Non-covalent interactions in bmimCl/co-solvent mixtures: A FTIR spectroscopy and computational study

Publication date: Available online 19 April 2019Source: Journal of Molecular LiquidsAuthor(s): Nikolay Kotov, Vladimír Raus, Jiří DybalAbstractIonic liquids such as 1-butyl-3-methylimidazolium chloride (bmimCl) are efficient solvents for cellulose, but high viscosity of the resulting solutions hampers further cellulose shaping and derivatization. To solve this problem, mixtures of ILs with various organic co-solvents are often employed in place of neat ILs. So far, the intermolecular interactions in such mixtures are poorly understood, which hinders further development of this class of cellulose solvents. In this work, we utilized infrared spectroscopy (IR) and quantum chemical model calculations to study the intermolecular interactions in differently concentrated mixtures of bmimCl with two typical co-solvents, dimethyl sulfoxide (DMSO) and N,N-dimethylacetamide (DMAc). First, we refined the assignment of the relevant characteristic bands in the IR spectra of the individual mixture components. This then helped us to reveal that bmim+-DMSO and bmim+-DMAc associates, stabilized by hydrogen bonds between the imidazolium ring CH groups and oxygens of DMSO or DMAc, are formed in the studied mixtures. Importantly, only a relatively small fraction of co-solvent molecules (up to ca. 20 mol% for DMSO and ca. 45 mol% for DMAc) are involved in the associate formation, leaving a large proportion of bmimCl molecules non-solvated. While the maximum co-solvent concentration at which...
Source: Journal of Molecular Liquids - Category: Molecular Biology Source Type: research