Cosurfactant Impact on Probe Molecule in Reverse Micelles

Corbeil, Elizabeth M.; Riter, Ruth E.; Levinger, Nancy E.

doi:10.1021/jp037276o

Cited by 48 publications

(57 citation statements)

References 62 publications

(147 reference statements)

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“…20 We conclude that the changes in the structural organization are small enough that the overall volume of the layer and the associated inner water pool do not change. The ability of HB and B − to become part of the interface is consistent with observations in other systems such as dipicolinic acid, 24,26 and a series of vanadium complexes, 41,46 but different from a charged compound such as metformin that is exclusively at the interface. 47 …”

Section: Resultssupporting

confidence: 87%

Differences in Interactions of Benzoic Acid and Benzoate with Interfaces

et al. 2016

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The interaction of benzoic acid and benzoate with model membrane systems was characterized to understand the molecular interactions of the two forms of a simple aromatic acid with the components of the membrane. The microemulsion system based on bis(2ethylhexyl)sulfosuccinate (AOT) allowed determination of the molecular positioning using 1D NMR and 2D NMR spectroscopic methods. Benzoic acid and benzoate were both found to penetrate the membrane/water interfaces; however, the benzoic acid was able to penetrate much deeper and thus is more readily able to traverse a membrane. The Langmuir monolayer model system, using dipalmitoylphosphatidylcholine, was used as a generic membrane lipid for a cell. Compression isotherms of monolayers demonstrated a pH dependent interaction with a lipid monolayer and confirming the pH dependent observations shown in the reverse micellar model system. These studies provide an explanation for the antimicrobial activity of benzoic acid while benzoate is inactive. Furthermore, these studies form the framework upon which we are investigating the mode of bacterial uptake of pyrazinoic acid, the active form of pyrazinamide, a front line drug used to combat tuberculosis.

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Section: Resultssupporting

confidence: 87%

Differences in Interactions of Benzoic Acid and Benzoate with Interfaces

et al. 2016

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“…To verify the possible role of the TICT state of C1 in the observed breaks in AOT/water RMs, we extended our experiments to another coumarin dye, namely, C343, which is a wellstudied probe for RMs [16,17,[19][20][21]54] and does not form a TICT state owing to cyclization of its 7-amino group. [49] Moreover, because of its more polar nature (due to the presence of a COOH group), C343 will preferentially reside in the interfacial head-group region if not in the water pools of RMs, which would simplify the observed changes with w 0 .…”

Section: Coumarin 1 In Nonaqueous Rmsmentioning

confidence: 98%

“…[17,23,24,54] The two rotational relaxation times estimated for the present systems at different w 0 values are listed in Table S1 (Supporting Information), along with their relative contributions. The average rotational relaxation times ht r i in the present systems were also calculated by using Equation (1)…”

Section: Time-resolved Anisotropy Studiesmentioning

confidence: 99%

Influence of Confined Water on the Photophysics of Dissolved Solutes in Reverse Micelles

et al. 2009

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The photophysical parameters of two probes with largely different hydrophobic character, namely, coumarin 1 and coumarin 343, are investigated in sodium bis-(2-ethylhexyl)sulfosuccinate (AOT)/hexane/water reverse micelles at various water/AOT molar ratio w(0). Correlation of photophysical parameters such as fluorescence quantum yield, fluorescence lifetime, and emission maxima with w(0) indicate distinctly different trends below and above w(0) approximately 7 for both probes. The variation of the average rotational correlation times obtained from fluorescence anisotropy decays for both probes in reverse micelles further corroborate the above observation. Similar studies were also performed in nonaqueous reverse micelles with acetonitrile as polar solvent. Similar to aqueous reverse micelles, breaks in the photophysical parameters with increasing acetonitrile/AOT molar ratios w'(0) were also observed in these cases, although at a much lower w'(0) value of 3. The present results indicate that around w(0) approximately 7 for aqueous reverse micelles (and around w'(0) approximately 3 for nonaqueous reverse micelles) a distinct change occurs in the probe microenvironment, which is rationalized on the basis of the relative populations of interfacial and core water. We propose that until the ionic head groups and counterions are fully solvated by polar solvents, that is, up to w(0) approximately 7 (or w'(0) approximately 3), the interfacial water population dominates. Above these molar ratios coalescence of excess water molecules with each other to form truncated H-bonded water clusters leads to a sizable population of core water. This is further substantiated by changes in the IR absorption spectra for the O--D stretching mode of diluted D(2)O in reverse micelles with varying w(0). Critical comparison of the present results with relevant literature reports provide clear support for the proposals made on water structure in reverse micelles. The role of relative size of the probe and the reverse micelles for differences in polar solvent to AOT ratios (w(0)=7 and w'(0)=3) in the observed breaks in the two types of reverse micelles is also discussed.

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“…This value is on the same order of magnitude as that obtained in encapsulated water molecules for reverse micelles. 58 It is to be noted that the probe is only sparingly soluble in water and remains mainly in the DX phase in the ground state. In the excited state, however, it moves to the aqueous phase and as discussed earlier ( Figure S1, Supporting Information), the fluorescence signal is generated only by the probe molecules located either at the DX-water interface or in the aqueous phase, and thus it experiences a slightly larger microviscosity than the corresponding bulk phases.…”

mentioning

confidence: 99%

Exploration of the Dynamical Evolution and the Associated Energetics of Water Nanoclusters Formed in a Hydrophobic Solvent

et al. 2009

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Exploration of the intermolecular binding energy in nanometer-sized small water clusters in hydrophobic solvents and its evolution with the increase in the cluster size until bulk-type geometry is reached constitute a fascinating area of research in contemporary chemical/biological physics. In this contribution we have used femtosecond/picosecond-resolved solvation dynamics and fluorescence anisotropy techniques to explore the dynamical evolution of water clusters in dioxane continuum as a function of water concentration. We have also used temperature dependent picosecond-resolved solvation dynamics in order to explore the magnitude of the intermolecular bonding energy in the water clusters in bulk dioxane.

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Cosurfactant Impact on Probe Molecule in Reverse Micelles

Cited by 48 publications

References 62 publications

Differences in Interactions of Benzoic Acid and Benzoate with Interfaces

Differences in Interactions of Benzoic Acid and Benzoate with Interfaces

Influence of Confined Water on the Photophysics of Dissolved Solutes in Reverse Micelles

Exploration of the Dynamical Evolution and the Associated Energetics of Water Nanoclusters Formed in a Hydrophobic Solvent

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