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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.)

Phase Transitions of the Ionic Liquid [C(2)C(1)im][NTf2] under High Pressure: A Synchrotron X-ray Diffraction and Raman Microscopy Study

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Faria, Luiz F. O. [1] ; Lima, Thamires A. [1] ; Ribeiro, Mauro C. C. [1]
Total Authors: 3
[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Lab Espect Mol, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Crystal Growth & Design; v. 17, n. 10, p. 5384-5392, OCT 2017.
Web of Science Citations: 9

The interplay between crystallization and glass transition in the archetypal ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide, {[}C(2)C(1)im]{[}NTf2], has been studied as a function of pressure up to ca. 12 GPa. Besides heterogeneous crystal nucleation, homogeneous nucleation in the sample inside the diamond anvil cell was also observed depending on compression/decompression rate. Amorphization of the crystal and glass formation under pressure has been followed by synchrotron X-ray diffraction. The characteristic Raman bands of the {[}NTf2](-) anion provide a microscopic probe of the different phases. The crystalline phase is composed of the {[}NTf2](-) cisoid conformer, but moisture implies formation of crystal with the transoid conformer. Raman spectra show that crystalline phases might become microscopically heterogeneous because of {[}NTf2](-) conformational disorder. Raman mapping reveals the order disorder evolution from crystal to glass. Crystals of {[}C(2)C(1)im]{[}NTf2] formed under high pressure and room temperature are similar to previously reported low temperature and atmospheric pressure crystals. Thus, it is concluded that density is the main factor controlling crystallization and glass formation under high pressure of {[}NTf2](-) based ionic liquids due to hindrance of efficient ion packing. The results highlight that ionic liquids are good models to understand fundamental questions related to the mechanism of crystallization and glass transition. (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