Abranches, Dinis O.Silva, Liliana P.Martins, Mónia A.R.Pinho, SimãoCoutinho, João A.P.2018-02-192021-02-272018-01-192021-02-272020Abranches, Dinis O.; Silva, Liliana P.; Martins, Mónia A.R.; Pinho, Simão P.; Coutinho, João A.P. (2020). Understanding the formation of deep eutectic solvents: betaine as a universal hydrogen bond acceptor. ChemSusChem. ISSN 1864-5631. 13:18, p. 4916-49211864-5631http://hdl.handle.net/10198/23380© 2020 Wiley-VCH GmbH The mechanism of formation of betaine-based deep eutectic solvents (DES) is presented for the first time. Due to its polarity unbalance, it was found that betaine displays strong negative deviations from ideality when mixed with a variety of different organic substances. These results pave the way for a comprehensive design of novel deep eutectic solvents. A connection to biologically relevant systems was made using betaine (osmolyte) and urea (protein denaturant), showing that these two compounds formed a DES, the molecular interactions of which were greatly enhanced in the presence of water.engGreen chemistryNatural deep eutectic solventsNon-idealityTrimethylglycineZwitterionsjournal article10.1002/cssc.202001331