Abstract
Dielec. and solvation data on mixts. of 1-butyl-3-methylimidazolium tetrafluoroborate ([Im41][BF4]) + water are reported and used to examine the utility of dielec. solvation models. Dielec. permittivity and loss spectra (25 °C) were recorded over the frequency range 200 MHz to 89 GHz at 17 compns. and fit to a 4-Debye form. Dynamic Stokes shift measurements on the solute coumarin 153 (C153), ...
Abstract
Dielec. and solvation data on mixts. of 1-butyl-3-methylimidazolium tetrafluoroborate ([Im41][BF4]) + water are reported and used to examine the utility of dielec. solvation models. Dielec. permittivity and loss spectra (25 °C) were recorded over the frequency range 200 MHz to 89 GHz at 17 compns. and fit to a 4-Debye form. Dynamic Stokes shift measurements on the solute coumarin 153 (C153), made by combining fluorescence upconversion (80 fs resoln.) and time-correlated single photon counting data (20 ns range), were used to det. the solvation response at 7 compns. (20.5 °C). All properties measured here were found to depend upon mixt. compn. in a simple continuous manner, esp. when viewed in terms of vol. fraction. Solvation response functions predicted by a simple dielec. continuum model are similar to but ~7-fold faster than the spectral response functions measured with C153. The solvation data are in better agreement with the recently published predictions of a semimol. model of Biswas and co-workers, but these latter predictions are systematically slow by a factor of ~3.
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