Dynamics of Polar Solvation in Quaternary Microemulsions

Abstract

Steady-state spectroscopy and time-resolved solvation dynamics have been used to investigate the effects the addition of alkanol has on the location of coumarin 343 (C343) in cetyltrimethylammonium bromide (CTAB)/1-pentanol/cyclohexane/water, CTAB/1-heptanol/cyclohexane/water, and sodium dodecyl sulfate/1-heptanol/cyclohexane/water reverse micelles. Steady-state spectroscopy showed that the probe molecule is not sensitive to alkanol chain lengths or water loading. Instead, C343 is sensitive to the surfactant used to form the reverse micelles. Solvation dynamics measurements utilizing ultrafast time-resolved fluorescence-upconversion spectroscopy revealed two solvation reorganization times regardless of the micellar system studied or hydration level. A hundreds of picosecond time component is attributed to collective motion of the interface. Time-zero analysis reveals a substantial relaxation component occurring on the femtosecond time scale.

Probing the Interior of Self-Assembled Caffeine Dimer at Various Temperatures

“…All these time scales are however, faster than those observed for caffeine solutions even at elevated temperature confirming the structured nature of the hydrated water molecules in caffeine solution with respect to an ionic solution. On the other hand these time scales are rather comparable [47] or faster [48] in reverse micelles or micelles [35] confirming our finding that caffeine is aggregated as dimers in aqueous solution and with a rather weakly structured water network around it. The smaller inset inside Fig.…”

Solvation dynamics of coumarin 480 in neutral (TX-100), anionic (SDS), and cationic (CTAB) water-in-oil microemulsions

“…In this Letter, we would like to characterize TX-100/cyclohexane/1-hexanol/water, SDS/1-hexanol/water, and CTAB/isooctane/1-hexanol/water w/o microemulsions with the help of steady state and time resolved emission spectroscopy as well as like to measure the solvation dynamics in the above three microemulsions using Coumarin 480 (C-480, Scheme 1) as a probe. Unlike Corbeil and Levinger [23], here we have reported the slow solvation dynamics in alkane/1-hexanol mixture compared to pure 1-hexanol. Moreover, we would also like to verify the role of ionic solvation in the solvation dynamics in these microemulsions.…”

“…Though there are lots of solvation dynamics studies in AOT reverse micelle [21,22,25,26], but such studies in quaternary microemulsions are lagging behind. Very recently, Corbeil and Levinger [23] have reported slow solvation dynamics in quaternary microemulsions of SDS and CTAB using Coumarin 343 (C-343) as a probe. Curiously, they have ignored the rather dramatic retardation of solvation dynamics in alkane/alkanol mixture itself.…”

Solvent relaxation of a room-temperature ionic liquid [bmim][PF6] confined in a ternary microemulsion

“…It is due to the fact with increase in w value the dye molecules migrate towards the polar solvent pool of the microemulsions and the size of the microemulsions also increases, so that mobility of the solvent in the microemulsion pool increases, which leads to decrease in solvent-relaxation time. In some cases where the probe molecule resides at the surface of the microemulsion, solvent-relaxation time is practically unaltered with change in w value 61,62. This result, i.e.…”