Toward a new type of proton conductor based on imidazole and aromatic acids.

A new approach towards achieving proton conducting materials based on aromatic acids and heterocyclic bases was proposed. It can lead to a new material in which all hydrogen bonding interactions are of medium or weak strength and rotations of the base and acid molecules are possible. If the above conditions are met, one can expect a high value of proton conductivity governed by the Grotthuss mechanism. Two salts of imidazole, one with benzoic acid having one carboxylic acid group and another with salicylic acid having a carboxylic and hydroxyl group located in the ortho position, were synthesized. Physical properties of these newly synthesized proton conducting salts were investigated using experimental and theoretical methods. The structures of these salts were studied by X-ray diffraction and 1H and 13C NMR techniques. The intermolecular interactions in the salts were analyzed by DFT calculations, within the QTAiM theory, and by Hirshfeld surface analysis. The π-π interactions, the proton conduction pathways, and the transport mechanism are also discussed.

Spectroscopic and quantum chemical studies of interaction between the alginic acid and Fe3O4 nanoparticles.

In this work, we present the spectral investigation of the interactions between the coverage with alginic acid (AA) and nanoparticles for three different composites containing 74, 80, and 88wt% of magnetite. These results show that the Fe3O4 nanoparticles are coated with the AA and indicate that there is an interaction between them. Moreover, we have investigated the thermal and magnetic properties of all investigated compounds. We show that bonding of alginic acid to the surface of magnetite results in better thermal stability of the polymer and in higher temperature of AA chains degradation. We find that for dense assembly of magnetite nanoparticles, at low temperatures, the intergranular coupling becomes much stronger than between nanoparticles dispersed in composites.

Proton conducting system (ImH2)2SeO4·2H2O investigated with vibrational spectroscopy.

Imidazolium selenate dihydrate (ImH2)2SeO4·2H2O crystals have been investigated using Raman and IR spectroscopy. Experimental data were supported by the quantum-chemical calculations (DFT), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. The imidazolium selenate dihydrate crystal exhibits high proton conductivity of the order of ~10-1S/m at T=333K. The spectra of this compound are dominated by bands related to the lattice modes, the internal vibrations of the protonated imidazole cation, selenate anion, water molecules, and hydrogen bonds network. For the imidazolium selenate dihydrate crystal, the formal classification of the fundamental modes has been carried out.

Lattice dynamics through the structural phase transition in D-amphetamine sulfate.

The polarized infrared and Raman spectra of the single-crystalline D-amphetamine sulfate have been measured as a function of temperature in the vicinity of the structural phase transition. Infrared and Raman-active modes are identified and assigned. Significant signatures of the structural phase transition are observed in the temperature dependence of infrared modes both of the D-amphetamine unit and the sulfate anion. The changes reflect differences in the unit cell between low- and high-temperature phases of the D-amphetamine sulfate. Temperature dependence of the vibrational mode parameters displays pronounced hysteresis between 333 and 338 K that is extended over a smaller temperature range than 325-345 K found in the earlier DSC study.

Morphology, molecular dynamics and electric conductivity of carbohydrate polymer films based on alginic acid and benzimidazole.

The present paper describes a preparation method and molecular investigations of new biodegradable proton-conducting carbohydrate polymer films based on alginic acid and benzimidazole. Electric conductivity was studied in a wide temperature range in order to check the potential application of these compounds as membranes for electrochemical devices. Compared to pure alginic acid powder or its film, the biodegradable film of alginic acid with an addition of benzimidazole exhibits considerably higher conductivity in the range above water boiling temperature (up to approximately 10(-3) S/cm at 473 K). Due to this important feature the obtained films can be considered as candidates for application in high-temperature electrochemical devices. The microscopic nature and mechanism of the conduction in alginate based materials were studied by proton nuclear magnetic resonance (NMR). The results show specific changes in morphology and molecular dynamics between pure alginate powders and the films obtained without and with the addition of benzimidazole molecules.