Comparison Between Aqueous and Nonaqueous AOT-Heptane Reverse Micelles Using Acridine Orange as Molecular Probe

Falcone, R. Darío; Correa, N. Mariano; Biasutti, M. Alicia; Silber, Juana J.

doi:10.3390/50300553

Cited by 6 publications

(6 citation statements)

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“…Despite the importance that they can have in the use of these systems as microreactors for reactions taking place with reagents that may react with water [17], there exist few reported studies related with the partitioning of solutes in nonaqueous reverse micellar solution [16,17,[21][22][23].…”

Section: Introductionmentioning

confidence: 97%

The use of acridine orange base (AOB) as molecular probe to characterize nonaqueous AOT reverse micelles

Falcone

Correa

Biasutti

et al. 2006

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 97%

The use of acridine orange base (AOB) as molecular probe to characterize nonaqueous AOT reverse micelles

Falcone

Correa

Biasutti

et al. 2006

Journal of Colloid and Interface Science

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“…Both types of aggregates can coexist in a solution [12] providing the opportunity to explore the entropy/enthalpy balance in depth [13]. The type of aggregation can be critically important for the efficiency of a given organic dye as a fluorescence sensor [14,15,16,17]. The position of the fluorescence maximum changes characteristically upon aggregation [18].…”

Section: Introductionmentioning

confidence: 99%

The Partner Does Matter: The Structure of Heteroaggregates of Acridine Orange in Water

Shenderovich

2019

Molecules

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Self-assembly of organic molecules in aqueous solutions is governed by a delicate entropy/enthalpy balance. Even small changes in their intermolecular interactions can cause critical changes in the structure of the aggregates and their spectral properties. The experimental results reported here demonstrate that protonated cations of acridine orange, acridine, and acridin-9-amine form stable J-heteroaggregates when in water. The structures of these aggregates are justified by the homonuclear 1H cross-relaxation nuclear magnetic resonance (NMR). The absorption and fluorescence of these aggregates deviate characteristically from the known H-homoaggregates of the protonated cations of acridine orange. The latter makes acridine orange a handy optical sensor for soft matter studies.

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“…In this sense, some preliminary results were previously reported. 22 In addition, the fluorescence lifetimes of all the species detected in the micellar systems studied have been characterized. The comparison of the decays under different conditions gives information on the location sites of the probes as well as the effect of the polarity and water structure at the micelle domain.…”

Section: Introductionmentioning

confidence: 99%

Acid−Base and Aggregation Processes of Acridine Orange Base in n-Heptane/AOT/Water Reverse Micelles

et al. 2002

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The properties of the base acridine orange (AOB) in n-heptane/AOT/water reverse micelles were investigated by using absorption, fluorescence, and single photon counting techniques. For comparison, studies in homogeneous media (water and n-heptane) were also performed. The absorption spectra of AOB in water at pH < 10 in the range of [AOB] ) 10 -6 -10 -4 M show two bands at 467 and 492 nm which were attributed to the dimer ((AOBH)2 2+ ) and monomer (AOBH + ) species, respectively. At pH > 10 in the same [AOB] range, only the basic form, AOB, was detected with a band in the visible at λmax ) 435 nm, which obeys Lambert-Beer's law. This species was also the only one detected in n-heptane at 417 nm. These results show that only the protonated base dimerizes as confirmed by fluorescence techniques. The absorption spectra of AOB in the micellar media at various W0 (W0 ) [H2O]/[AOT]) and pH ) 4, working above the operational critical micellar concentration and below [AOT] ) 3 × 10 -3 M, show the disappearance of the band originally present in n-heptane and the appearance of the bands attributable to the protonated base mostly as the dimer, (AOBH)2 2+ . Above this concentration, the absorption band corresponding to AOBH + is the predominant one. There are two isosbestic points, at 426 and 475 nm. Three processes can account for the behavior of AOB in the reverse micelles: (1) distribution of the dye between the organic phase and the micellar interface followed by AOB protonation to give AOBH + , (2) dimerization of AOBH + at the interface at low [AOT], and (3) the conversion of (AOBH)2 2+ to AOBH + by the micelle at [AOT] > 3 × 10 -3 M. The spectral changes allow us to estimate the equilibrium constants for the processes at different W0; the dimerization process is favorable at low water content. The fluorescence spectra of these species show at 650 nm the band for (AOBH)2 2+ and at 550 nm the one for AOBH + . By varying the experimental conditions, the fluorescence decay times for AOB (in n-heptane and water) as well as for AOBH + and (AOBH)2 2+ in water and in AOT reverse micelles were determined. The results were used to explain the micellar influence on AOB's protonation and aggregation processes. The fluorescence decay times at low W0 are higher than that obtained in bulk water. On increasing W0, the fluorescence decay times tend to the value obtained in water at the same pH.

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Comparison Between Aqueous and Nonaqueous AOT-Heptane Reverse Micelles Using Acridine Orange as Molecular Probe

Cited by 6 publications

References 5 publications

The use of acridine orange base (AOB) as molecular probe to characterize nonaqueous AOT reverse micelles

The use of acridine orange base (AOB) as molecular probe to characterize nonaqueous AOT reverse micelles

The Partner Does Matter: The Structure of Heteroaggregates of Acridine Orange in Water

Acid−Base and Aggregation Processes of Acridine Orange Base in n-Heptane/AOT/Water Reverse Micelles

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