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Faria LFO, Paschoal VH, Lima TA, Ferreira FF, Freitas RS, Ribeiro MCC. Local Order-Disorder Transition Driving by Structural Heterogeneity in a Benzyl Functionalized Ionic Liquid. J Phys Chem B 2017; 121:9902-9909. [PMID: 28968103 DOI: 10.1021/acs.jpcb.7b08829] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A local order-disorder transition has been disclosed in the thermophysical behavior of the ionic liquid 1-benzyl-3-methylimidazolium dicyanamide, [Bzmim][N(CN)2], and its microscopic nature revealed by spectroscopic techniques. Differential scanning calorimetry and specific heat measurements show a thermal event of small enthalpy variation taking place in the range 250-260 K, which is not due to crystallization or melting. Molecular dynamic simulations and X-ray diffraction measurements have been used to discuss the segregation of domains in the liquid structure of [Bzmim][N(CN)2]. Raman and NMR spectroscopy measurements as a function of temperature indicate that the microscopic origin of the event observed in the calorimetric measurements comes from structural rearrangement involving the benzyl group. The results indicate that the characteristic structural heterogeneity allow for rearrangements within local domains implying the good glass-forming ability for the low viscosity ionic liquid [Bzmim][N(CN)2]. This work sheds light on our understanding of the microscopic origin behind complex thermal behavior of ionic liquids.
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Affiliation(s)
- Luiz F O Faria
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Avenida Prof. Lineu Prestes 748, 05508-000, São Paulo, São Paulo, Brazil
| | - Vitor H Paschoal
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Avenida Prof. Lineu Prestes 748, 05508-000, São Paulo, São Paulo, Brazil
| | - Thamires A Lima
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Avenida Prof. Lineu Prestes 748, 05508-000, São Paulo, São Paulo, Brazil
| | - Fabio F Ferreira
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC , 09210-580 Santo André, São Paulo, Brazil
| | - Rafael S Freitas
- Instituto de Física, Universidade de São Paulo , 05314-970 São Paulo, São Paulo, Brazil
| | - Mauro C C Ribeiro
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Avenida Prof. Lineu Prestes 748, 05508-000, São Paulo, São Paulo, Brazil
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Penna TC, Faria LFO, Matos JR, Ribeiro MCC. Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids. J Chem Phys 2013; 138:104503. [DOI: 10.1063/1.4793760] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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