Proton conductivity of calix[4]arene-para-sulfonic acids

The proton conductivity of hydrates of calix[4]arene-para-sulfonic acids is studied. The high proton conductivity is observed at ambient temperatures in the wide ranges of environmental humidity and, correspondingly, water content in the hydrate. For the air humidity of 10 rel. %, the conductivity of compounds is 10^?4-10^?3 S cm^?1 and approaches 10^?2-10^?1 S cm^?1 as the humidity increases up to 70 rel. %.     

Modeling the Effect of Dimethylsulfoxide on the Energy of Interaction of Ions in Nafion-Like Membranes

Russian Journal of Physical Chemistry A - Quantum chemical modeling is performed for the distancing of lithium and ammonium cations from the –O–CF2–CF2–SO$$_{3}^{ - }$$...     

Effect of Perchloric Acid on Proton-Conducting Properties of Sulfonated Calix[4]Arene

Calix[4]arenesulfonic acid complexation with perchloric acid is studied. The stoichiometric composition of the complex is shown to be calix[4]arene/HClO₄ = 1/1. The complex is most stable against humidity changes as far as its proton-conducting properties are concerned. Its specific proton conductivity varies from 3 × 10^–3 to 5 × 10^–2 S/cm; the conductivity activation energy is 0.16 ± 0.04 eV. The studying of the effect of HClO₄ amount on the samples’ physico-chemical properties at low humidity showed the proton transfer in the material to be determined by the crystallites’ bulk, rather than surface, characteristics.     

Proton conductivity of calix[n]arene-para-sulfonic acids (n = 4, 8)

High proton conductivity in calix[n]arene-para-sulfonic acid hydrates (n = 4, 8) reaching a value of 10^?1 Ohm^?1 cm^?1 at a relative humidity of 80% was revealed for the first time. This value is close to the record conductivity of solid proton conductors and acid water solutions. The dependence of proton transfer parameters and water quantity in the title compounds dependent on the relative humidity of air was investigated.     

Percolation model of conductivity of calix[n]arene-p-sulfonic acids

Proton conductivity of special class of aromatic sulfonic acids is described, in particular, calixarene sulfonic acids that consist of flat anionic layers interlinked by labile two-dimensional hydrogen-bond network. High proton conductivity of their hydrates was observed earlier. The dependence of their transport characteristics (the proton conductivity, the activation energy of conductivity) was shown to have threshold character. The studied systems’ behavior is described on basis of percolation model that assumes changing of the proton transport mechanism at low water content in the structure.     

Aspects of proton transport in calix[6]arene sulfonic acid

The features of proton transport and proton hydration shell structure of calix[6]arene sulfonic acid were studied. XRD and NMR data indicate the existence of crystalline and amorphous phases and various conformations in the acid structure. The hydration process occurs in three stages by thermal analysis and IR spectroscopy. The change in the composition of the hydrate affected the conductivity only at low humidity; an inverse relationship between the water uptake and the activation energy of conductivity is observed in the entire investigated range of humidity.     

Arbuzov chemistry with chlorofullerene C(60)Cl(6): a powerful method for selective synthesis of highly functionalized [60]fullerene derivatives

We report Arbuzov-type reactions of chlorofullerene C(60)Cl(6) with trialkyl phosphites producing highly functionalized fullerene derivatives C(60)[P(O)(OR)(2)](5)H with high yields. The designed family of [60]fullerene phosphonic acids and their esters showed unusual properties which might find valuable material science applications.     

Modeling of processes in fuel cells based on sulfonic acid membranes and platinum clusters

The density functional theory with account for gradient correction (DFT/PBE) and periodical boundary conditions was used to model the main stages of processes occurring in hydrogen low-temperature fuel cells. Modeling was carried out at the example of calculation of catalytic anodic and cathodic processes occurring on the surface of the Pt₁₉ catalyst supported on a SnO₂ and water adsorption processes on the surface of a membrane represented by a crystal of metisylene sulfonic acid dihydrate [(CH₃)₃C₆H₂SO ₃ ^? · H₅O ₂ ⁺ ]. It was shown that the most energy-efficient process in the membrane is formation of crystals, in which two stoichiometric water molecules correspond to a single SO₃H group. Superstoichiometric water is adsorbed on the crystal surface with the adsorption energy of 0.3–0.6 eV; its transition inside the crystal is energy-consuming (2 eV). Barriers of surface proton conductivity are 0.2–0.3 eV.     

Crystalline hydrates of calix[4]arene-<Emphasis Type="Italic">para</Emphasis>-sulfonic acid with <Emphasis Type="Italic">n</Emphasis> (<Emphasis Type="Italic">n</Emphasis> = 6–16) water molecules: a structure modeling

The structures of crystalline hydrates of calix[4]arene-para-sulfonic acid with n (n = 6–16) water molecules and the activation barriers to surface proton migration were calculated within the framework of the density functional theory (DFT) using the PBE gradient-corrected functional, the "hard" basis set of projector-augmented waves (PAW), a corresponding pseudopotential, periodic boundary conditions, and the VASP program package. The energies of formation of crystalline hydrates from calix[4]arene-para-sulfonic acid and n water molecules calculated per water molecule are in the range of 0.4–0.9 eV and depend on n. The adsorption energy of water on the surface is in the range of 0.5–0.7 eV. The activation barriers to proton transfer across the surface calculated for the most stable crystal (n = 8) are close to experimental data and depend on the number of superstoihiometric water molecules, being equal to ~0.2 eV provided three superstoihiometric water molecules per surface SO₃H group.     

Conductivity of Lithium-Conducting Nafion Membranes Plasticized by Binary and Ternary Mixtures in the Sulfolan–Ethylene Carbonate–Diglyme System

Russian Journal of Electrochemistry - The electrotransport characteristics of the polymer electrolyte based on lithiated Nafion-115 membrane plasticized by high-boiling dipolar aprotic...