Hydrogen fluoride capture by imidazolium acetate ionic liquid

Self-healing in dielectric capacitors: a universal method to computationally rate newly introduced energy storage designs

Metalized-film dielectric capacitors provide lump portions of energy on demand. While the capacities of various capacitor designs are comparable in magnitude, their stabilities make a difference. Dielectric breakdowns - micro-discharges - routinely occur in capacitors due to the inevitable presence of localized structure defects. The application of polymeric dielectric materials featuring flexible structures helps obtain more uniform insulating layers. At the modern technological level, it is impossible to completely avoid micro-discharges upon device exploitation. Every micro-discharge results in the formation of a soot channel, which is empirically known to exhibit a semiconductor behavior. Because of its capability to conduct electricity, the emerged soot channels harm the subsequent capacitor performance and decrease the amount of stored energy. The accumulation of the soot throughout a dielectric capacitor ultimately results in irreversible overall failure. We have developed a universal method for predicting the composition and evaluating the properties of the decomposition products obtained after the dielectric breakdown of a metalized film capacitor. This method applies to both existing and newly developed designs of capacitors. In our work, we compared samples based on polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), and Kapton. We found that the decomposition of the PP-based composition yields the greatest number of gaseous products. The corresponding soot has the lowest electrical conductivity compared to other samples. The smallest fraction of gaseous products and the highest conductivity corresponded to the Kapton-based system. According to the electrical conductivity, the obtained soot samples have been ranked in the following order: PP < PET < PC < Kapton. The resulting gas phase content is as follows: PP (12.3 wt%) > PC (6.4 wt%) > PET (6.2 wt%) > Kapton (5.1 wt%). The obtained results are in agreement with the experimental data on the self-healing efficiency of metalized-film capacitors. The novel method qualitatively correctly rates the performances of the known capacitors. The method relies on various electronic-structure simulations and potential landscape explorations. The reported advances open an impressive avenue to computationally probe thousands of hypothetical capacitor designs and boost engineering practices.

Achieving regio- and stereo-control in the fluorination of aziridines under acidic conditions

We developed an efficient fluorination protocol that converts easily accessible aziridines into β-fluoroamines, which are important motifs in biologically active molecules. In contrast with traditional fluorination approaches, DMPU-HF has shown both higher reactivity and regioselectivity and good functional group tolerance; thus, a wide scope of β-fluoroamines can now be accessed conveniently. The stereochemical behavior of the ring opening depends on the substitution pattern of the aziridine substrate.

Enhanced stability of the model mini-protein in amino acid ionic liquids and their aqueous solutions

Using molecular dynamics simulations, the structure of model mini-protein was thoroughly characterized in the imidazolium-based amino acid ionic liquids and their aqueous solutions. Complete substitution of water by organic cations and anions further results in hindered conformational flexibility of the mini-protein. This observation suggests that amino acid-based ionic liquids are able to defend proteins from thermally induced denaturation. We show by means of radial distributions that the mini-protein is efficiently solvated by both solvents due to a good mutual miscibility. Amino acid-based anions prevail in the first coordination sphere of positively charged sites of the mini-protein whereas water molecules prevail in the first coordination sphere of negatively charged sites of the mini-protein.