The time-scale and site preferential interaction of CO2 absorption in tetra-butylphosphonium lysinate amino acid ionic liquid is examined using molecular dynamics simulations.

Sodium perchlorate (NaClO 4 ) crystallizes with adiponitrile (ADN) as a 1:3 solvate to produce (ADN) 3 NaClO 4 , a solid electrolyte for sodium ion conduction. The solid possesses high thermal stability (up to 150 °C) and the ability to be melt-cast (T m = 81 °C). The pressed solid has a high ionic conductivity of 2.2 × 10 −4 S cm −1 at room temperature with a low activation barrier for ion conduction of 22 kJ mol −1 . The high conductivity is the result of low-affinity ion-conduction channels in the bulk based on the X-ray crystal structure, and by low grain-boundary resistance and possibly a grain-boundary percolating network due to a fluidlike nanoliquid layer between the grains, observable by scanning electron microscopy and differential scanning calorimetry. When the liquid nanolayer is rinsed away or removed by excessive drying, the bulk room temperature ionic conductivity is 4 × 10 −5 S cm −1 , activation energy for ionic conduction for an organic solid is 37 kJ mol −1 , and the sodium ion transference number is 0.71. Scanning electron microscopy and classical molecular dynamics simulations suggest that these cocrystals form a fluid layer of ADN at the surface, which facilitates the Na + ion migration between the grains. Density functional theory calculations are consistent with the possibility of ion conduction via a solvent−anion coordinated transition state through vacancy defects in the three symmetry-equivalent ion channels along separate directions, suggesting the possibility of ionic conductivity in three dimensions.

Electron paramagnetic resonance (EPR) and optical absorption spectra of Mn2+ ions in alkali borotellurite glass systems have been studied. The EPR spectra of all the glass samples exhibit three resonance signals at g ≈ 2.0, g ≈ 3.3 and g ≈ 4.3. A six line hyperfine structure has also been observed at g ≈ 2.0. The concentration and temperature dependence of EPR signals were studied for Mn2+ ions in potassium borotellurite glass samples. The zero-field splitting parameter D has been calculated for different alkali borotellurite glass samples from the intensities of the allowed hyperfine lines. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/χ versus T graph. The optical absorption spectrum exhibits a single broad band near 498 nm and this has been attributed to the spin-allowed 5Eg → 5T2g transition of Mn3+ ions in octahedral symmetry. The optical band gap energy (E opt ) and Urbach energy (Δ E) were calculated from their ultraviolet edges. The optical band gap energy varies between 3.38 and 3.61 eV and increases from Li to K glasses.

The understanding of mechanism of reactions between the [Lys]− anion and CO2 is important for the optimization and design of salt mixtures and ionic liquids for facile CO2 capture. In this computational investigation, we employed density functional theory calculations to examine various reaction pathways associated with site-specific interactions possible in [Lys]−–CO2 and [Lys]−–H2O–CO2 complexes. The reaction mechanisms in each complex are characterized by energy parameters such as binding energy (BE), activation energy (E a), and reaction energy (RE). The [Lys]−–CO2 interactions lead to the formation of three nonbonded (NB) complexes close to the near-carboxylate amine group (N1) and one NB complex close to the far-carboxylate amine group (N2). The N1 site reacts with CO2 with a small barrier of ∼1 kcal/mol to form a stable “carbamate–carboxylic acid” product. The formation of this product is due to an intramolecular proton transfer from the N1 amine site to the carboxylate group (COO–), in contrast to the intermolecular proton transfer for carbamic acid formation observed from the N2–CO2 reaction. The other two NB complexes show significant stability due to multiple-site-cooperative interactions of CO2 with the COO– group and N1 site. In [Lys]−–H2O–CO2 interactions, nine NB complexes are formed corresponding to different weak interactions. Among them, five NB complexes lead to reactions suggesting chemisorption, with four complexes forming a direct bicarbonate product and the remaining complex forming a carbamate–carboxylic acid product. The other four nonreactive complexes show notable stability due to the formation of multiple hydrogen bonds with the inclusion of water, which alludes to their possibility of occurrence in physisorption.