Advisor(s)
Abstract(s)
There is a lack of fundamental knowledge on deep eutectic solvents, even for the most extensively
studied mixtures, such as the mixture of cholinium chloride and urea, which prevents a judicious choice
of components to prepare new solvents. The objective of this work is to study and understand the
fundamental interactions between cholinium chloride and urea that lead to the experimentally observed
melting temperature depression. To do so, the structure of urea was strategically and progressively
modified, in order to block certain interaction centres, and the solid–liquid equilibrium data of each
new binary system was experimentally measured. Using this approach, it was concluded that the most
important interaction between cholinium chloride and urea occurs through hydrogen bonding between
the chloride anion and the amine groups. Any blockage of these groups severely hampers the melting
point depression effect. Raman spectroscopy and DFT calculations were utilized to study in more detail
this hydrogen bonding and its nuances.
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Pedagogical Context
Citation
Silva, Liliana P.; Araújo, Catarina F.; Abranches, Dinis O.; Melle-Franco, Manuel; Martins, Mónia A.R.; Nolasco, Mariela M.; Ribeiro-Claro, Paulo J.A.; Pinho, Simão P.; Coutinho, João A.P. (2019). What a difference a methyl group makes-probing choline-urea molecular interactions through urea structure modification. Physical Chemistry Chemical Physics. ISSN 1463-9076. 21, p. 18278-18289