Structures of NADES Sample Clauses

Structures of NADES. Nuclear magnetic resonance (NMR) spectroscopy was applied to NADES in search for molecular interactions involved in this phenomenon. To start with, the existence of hydrogen bonds in these NADES was observed. Abbott et al. (2003) observed a cross-correlation between the fluoride ion from choline fluoride and protons from urea using heteronuclear Overhauser spectroscopy (HOESY). Also, Mele et al. (2003) observed a direct intermolecular and intramolecular interaction between 1-n-butyl-3-methylimidazolium tetrafluoroborate molecules through 1H-1H-nuclear overhauser spectroscopy (NOESY). In our study, for example, the HOESY spectrum of 1,2-propanediol- choline chloride-H2O (PCH) revealed a signal corresponding to the proton on the methyl group of 1,2-propanediol interacting with both the methyl carbon and methylene (connected to nitrogen) carbon of choline chloride. This implies that the protons of the hydroxyl group of 1,2-propanediol may form a hydrogen bond with choline chloride (Fig. 2a). The NOESY spectrum of PCH shows strong interaction between the protons on the hydroxyl groups from choline chloride, 1,2-propanediol, and water (Fig. 2b), implying that hydrogen bonds are formed between these hydroxyl groups. This example suggests that water might also participate in the supermolecular structure of NADES. A similar interaction was observed in other combinations, such as proline-malic acid- water (PMH) (Fig. 3). 1,2propanediol a) 11′ 3′ N+ Cl- 3’ CH3 2’ OH HO HO 1’ H2O 1 2 choline chloride HOESY correlation NOESY correlation 3′ 1′1 2′ 1OH