Dynamic Solvation in Phosphonium Ionic Liquids:  Comparison of Bulk and Micellar Systems and Considerations for the Construction of the Solvation Correlation Function, C(t)

Abstract

Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid: hexadecyltributylphosphonium bromide, [(C4)3C16P+][Br-]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725−10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the "zero-time" spectrum is constructed. Arlington, Box 19065, Arlington, Texas 76019 ReceiVed: NoVember 8, 2007; In Final Form: December 7, 2007 Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid: hexadecyltributylphosphonium bromide, [(C 4 ) 3 C 16 P + ][Br -]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725-10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the "zero-time" spectrum is constructed. Keywords

Density, viscosity and excess properties in the trihexyltetradecylphosphonium chloride ionic liquid/methanol cosolvent system

“…It is often the case that added solvent results in a simple decrease of IL viscosity through the disruption of IL ion pair association. But in some cases, such as with added water, the solution structure can even result in the formation of micellar structures [59,64]. In only one of these reports was the goal to characterize any excess solution property.…”

Structure and Dynamics of the 1-Hydroxyethyl-4-amino-1,2,4-triazolium Nitrate High-Energy Ionic Liquid System

“…ν(∞) is (usually 65,66 ) the frequency at infinite time, obtained from the maximum of the steady state spectrum. (This is not, however, true in the case of very slowly relaxing solvents, as has been demonstrated in the The Journal of Physical Chemistry B ARTICLE case of certain ionic liquids, 11,65,66 for which the emission spectrum at ∼3 times the fluorescence lifetime of the probe is red-shifted to that of the equilibrium spectrum.) The ν(t) values are determined from the maxima of the log-normal fits of the timeresolved emission spectra.…”

“…23,58 The specific synthesis of 1-hydroxyethyl-4-amino-1,2,4-triazolium bromide (HEATB) and 1-hydroxyethyl-4-amino-1,2,4-triazolium nitrate (HEATN) from metathesis of HEATB with silver nitrate follows the procedure described by Drake, Hawkins, and Tollison. 59 The synthesis of the other ionic liquids shown in Figure 1 is described elsewhere, 11,60,61 and they were decolorized according to the procedure described previously. 62 Briefly, the impure ionic liquid was diluted and was allowed to elute through a column packed with celite, silica gel, and activated charcoal.…”

Nanosecond, Time-Resolved Shift of the Photoluminescence Spectra of Organic, Lead-Halide Perovskites Reveals Structural Features Resulting from Excess Organic Ammonium Halide

“…We do not consider earlier-time dynamics, and we do not normalize the shifts. Equation (1) is formally identical to the "solvation correlation function," C(t), which has been applied to the dynamic spectral shifts (transient Stokes shifts) 39,40,41 of organic fluorophores in polar solvents.…”