The structure of the free liquid surface of three protic ionic liquids, ethylammonium nitrate (EAN), propylammonium nitrate (PAN), and ethylammonium formate (EAF), has been elucidated using X-ray reflectivity. The results show all three liquids have an extended interfacial region, spanning at least five ion pairs, which can be divided into two parts. Adjacent to the gas phase are aggregates consisting of multiple cations and anions. Below this are layers oriented parallel to the macroscopic surface that are alternately enriched and depleted in cation alkyl chains and polar domains of cation ammonium groups and their anions, gradually decaying to the isotropic sponge-like bulk structure. The most pronounced layering is observed for PAN, driven by strong solvophobic interactions, while reduced hydrogen bonding in EAF results in the least structured and least extensive interfacial region.
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http://dx.doi.org/10.1039/c1cp22351h | DOI Listing |
Cellulose (Lond)
December 2024
Department of Chemical Engineering, Imperial College London, South Kensington, Exhibition Road, London, SW7 2AZ UK.
Unlabelled: We report a simple procedure to produce carboxylated cellulose nanocrystals (CNCs) from grassy biomass () using a two-step approach consisting of biomass fractionation with a protic ionic liquid followed by oxidation of the resulting cellulose-rich pulps with HO. The impact of the fractionation severity on the composition, structure, size, thermal stability, crystallinity, and degree of polymerization of the CNCs was evaluated. It was found that fractionation severity had a large impact on the pulp purity and its reactivity during the oxidation stage.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Department of Applied Chemistry, Graduate School of Science and Engineering, Doshisha University, Kyotanabe, Kyoyo 610-0321, Japan.
Excited-state proton transfer (ESPT) reactions of 5-cyano-2-naphthol (5CN2) and 5,8-dicyano-2-naphthol (DCN2) were investigated in protic ionic liquids (PILs) composed of quaternary ammonium (NH) ( = 2, 4, or 8) and hexanoate (CHCOO) using time-resolved fluorescence spectroscopy. The effects of the number of alkyl carbons in the cation and the basicity of the anion on the reaction yield and dynamics were examined. In a series of [NH][CHCOO], fluorescence from the hydrogen-bonding complex (AHBX) of a proton-dissociated form (RO) with a solvent acid in the electronic excited state was observed between the fluorescence bands of an acidic form (ROH) and an anionic form (RO) as in the case of [NH][CFCOO] (Fujii et al.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Department of Chemistry, J. C. Bose University of Science and Technology, YMCA, Faridabad 121006, India.
Binary ionic melts formed by a protic ionic liquid (PIL) 1,2,4-triazolium methanesulfonate ([TAZ][MS]) dissolved in methanesulfonic acid are studied as non-stoichiometric electrolytes. The composition-driven structure-property relationship of methanesulfonic acid is explored at varying molar fraction ratios from 0/100 to 10/90, 20/80, and 30/70 by the addition of 1,2,4-triazolium methanesulfonate [TAZ][MS] IL. To unveil molecular characteristics of these mixtures of [TAZ][MS] PIL and CHSOH, we performed classical molecular dynamics simulations at varying temperatures from 293 to 303, 363, and 423 K.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, China.
As a predictive tool, quantum chemical calculations can be used to design protic ionic liquids (PILs) and predict the result. By adding anionic negative potential sites, two dual-functional PILs diethylenetriamine-barbituric acid [CHN][CHNO] and diethylenetriamine-ethylenolactonium [CHN][CHNO] were designed. The simulation results indicated that multisite absorption of anions and cations resulted in an expected absorption ratio exceeding 3:1 (mol CO:mol ILs).
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Hunan Provincial Key Laboratory of Chemical Power Sources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
This study presents the synthesis of a transparent, flexible gel polymer electrolyte (GPE) based on the protic ionic liquid BMImHSO and on polyvinyl alcohol (PVA) through solution casting and electrochemical evaluation in a 2.5 V symmetrical C/C electrical double-layer solid-state capacitor (EDLC). The freestanding GPE film exhibits high thermal stability (>300 °C), wide electrochemical windows (>2.
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