Mikio Ouchi

Bio: Mikio Ouchi is an academic researcher from Nankai University. The author has contributed to research in topics: Cation binding & Crown ether. The author has an hindex of 17, co-authored 58 publications receiving 953 citations.

Molecular design of crown ethers. 1. Effects of methylene chain length: 15- to 17-crown-5 and 18- to 22-crown-6

Abstract: Synthese des ethers crown et evaluation de leur aptitude a former des cations par extraction par solvant des picrates alcalins aqueux. La stabilite des complexes cation-ether crown est gouvernee par la variation d'enthalpie

Convenient and efficient tosylation of oligoethylene glycols and the related alcohols in tetrahydrofuran-water in the presence of sodium hydroxide

Abstract: Oligoethylene glycols and some related alcohols were efficiently tosylated with p-toluenesulfonyl chloride in a tetrahydrofuran–water (1:1) mixture in the presence of excess sodium hydroxide. This method is advantageous over the conventional tosylation in pyridine both regarding the work-up procedure, the yield, and the purity of the product, and may be potentially useful for the tosylation of certain acid-labile alcohols.

Molecular design of crown ethers. 4. Syntheses and selective cation binding of 16-crown-5 and 19-crown-6 lariats

Abstract: Les pouvoirs d'extraction des ethers lariat 16-crown-5 pour les cations mono- et divalents augmentent avec la longueur du bras oxyethylene lateral

Crown ethers of low symmetry. Spiro crown ethers and 16-crown-5 derivatives

Abstract: Synthese des spirocrowns; evaluation de leur aptitude a la coordination pour l'etude de l'extraction des picrates alcalins. Equilibres d'extraction. 16-crown-5 semble avoir une plus haute selectivite pour Na que 15-crown-5

Molecular Design of Crown Ethers. 3. Extraction of Alkaline Earth and Heavy Metal Picrates with 14- to 17-Crown-5 and 17- to 22-Crown-6

Abstract: The solvent extraction of alkaline earth and heavy metal picrates with a series of ring-contracted and ring-enlarged crown ethers has been carried out in order to reveal the effects of methylene-chain length upon cation-binding ability. Compared with the parent 3m-crown-m, the ring-contracted crown ethers and their sila analogues possess limited extractabilities, often as low as those for the corresponding glymes. On the other hand, the ring-enlarged crown ethers, in general, show gradual, but not drastic, decreases in extractability for most cations with increasing methylene-chain length. Interestingly, the extractabilities for Ag+, Tl+, and Ba2+ do not decrease monotonously with ring expansion; in particular 16-crown-5 is a better extractant for Ag+ than 15-crown-5 and even than 18-crown-6. These results are accounted for in terms of cavity size, conformation, and molecular symmetry of crown ethers. Effects of cation hydration upon extractability and the limitations of solvent extraction technique are a...

Stability and kinetics of G-quadruplex structures

Abstract: In this review, we give an overview of recent literature on the structure and stability of unimolecular G-rich quadruplex structures that are relevant to drug design and for in vivo function The unifying theme in this review is energetics The thermodynamic stability of quadruplexes has not been studied in the same detail as DNA and RNA duplexes, and there are important differences in the balance of forces between these classes of folded oligonucleotides We provide an overview of the principles of stability and where available the experimental data that report on these principles Significant gaps in the literature have been identified, that should be filled by a systematic study of well-defined quadruplexes not only to provide the basic understanding of stability both for design purposes, but also as it relates to in vivo occurrence of quadruplexes Techniques that are commonly applied to the determination of the structure, stability and folding are discussed in terms of information content and limitations Quadruplex structures fold and unfold comparatively slowly, and DNA unwinding events associated with transcription and replication may be operating far from equilibrium The kinetics of formation and resolution of quadruplexes, and methodologies are discussed in the context of stability and their possible biological occurrence

Ether- and Alcohol-Functionalized Task-Specific Ionic Liquids: Attractive Properties and Applications

Abstract: In recent years, the designer nature of ionic liquids (ILs) has driven their exploration and exploitation in countless fields among the physical and chemical sciences. A fair measure of the tremendous attention placed on these fluids has been attributed to their inherent designer nature. And yet, there are relatively few examples of reviews that emphasize this vital aspect in an exhaustive or meaningful way. In this critical review, we systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity (e.g. hydrophilicity, hydrogen bonding capability). In the latter portions of this review, we emphasize the attractive applications of these functionalized ILs across a range of disciplines, including their use as electrolytes or functional fluids for electrochemistry, extractions, biphasic systems, gas separations, carbon capture, carbohydrate dissolution (particularly, the (ligno)celluloses), polymer chemistry, antimicrobial and antielectrostatic agents, organic synthesis, biomolecular stabilization and activation, and nanoscience. Finally, this review discusses anion-functionalized ILs, including sulfur- and oxygen-functionalized analogs, as well as choline-based deep eutectic solvents (DESs), an emerging class of fluids which can be sensibly categorized as semi-molecular cousins to the IL. Finally, the toxicity and biodegradability of ether- and alcohol-functionalized ILs are discussed and cautiously evaluated in light of recent reports. By carefully summarizing literature examples on the properties and applications of oxy-functional designer ILs up till now, it is our intent that this review offers a barometer for gauging future advances in the field as well as a trigger to spur further contemplation of these seemingly inexhaustible and—relative to their potential—virtually untouched fluids. It is abundantly clear that these remarkable fluidic materials are here to stay, just as certain design rules are slowly beginning to emerge. However, in fairness, serendipity also still plays an undeniable role, highlighting the need for both expanded in silico studies and a beacon to attract bright, young researchers to the field (406 references).

Enhanced CO2 separation selectivity in oligo(ethylene glycol) functionalized room-temperature ionic liquids

Abstract: Novel imidazolium-based room-temperature ionic liquids (RTILs) with one, two, or three oligo(ethylene glycol) substituents were synthesized. Solubilities and ideal solubility selectivities of CO2, N2, and CH4 at low pressure (1 atm) in these RTILs were determined using a pressure decay technique. Comparison to corresponding alkyl analogues of these RTILs reveals similar levels of CO2 solubility but lower solubilities of N2 and CH4. As a consequence, RTILs with oligo(ethylene glycol) substituents were observed to have 30−75% higher ideal solubility selectivities for CO2/N2 and CO2/CH4.