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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Ultraslow Phase Transitions in an Anion-Anion Hydrogen-Bonded Ionic Liquid

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Faria, Luiz F. O. [1] ; Lima, Thamires A. [1] ; Ferreira, Fabio F. [2] ; Ribeiro, Mauro C. C. [1]
Total Authors: 4
[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Lab Espect Mol, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil
[2] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210580 Santo Andre, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of Physical Chemistry B; v. 122, n. 6, p. 1972-1980, FEB 15 2018.
Web of Science Citations: 5

A Raman spectroscopy study of 1-ethyl-3-methylimidazolium hydrogen sulfate, {[}C(2)C(1)im]{[}HSO4], as a function of temperature, has been performed to reveal the role played by anion-anion hydrogen bond on the phase transitions of this ionic liquid. Anion-anion hydrogen bonding implies high viscosity, good glass forming ability, and also moderate fragility of {[}C(2)C(1)im]{[}HSO4] in comparison with other ionic liquids. Heating {[}C(2)C(1)im]{[}HSO4] from the glassy phase results in cold crystallization at similar to 245 K. A solid-solid transition (crystal I -> crystal II) is barely discernible in calorimetric measurements at typical heating rates, but it is clearly revealed by Raman spectroscopy and X-ray diffraction. Raman spectroscopy indicates that crystal I has extended ({[}HSO4](-))(n) chains of hydrogen-bonded anions but crystal II has not. Raman spectra recorded at isothermal condition show the ultraslow dynamics of cold crystallization, solid-solid transition, and continuous melting of {[}C(2)C(1)im]{[}HSO4]. A brief comparison is also provided between {[}C(2)C(1)im]{[}HSO4] and {[}C(4)C(1)im]{[}HSO4], as Raman spectroscopy shows that the latter does not form the crystalline phase with extended anion-anion chains. (AU)

FAPESP's process: 15/05803-0 - Ionic liquid structure under high pressure
Grantee:Luiz Felipe de Oliveira Faria
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 12/13119-3 - Vibrational spectroscopy in condensed phases
Grantee:Mauro Carlos Costa Ribeiro
Support type: Research Projects - Thematic Grants
FAPESP's process: 14/15049-8 - A Raman spectroscopy study of the glass transition of ionic liquids under high pressure.
Grantee:Thamires Andrade Lima
Support type: Scholarships in Brazil - Post-Doctorate