Netsu Sokutei
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
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Preface
Special Issue - Trends in Thermodynamics of Solutions -
  • Forword for Special Issue
    Ryou Kanzaki
    2024 Volume 51 Issue 1 Pages 2
    Published: January 25, 2024
    Released on J-STAGE: February 27, 2024
    DOIhttps://doi.org/10.11311/jscta.51.1_2
    JOURNAL RESTRICTED ACCESS
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  • Superior Electrically Conductive Deep Eutectic Solvents Containing Iodine and Attempt for Their Calorimetry Measurement
    Hideaki Shirota, Koyakkat Maharoof, Shingo Yajima, Junpei Sato, Katsuh ...
    2024 Volume 51 Issue 1 Pages 3-9
    Published: January 25, 2024
    Released on J-STAGE: February 27, 2024
    DOIhttps://doi.org/10.11311/jscta.51.1_3
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    Deep eutectic solvents (DESs) are liquid-state mixtures, which mostly consist of two or more solid compounds, at room temperature because of the strong eutectic effect. After discovering a liquid-state mixture of choline chloride and urea (1:2 in molar ratio) at room temperature as DES in 2003, DESs have gotten more attention recently as a new type of solvent. In this review, we introduce unique DESs consisting of an organic iodide salt, e.g., 1-alkyl-3-methylimidazolium iodides and ammonium iodides, and iodine. The DESs of an organic iodide salt and iodine are easily prepared: just mixing two components. They show a very high electrical conductivity, typically more than 10 mS cm–1. For example, a 1:2.5 mixture of methylammonium iodide and iodine shows approximately 100 mS cm–1 at 298 K. Based on the viscosity and Raman spectrum, the superior electrical conductivity of the DESs is attributed to the Grotthuss mechanism. In this article, we also introduce our attempt for differential calorimetry measurements of the DESs, which possess corrosivity for a wide variety of metals, using a fluororesin-coated aluminum pan.
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  • Molecular Replacement to Fine-tune the Function of Deep Eutectic Solvents: Substituent Effects in Deep Eutectic Solvent Composed of Guanidine Hydrochloride and Urea
    Tatsuya Umecky
    2024 Volume 51 Issue 1 Pages 10-14
    Published: January 25, 2024
    Released on J-STAGE: February 27, 2024
    DOIhttps://doi.org/10.11311/jscta.51.1_10
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    Guanidinium cation and urea are often used as protein denaturants because of their strong hydrogen-bond ability. A deep eutectic solvent (DES) composed of guanidine hydrochloride (GuHCl, Tm = 458 K) and urea (U, Tm = 407 K) with a molar ratio of [U]/[GuHCl] = 2 is a liquid medium that has the potential to denature proteins and dissolve biomaterials. However, heating is essential when using 2U-GuHCl as a liquid solvent. This is because the eutectic temperature of this DES is 331 K, which is higher than room temperature. This heating is a serious problem when dissolving solutes with low thermal stability. We focused on two urea derivatives, N-methylurea (Um, Tm = 378 K) and N-hydroxyurea (Uh, Tm = 414 K), to obtain GuHCl-based DESs in liquid state at room temperature. Since all of the GuHCl-based DESs containing Um molecules were fluid at room temperature, the Um molecule is a candidate hydrogen bond donor for fluidizing GuHCl-based DESs. This paper presents experimental results of binary and ternary DESs composed of GuHCl, U, Um, and Uh. In addition, preparation methods for general DESs are outlined.
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  • Speciation and Dynamics of Super-concentrated Electrolyte Solution for Next-generation Secondary Battery
    Hikari Watanabe, Jihae Han, Yasuhiro Umebayashi
    2024 Volume 51 Issue 1 Pages 15-21
    Published: January 25, 2024
    Released on J-STAGE: February 27, 2024
    DOIhttps://doi.org/10.11311/jscta.51.1_15
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    Ionic liquids are composed only of ionic species and have been attracted attention as electrolytes for fuel cells and next-generation secondary batteries. Ionic liquids are often found to have the specific ionic conduction mechanism. We recently found that the equimolar mixtures of N-methylimidazole (C1Im) and acetic acid (CH3COOH) have significant ionic conductivity, although only electrically neutral molecules practically exist in their equimolar mixture. We propose such liquids can be called as the pseudo-protic ionic liquids pPILs and consider that the specific proton conduction without static acid dissociation may occur in the mixture. On the other hand, solvate ionic liquids have been proposed as electrolyte solution for lithium sulfur battery. In this study, we discuss on ionic conduction mechanism for the nonequimolar pPILs. In addition, we demonstrate in-situ impedance measurements to reveal ion dynamics in electrode/electrolyte interface for the battery using the solvate ionic liquid.
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  • Understanding the Dissolution Mechanism of Hydrophobic Dyes through Statistical Thermodynamics
    Yu Kanasaki
    2024 Volume 51 Issue 1 Pages 22-26
    Published: January 25, 2024
    Released on J-STAGE: February 27, 2024
    DOIhttps://doi.org/10.11311/jscta.51.1_22
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    Hydrophobic dyes are used in water with solubilizers. Hydrotrope is a solubilizer of low molecular weight, weakly amphiphilic organics. and is known to promote solubilization of drugs, dyes, and pigments. One of most famous hydrotropes, urea, serves as an efficient solubilizing agent for dyes. In this study, in order to elucidate the molecularlevel mechanisms responsible for urea's effectiveness as a solubilizer, we apply a statistical thermodynamics approach rooted in the Kirkwood-Buff theory of solutions. Our findings demonstrate two key insights: (i) in contrast to the traditional notion of " water structure disruption, " the impact of urea on dye hydration has a relatively minor role in the solubilization process; (ii) the primary driving force for solubilization arises from the accumulation of urea molecules surrounding hydrophobic dye molecules.
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