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Solvent and rotational relaxation of coumarin 153 in a protic ionic liquid dimethylethanolammonium formate
Debabrata Seth1, Souravi Sarkar, Nilmoni Sarkar
1Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, WB, India.
Abstract:
The solvent relaxation and orientational dynamics of coumarin 153 (C-153) was investigated in N,N-dimethylethanolammonium formate (DAF) with a variation of temperature. DAF is a protic room-temperature ionic liquid, comprised of nonaromatic cations. Both solvent relaxation and orientational dynamics of C-153 in DAF are linearly well-correlated with the bulk viscosity at different temperatures. We optimized the geometry of DAF using quantum chemical calculations using density functional theory methods. The optimized structure of DAF shows a nonbonded interaction between cation and anion, which suggests that a hydrogen bond is formed between hydrogen atoms attached to the nitrogen atom of the cation with the oxygen atom of the anion in DAF.
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