Influence of Hydration on the Structure and Interactions of Ethaline Deep-Eutectic Solvent: A Spectroscopic and Computational Study |
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| Authors: | Payam Kalhor Yan-Zhen Zheng Hamad Ashraf Bobo Cao Prof. Zhi-Wu Yu |
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| Affiliation: | 1. MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084 China;2. College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002 China |
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| Abstract: | Deep-eutectic solvents (DESs) are regarded as alternative green solvents to ionic liquids. In this work we report the structural properties and hydrogen bonding (H-bonding) interactions of an aqueous DES system. The used DES, ethaline (ETH), is composed of choline chloride and ethylene glycol (EG) in 1 : 2 molar ratio. The investigations were carried out by FTIR spectroscopy combined with quantum chemical calculations. Excess spectroscopy and two-dimensional correlation spectroscopy (2D-COS) were used to explore the data in detail. The results showed that, upon mixing, ETH transforms to EG dimers and trimers and D2O clusters transform to various ETH-D2O complexes. Theoretical calculations show that water molecules insert between the anion and cation of ETH, break the strong doubly ionic Cl− … H−OCh+ H-bond, share charges of the ions and form H-bond with them, thus modulate the interaction properties of ETH. This study deepens our molecular-level understanding of the system and would shed light on its applications. |
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| Keywords: | deep-eutectic solvent excess spectroscopy hydrogen bond quantum chemical calculation two-dimensional correlation spectroscopy |
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