Rikukawa Masahiro

In recent years, the development of next-generation secondary batteries employing resource-abundant metals such as Na has garnered significant attention. However, the high reactivity of Na raises safety concerns, necessitating the development of safer devices. To address this, ionic liquids (ILs) and organic ionic plastic crystals (OIPCs) have emerged as promising novel electrolytes. Despite their potential, studies investigating the influence of cation structures on various properties remain scarce, particularly in composites where Na salts are introduced into OIPCs. This study focuses on the effects of cation species and Na-salt concentration in OIPCs, specifically in N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide ([C2epyr][FSA]) and N-ethyl-N-isopropylpyrrolidinium bis(fluorosulfonyl)amide ([Ci3epyr][FSA]), with the addition of sodium bis(fluorosulfonyl)amide (NaFSA). The phase transition behavior, dissociation state of Na salts, and electrochemical properties exhibited significant differences based on the cationic structure of the OIPCs. The combination of each OIPC with Na salt resulted in liquid mixtures, and the ionic conductivity increased significantly as the Na salt concentration increased. High ionic conductivities were achieved with [C2epyr][FSA]/NaFSA (20 mol%) and [Ci3epyr][FSA]/NaFSA (10 mol%), showing values of 2.7 x 10-3 and 2.2 x 10-3 S cm-1 at 25 degrees C, respectively. Linear sweep voltammetry results indicated superior oxidative stability in the [Ci3epyr][FSA] system. Solvation numbers of Na+, influenced by differences in cationic side-chain structures, were determined to be 2.7 for the [C2epyr]+ system and 2.9 for the [Ci3epyr]+ system. The results suggest that controlling solvation numbers is a critical factor in the molecular design of high-performance ionic conductors.

Background: Developing environmentally benign processes, such as organic reactionsconducted in water, is desired from the view of sustainable technology. Concerning the palladiumcatalyzedborylation reactions of aryl halides in water, only a few examples have been reported. Objective: This study aimed to develop efficient methods for palladium-catalyzed borylation reactionsof aryl halides in water, not only increasing product yields but also extracting products withless organic solvents. Methods: We adopted polymer surfactants, such as diblock copolymers that consist of poly(Nisopropoylacrylamide)and a hydrophilic segment, and a poly(ethylene glycol)-based polymer thatconsists of poly(ethylene glycol) chain and 4-chloromethylbenzyl moiety. Results: Reactions using these polymers gave the borylation products in significantly higher yieldsthan that in pure water. The efficiency of the extraction process for the products from the reactionmixtures was evaluated, indicating that the polymer micelles enabled separation processes with lessorganic solvent. Conclusion: Applying polymer surfactants increased the product yields in Pd-catalyzed borylationof aryl halides, and it enabled the extraction of the products from the aqueous reaction mixture moreefficiently.

Pd complexes covalently tethered on thermoresponsive polymer catalysed coupling reactions in water.

Despite being safe for use in secondary Mg batteries, solid electrolytes exhibit lower ionic conductivities than those of traditional liquid electrolytes. Organic ionic plastic crystals-soft crystals with excellent thermal and electrochemical stabilities and ionic conductivities-are promising solid electrolytes. Herein, we investigated the effects of various anion species and Mg salt concentrations on the properties of pyrrolidinium-based organic ionic plastic crystals (N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide [[C2epyr][FSA]] and N,N-diethylpyrrolidinium bis(trifluoromethylsulfonyl)amide [[C2epyr][TFSA]]) upon Mg(TFSA)2 addition. The Mg-ion transference number (tMg2+) was measured using the Vincent-Bruce method; ionic conductivity via impedance measurements; and phase transition via differential scanning calorimetry. The phase transition behavior, dissociation state of the Mg salt, and electrochemical properties varied with the organic ionic plastic crystal anionic structure. The FSA system became liquid when the Mg salt concentration exceeded 15 mol%. The ionic conductivity of the pyrrolidinium-based organic ionic plastic crystals increased substantially with the Mg salt concentration. In the solid state, [C2epyr][FSA]/Mg(TFSA)2 (5 mol%) (FT5) showed the highest ionic conductivity (2.9 × 10−4 S cm−1 at 25 °C). The tMg2+ of FT5 at 60 °C was 0.29. Mg exhibited redox behavior in FT5 but not in [C2epyr][TFSA]/Mg(TFSA)2 (5 mol%). The FSA− structure is suitable for Mg electrochemistry and will aid in developing high-performance secondary Mg batteries.