title: Unraveling the Stepwise Melting of an Ionic Liquid.
abstract: Differential scanning calorimetry, X-ray diffraction, and Raman spectroscopy were used to reveal the premelting events precursors of melting of the ionic liquid triethylsulfonium bis(trifluoromethanesufonyl)imide, [S222][NTf2]. On heating the crystalline phase of [S222][NTf2], melting occurs along a sequence of at least three steps. First, the crystalline long-range order breaks down, but local order is retained. The second step is characterized by conformational freedom of the ethyl chains of cations related to premelting of nonpolar domains, and the complete melting finally occurs when anions acquire conformational freedom. This work provides a microscopic view on the mechanism of melting of [S222][NTf2] in line with the picture of melting taking place as a sequence of structural changes. The results of this work shed light on the understanding of the complex melting process of ionic liquids.
authors.affiliation: Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil.
authors.forename: Thamires A
authors.initials: TA
authors.lastname: Lima
authors.affiliation: Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil.
authors.forename: Vitor H
authors.identifier: 0000-0002-0935-3772
authors.initials: VH
authors.lastname: Paschoal
authors.affiliation: Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil.
authors.forename: Luiz F O
authors.identifier: 0000-0002-0711-4604
authors.initials: LFO
authors.lastname: Faria
authors.affiliation: Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil.
authors.forename: Mauro C C
authors.identifier: 0000-0002-4301-5021
authors.initials: MCC
authors.lastname: Ribeiro