, volume ratio) solution at room temperature. LiC₆ became incorporated into the heat-treated MPCF via an Li⁺ intercalation process. The transition stage was observed by a charge-discharge curve, impedance spectrum, and X-ray diffraction (XRD) spectrum. From the observed results, we conclude that the initial intercalation of lithium ions proceeds not by a reversible pathway, but rather, an irreversible path. From the deintercalation to the continuous cycles the lithium ion is intercalated and deintercalated via a reversible pathway.     

Calix[4]pyrrole‐Based Heteroditopic Ion‐Pair Receptor That Displays Anion‐Modulated,Cation‐Binding Behavior

A new ditopic ion‐pair receptor 1 was designed, synthesized, and characterized. Detailed binding studies served to confirm that this receptor binds fluoride and chloride ions (studied as their tetraalkylammonium salts) and forms stable 1:1 complexes in CDCl₃. Treatment of the halide‐ion complexes of 1 with Group I and II metal ions (Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, and Ca²⁺; studied as their perchlorate salts in CD₃CN) revealed unique interactions that were found to depend on both the choice of the added cation and the precomplexed anion. In the case of the fluoride complex [ 1? F]^? (preformed as the tetrabutylammonium (TBA⁺) complex), little evidence of interaction with the K⁺ ion was seen. In contrast, when this same complex (i.e., [ 1? F]^? as the TBA⁺ salt) was treated with the Li⁺ or Na⁺ ions, complete decomplexation of the receptor‐bound fluoride ion was observed. In sharp contrast to what was seen with Li⁺, Na⁺, and K⁺, treating complex [ 1? F]^? with the Cs⁺ ion gave rise to a stable, receptor‐bound ion‐pair complex [Cs ?1? F] that contains the Cs⁺ ion complexed within the cup‐like cavity of the calix[4]pyrrole, which in turn was stabilized in its cone conformation. Different complexation behavior was observed in the case of the chloride complex [ 1? Cl]^?. In this case, no appreciable interaction was observed with Na⁺ or K⁺. In addition, treating [ 1? Cl]^? with Li⁺ produces a tightly hydrated dimeric ion‐pair complex [ 1? LiCl(H₂O)]₂ in which two Li⁺ ions are bound to the crown moiety of the two receptors. In analogy to what was seen in the case of [ 1? F]^?, exposure of [ 1? Cl]^? to the Cs⁺ ion gives rise to an ion‐pair complex [Cs ?1? Cl] in which the cation is bound within the cup of the calix[4]pyrrole. Different complexation modes were also observed when the binding of the fluoride ion was studied by using the tetramethylammonium and tetraethylammonium salts.     

A First‐Cycle Coulombic Efficiency Higher than 100 % Observed for a Li2MO3 (M=Mo or Ru) Electrode

The lithiation/de‐lithiation behavior of a ternary oxide (Li₂MO₃, where M=Mo or Ru) is examined. In the first lithiation, the metal oxide (MO₂) component in Li₂MO₃ is lithiated by a conversion reaction to generate nano‐sized metal (M) particles and two equivalents of Li₂O. As a result, one idling Li₂O equivalent is generated from Li₂MO₃. In the de‐lithiation period, three equivalents of Li₂O react with M to generate MO₃. The first‐cycle Coulombic efficiency is theoretically 150 % since the initial Li₂MO₃ takes four Li⁺ ions and four electrons per formula unit, whereas the M component is oxidized to MO₃ by releasing six Li⁺ ions and six electrons. In practice, the first‐cycle Coulombic efficiency is less than 150 % owing to an irreversible charge consumption for electrolyte decomposition. The as‐generated MO₃ is lithiated/de‐lithiated from the second cycle with excellent cycle performance and rate capability.     

Intermetallic Competition in the Fragmentation of Trimetallic Au–Zn–Alkali Complexes

Cationization is a valuable tool to enable mass spectrometric studies on neutral transition‐metal complexes (e.g., homogenous catalysts). However, knowledge of potential impacts on the molecular structure and catalytic reactivity induced by the cationization is indispensable to extract information about the neutral complex. In this study, we cationize a bimetallic complex [AuZnCl₃] with alkali metal ions (M⁺) and investigate the charged adducts [AuZnCl₃M]⁺ by electrospray ionization mass spectrometry (ESI‐MS). Infrared multiple photon dissociation (IR‐MPD) in combination with density functional theory (DFT) calculations reveal a μ³ binding motif of all alkali ions to the three chlorido ligands. The cationization induces a reorientation of the organic backbone. Collision‐induced dissociation (CID) studies reveal switches of fragmentation channels by the alkali ion and by the CID amplitude. The Li⁺ and Na⁺ adducts prefer the sole loss of ZnCl₂, whereas the K⁺, Rb⁺, and Cs⁺ adducts preferably split off MCl₂ZnCl. Calculated energetics along the fragmentation coordinate profiles allow us to interpret the experimental findings to a level of subtle details. The Zn²⁺ cation wins the competition for the nitrogen coordination sites against K⁺, Rb⁺, and Cs⁺ , but it loses against Li⁺ and Na⁺ in a remarkable deviation from a naive hard and soft acids and bases (HSAB) concept. The computations indicate expulsion of MCl₂ZnCl rather than of MCl and ZnCl₂.     

Highly Selective Lithium Transport through Crown Ether Pillared Angstrom Channels

Biological ion channels use the synergistic effects of various strategies to realize highly selective ion sieving. For example, potassium channels use functional groups and angstrom-sized pores to discriminate rival ions and enrich target ions. Inspired by this, we constructed a layered crystal pillared by crown ether that incorporates these strategies to realize high Li⁺ selectivity. The pillared channels and crown ether have an angstrom-scale size. The crown ether specifically allows the low-barrier transport of Li⁺. The channels attract and enrich Li⁺ ions by up to orders of magnitude. As a result, our material sieves Li⁺ out of various common ions such as Na⁺, K⁺, Ca²⁺, Mg²⁺ and Al³⁺. Moreover, by spontaneously enriching Li⁺ ions, it realizes an effective Li⁺/Na⁺ selectivity of 1422 in artificial seawater where the Li⁺ concentration is merely 25 μM. We expect this work to spark technologies for the extraction of lithium and other dilute metal ions.     

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.     

Intercalation compounds of TIS2 with lithium and transition metals LixMyTiS2 (M=Ti,Fe, Ni)

Conclusions The titanium disulfide intercalation compounds obtained that contained both lithium and transition metals with the composition Li_xMyTiS₂ (M=Ti, Fe, Ni) had an interlayer distance that was greater than in the original MyTiS₂, but less than in Li_xTiS₂ with the same lithium content.Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 478–483, March, 1987.     

The formation of flouride complexes of titanium(IV)

The complex formation equilibria between titanium(IV) and fluoride ions have been studied at 25°C in 3 M(Na)Cl ionic medium by measuring, with an ion selective electrode for F^?, the free HF concentration in acid Ti(IV) solutions. The [H⁺] was kept within 0.25 and I M where the predominant form of uncomplexed metal is the dihydroxotitanium(IV) ion, Ti(OH)²⁺₂. The potentiometric data have been explained by assuming Ti(OH)₂F⁺, TiF₄ and HTiF^?₆, with equilibrium constants given in Table 3. Within the accuracy of the present e.m.f. study, ±0.2 mV, no evidence for intermediate complexes bearing 2, 3 and 5 F^? was found.From a special series of measurements, carried out by replacing a large part of the Cl^? with ClO^?₄, it is concluded that no appreciable amount of Ti(IV)Cl complexes is formed at the 3 M level employed as ionic medium.     

A Coated Graphite Thorium‐Ion Selective Potentiometric Sensor Based on a Calix[4]arene Bearing Phosphoryl Groups

5,11,17,23‐Tetra‐tert‐butyl‐25,26,27,28‐tetrakis(diphenylphosphinoylmethoxy)calix[4]arene ( 1 )has been used for the preparation of a graphite coated thorium ion‐selective electrode (Th⁴⁺‐ISE). The plasticized PVC membrane containing 30% PVC, 58% ortho‐nitrophenyloctylether (NPOE), 4% sodium tetraphenylborate (NaTPB) and 8% ionophore was directly coated on a graphite rod. This sensor gave good Nernstian responses with a slope of 15.5 ± 0.1 mV/decade over a concentration range of 1 × 10^?5 ?1 × 10^?3 M of thorium ions with a limit of detection of 7.9 × 10^?6 M. The dynamic response time of the electrode to achieve a steady potential was found to be about 15 seconds. The potential of the prepared sensor was independent of the pH variation in the range 2.3–4.0. The selectivity relative to several mono‐, di‐ and tri‐valent metal ions, i.e. Li⁺, Na⁺, K⁺, Ag⁺, NH₄⁺, Sr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, La³⁺, Sm³⁺, Dy³⁺, Er³⁺ and Y³⁺ was examined. This electrode can be used for 6 months without any considerable divergences in the potential response. The sensor was successfully used as an indicator electrode for the potentiometric titration of a thorium solution using a standard solution of EDTA.     

Lithium versus Mono/Polyvalent Ion Intercalation: Hybrid Metal Ion Systems for Energy Storage

The energy storage by redox intercalation reactions is, nowadays, the most effective rechargeable ion battery. When lithium is used as intercalating agents, the high energy density is achieved at an expense of non‐sustainability. The replacement of Li⁺ with cheaper monovalent ions enables to make greener battery alternatives. The utilization of polyvalent ions instead of Li⁺ permits to multiplying the battery capacity. Contrary to Li⁺, the realization of quick and reversible intercalation of bigger monovalent and of polyvalent ions is a scientific challenge due to kinetic constraints, polarizing ion effects and Coulomb interactions. Herein we provide a vision how to make the intercalation of these ions feasible. The idea is to perform dual intercalation of ions having different charges, radii, preferred coordination and diffusion pathway topology. All these features are demonstrated by the recent knowledge on selective and non‐selective intercalation properties of oxides and polyanion compounds with layered and tunnel structures. Based on dual intercalation properties, the fabrication of hybrid metal ion batteries is presented and discussed.     

Comparative investigation of LiNbO3 crystals Raman spectra in the temperature range 100–400 K

We have investigated Raman spectra of congruent and stoichiometric LiNbO₃ crystals in the temperature range 100–450 K. Slope gradient is greater for the temperature dependence of band width associated with Nb⁵⁺ ions vibrations than that associated with Li⁺ ions vibrations in a lithium niobate crystal structure. This fact indicates that the anharmonicity of Nb⁵⁺ ions vibrations along the polar axis is greater compared to Li⁺ ions vibrations. It is likely that O^2– ions contribute to this anharmonicity. The O^2– ions vibrations are characterized by an anharmonic potential in the LiNbO₃ crystal structure. The O^2– ions vibrations according to ab initio calculations strongly interact with vibrations of Nb⁵⁺ ions. We have found that the temperature dependence of the fundamental bands intensity is nonmonotonic and the “extra bands” intensity is strictly linear.     

Ionophores in Rubidium Ion‐Selective Membrane Electrodes

Binaphthyl‐based crown ethers incorporating anthraquinone, benzoquinone, and 1,4‐dimethoxybezene have been synthesized and tested for Rb⁺ selective ionophores in the poly(vinyl chloride) (PVC) membrane. The membrane containing NPOE gave a better Rb⁺ selectivity than those containing either DOA or BPPA as a plasticizer. The response was linear within the concentration range of 1.0×10^?5–1.0×10^?1 M and the slope was 54.7±0.5 mV/dec. The detection limit was determined to be 9.0×10^?6 M and the optimum pH range of the membrane was 6.0–9.0. The ISE membrane exhibits good selectivity for Rb⁺ over ammonium, alkali metal, and alkaline earth metal ions. Selectivity coefficients for the other metal ions, log K^Pot were ?2.5 for Li⁺, ?2.4 for Na⁺, ?2.0 for H⁺, ?1.0 for K⁺, ?1.2 for Cs⁺, ?1.6 for NH₄⁺, ?4.5 for Mg²⁺, ?5.0 for Ca²⁺,?4.9 for Ba²⁺. The lifetime of the membrane was about one month.     

On the hydrolysis of the titanium(IV) ion in chloride media

Determinations of the [Ti(IV)]/[Ti(III) ratio in solutions of titanium(IV) chloride equilibrated with H₂(g), at 25°C in 3 M (Na)Cl ionic medium, have indicated the predominance of the Ti(OH)₂²⁺ species in the concentration ranges 0.5 ? [H⁺] ? 2 M and 1.5 x 10^?3 ? [Ti(IV)] ? 0.05 M. From the equilibrium data the reduction potential has been evaluated Ti(OH)₂²⁺ + 2 H⁺ + e ? Ti³⁺ + 2H₂O, E_oH = (7.7 ± 0.6) x 10^?3 V. The acidification reactions of Ti(OH)₂²⁺ were also studied in 12 M(Li)Cl medium at 25°C by measuring the redox potential of the Ti(IV)/Ti(III) couple as a function of [H⁺]. The potentiometric data in the acidity range 0.3 ? [H⁺] ? 12 M have been explained by assuming Ti⁴⁺ + e ? Ti³⁺, E_o = 0.202 ± 0.002 V Ti⁴⁺ + H₂O ? TiOH³⁺ + H⁺, log K_a1 = 0.3 ± 0.01 Ti⁴⁺ + 2H₂O ? Ti(OH)₂²⁺ + 2H⁺, log K_a1K_a2 = 1.38 ± 0.05.