Water Pool pH of AOT-Based W/O Microemulsions at Various Water Contents Estimated by Absorbance Ratio of Pyranine

Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design

“…As the accuracy of the classical definition of pH based on proton activity is at the very least uncertain in RM, researchers have reoriented toward concepts such as "acidity" and "basicity", which are considered to be more adequate in such systems. These concepts are associated with indirect measurements based on acidity scales using a molecular probe in a pH-sensitive reaction, and they are generally evaluated through a spectroscopic method [95], i.e., either ultraviolet/visible light (UV/Vis) absorption based on the shifts of spectral peaks or (steady-state and time-resolved) fluorescence techniques using a pH-sensitive excitation spectrum [89]. In the latter case, probe molecules presenting excited-state proton transfer may reside in different regions of the water pool [91], e.g., 2-naphthol-6,8disulfonate sodium salt located in free water [96] or 7-azaindole mostly present in the interfacial zone of AOT RMs [97], and their fluorescence responses suggest/confirm the heterogeneity of the water structure in RMs.…”

The hydrolysis of phenyl trifluoroacetate in AOT/n-heptane RMs as a sensor of the encapsulated water structure

“…1). [13][14][15][16][17][18] A unique microenvironment for carrying out a variety of chemical and biochemical reactions is found in the polar cores of RMs which have also been used as model systems for studying various reactions in connement. 11,[19][20][21] Despite their simplicity, they provide an excellent method to study fundamental effects of connement.…”

“…11,[19][20][21] Despite their simplicity, they provide an excellent method to study fundamental effects of connement. Moreover, the unique AOT interfacial properties, such as the "pH", 14,15,18 the ionic strength, 9,10,15 micropolarity 10 among others make the interfacial water molecules very interesting to be studied as reactant. The extensive use of RMs as nanoreactors for aqueous phase reactions requires precise knowledge of the states of the enclosed water.…”

Versatility of Reverse Micelles: From Biomimetic Model to Nano(Bio)Sensors Design

“…As the accuracy of the classical definition of pH based on proton activity is obvious at least uncertain in RM, the researchers have reoriented towards concepts like "acidity" and "basicity" which are considered to be more adequate in such systems. These concepts are associated with indirect measurements based on acidity scales of a molecular probe in a pH-sensitive reaction and generally performed through a spectroscopic method [85], either a UV-Vis absorption based on shifts of spectral peaks or (steady-state and time resolved) fluorescence techniques using a pHsensitive excitation spectrum [79]. In the latter case, probe molecules presenting excited state proton transfer may be resided in different regions of water-pool [86], e.g., 2-naphthol-6,8-disulfonate sodium salt located in the free water [87] or 7-azaindole mostly present in the interfacial zone of AOT-RMs [88], and their fluorescence responses suggest/confirm the heterogeneity of water structure in RMs.…”