Vibrational spectral dynamics and ion-probe interactions of the hydrogen-bonded liquids in 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide

We investigate ion-probe interactions within the molecular liquid, examine dynamics, and interpret the vibrational spectral dynamics of the mixtures of ionic liquid, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIm][NTf2] with the probes of varying alkyl chain length - HOD, methanol-d4, ethanol-d6. Structural analysis depicts pronounced interactions of the oxygen atom of HOD with the corresponding anionic oxygen site rather than the hydrogen atom located at the two-position of the imidazolium ring. Our computed frequency distribution for each of the probes in IL exhibits similarity with the experimental linear FT-IR spectrum. We further performed the orientational anisotropy calculations; the ion reorientation plays a significant role in determining the transport properties in ILs. The results of rotational anisotropy of the O-D bond vector reflect the hydrogen bond length-scale fluctuations and collective reorientation associated with the complete structural reorganization of the probe modes. Our findings in this study agree well with the earlier experimental and simulation studies.

Automated summary

We investigate the interaction and dynamics of ion-probe within a molecular liquid and interpret the vibrational spectral dynamics of mixtures of ionic liquid with probes of varying alkyl chain length. Structural analysis shows pronounced interactions of the oxygen atom with the corresponding anionic oxygen site. Our computed frequency distribution exhibits similarity with the experimental linear FT-IR spectrum. The rotational anisotropy results reflect the hydrogen bond length-scale fluctuations and collective reorientation associated with the complete structural reorganization of the probe modes.