Interfacial Synthesis: Amphiphilic Monomers Assisted Ultrarefining of Mesoporous Manganese Oxide Nanoparticles and the Electrochemical Implications

Amphiphilic monomers, namely pyrrole and aniline, were used to reduce permanganate ion (MnO4–) at the dichloromethane/water interface for the preparation of ultrafine manganese oxide (MnOx, x ≤ 2) nanoparticles (NPs). These monomers did not undergo polymerization upon oxidation by MnO4–, but exerted an interesting effect of ultrarefining the produced MnOx NPs from reducing MnO4– at the organoaqueous interface. This was attributed to the ability of the monomer to access the interfacial reaction sites from both organic and aqueous phases, and hence retard the as-produced MnOx nuclei from aggregation at the interface. Such obtained products were mesoporous matrixes of three-dimensionally interconnected and uniform pseudospherical MnOx NPs (o-aminophenol, to reduce MnO4– produced a composite of nanobelts of poly(o-aminophenol) embedded in micrometer-sized MnOx blocks. The ultrafine MnOx NPs prepared from using aniline or pyrrole exhibited highly capacitive behavior in aqueous Na2SO4, promising their use in supercapacitors. It was also found that the MnOx NPs prepared from pyrrole-assisted synthesis possessed higher specific capacitance than that from aniline-assisted synthesis, despite the latter having a higher specific surface area. This difference is discussed in terms of crystallographic properties and water contents of these two samples

Voltammetric Studies of Through-Space and Through-Bond Electrostatic Interactions in Alkyl Linked Ferrocene and Benzoaza-15-crown-5 Receptor Molecules in Acetonitrile

Six new ferrocene alkyl-benzoaza-15-crown-5 molecules with different alkyl spacer lengths were synthesized and investigated by voltammetry in acetonitrile. Their mean potentials (E°‘) were more negative than that of ferrocene. The changes were greater for the bis-substituted ligands than for the monosubstituted ones. Increasing the alkyl spacer length shifted E°‘ negatively from −CH2− to −(CH2)2− but positively from −(CH2)2− to −(CH2)4−. This unusual variation is attributed to the combined electron donating and withdrawing influences and also the steric effect from the substituents on the ferrocene moiety. Analyses of the potentials of the molecules and their fully protonated forms suggested intramolecular electrostatic signaling through not only the space but also the alkyl chain which is usually considered to be an insulator for through-bond communication. Diffusion coefficients with insignificant differences between the receptors and their fully protonated forms were derived from cyclic voltammograms, suggesting insignificant further conformational variation upon protonation

Bis(calix[4]diquinone) Receptors: Cesium- and Rubidium-Selective Redox-Active Ionophores

A new class of redox-active ionophore comprised of two calix[4]diquinone moieties connected through either alkylene or pyridylene linkages has been developed. Spectroscopic and electrochemical investigations, X-ray crystal structure analyses, and molecular modeling studies show butylene- and propylene-linked members of this family of redox-active receptors exhibit remarkable selectivity preferences and substantial electrochemical recognition effects toward cesium and rubidium cations

Switching on Fast Lithium Ion Conductivity in Garnets: The Structure and Transport Properties of Li_3+<i>x</i>Nd₃Te_2−<i>x</i>Sb_<i>x</i>O₁₂

Polycrystalline samples of the garnets Li3+xNd3Te2−xSbxO12 have been prepared by high temperature solid state synthesis. X-ray and neutron powder diffraction data show that all compounds crystallize in the space group Ia3̅d with lattice parameters in the range 12.55576(12) Å for x = 0.05 to 12.6253(2) Å for x = 1.5. The lithium is distributed over a mixture of oxide tetrahedra and heavily distorted octahedra. Increasing the lithium content in these compounds leads to the introduction of vacancies onto the tetrahedral position and an increasing concentration of lithium found in the octahedra. The latter exhibit considerable positional disorder with two lithium cations positions within each octahedron. Impedance measurements show fast ion conduction with an activation energy of ca. 0.59(6) eV that is largely invariant with composition. Solid-state Li NMR measurements indicate that there is no exchange of lithium between the different coordination environments. These results indicate that lithium conduction in the garnet structure occurs exclusively via a network of edge-linked distorted oxide octahedra and that the tetrahedrally coordination lithium plays no part in the transport properties

Bis(calix[4]diquinone) Receptors: Cesium- and Rubidium-Selective Redox-Active Ionophores

A new class of redox-active ionophore comprised of two calix[4]diquinone moieties connected through either alkylene or pyridylene linkages has been developed. Spectroscopic and electrochemical investigations, X-ray crystal structure analyses, and molecular modeling studies show butylene- and propylene-linked members of this family of redox-active receptors exhibit remarkable selectivity preferences and substantial electrochemical recognition effects toward cesium and rubidium cations

LiAlO₂‑Modified Li Negative Electrode with Li₁₀GeP₂S₁₂ Electrolytes for Stable All-Solid-State Lithium Batteries

Lithium (Li) metal has an ultrahigh specific capacity in theory with an extremely negative potential (versus hydrogen), receiving extensive attention as a negative electrode material in batteries. However, the formation of Li dendrites and unstable interfaces due to the direct Li metal reaction with solid sulfide-based electrolytes hinders the application of lithium metal in all-solid-state batteries. In this work, we report the successful fabrication of a LiAlO2 interfacial layer on a Li/Li10GeP2S12 interface through magnetic sputtering. As LiAlO2 can be a good Li+ ion conductor but an electronic insulator, the LiAlO2 interface layer can effectively suppress Li dendrite growth and the severe interface reaction between Li and Li10GeP2S12. The Li@LiAlO2 200 nm/Li10GeP2S12/Li@LiAlO2 200 nm symmetric cell can remain stable for 3000 h at 0.1 mA cm–2 under 0.1 mAh cm–2. Moreover, unlike the rapid capacity decay of a cell with a pristine lithium negative electrode, the Li@LiAlO2 200 nm/Li10GeP2S12/LiCoO2@LiNbO3 cell delivers a reversible capacity of 118 mAh g–1 and a high energy efficiency of 96.6% after 50 cycles. Even at 1.0 C, the cell with the Li@LiAlO2 200 nm electrode can retain 95% of its initial capacity after 800 cycles

Synthesis, Characterization, and Electrochemical Properties of Diruthenium Complexes Bridged by Anthraquinones

We have prepared four isomeric binuclear ruthenium complexes, in which two ruthenium units have been attached to the 1,4- (4a), 1,5- (4b), 1,8- (4c), or 2,6-positions (4d) of a central anthraquinone (Aq) moiety, leading to packed (4c) or extended (4a,b,d) topologies. All of these bimetallic complexes were fully characterized by elemental analysis, 1H, 13C{1H}, and 31P NMR{1H} spectrometry, and UV/vis spectrophotometry. Moreover, the structures of 4a,b were established by X-ray crystallography. The electrochemical properties of the stable binuclear ruthenium complexes 4a−d were investigated, revealing that the two metal centers in 4a−c could interact with each other through an anthraquinone bridge, suggesting that the electron-withdrawing carbonyl chain actually functions as an effective bridge

Synthesis, Characterization, and Electrochemical Properties of Diruthenium Complexes Bridged by Anthraquinones

We have prepared four isomeric binuclear ruthenium complexes, in which two ruthenium units have been attached to the 1,4- (4a), 1,5- (4b), 1,8- (4c), or 2,6-positions (4d) of a central anthraquinone (Aq) moiety, leading to packed (4c) or extended (4a,b,d) topologies. All of these bimetallic complexes were fully characterized by elemental analysis, 1H, 13C{1H}, and 31P NMR{1H} spectrometry, and UV/vis spectrophotometry. Moreover, the structures of 4a,b were established by X-ray crystallography. The electrochemical properties of the stable binuclear ruthenium complexes 4a−d were investigated, revealing that the two metal centers in 4a−c could interact with each other through an anthraquinone bridge, suggesting that the electron-withdrawing carbonyl chain actually functions as an effective bridge