Surfactant Self-assembly in the Gas Phase:  Bis(2-ethylhexyl)sulfosuccinate-Alkaline Metal Ion Aggregates

Giorgi, Gianluca; Ceraulo̊, Leopoldo; Liveri, Vincenzo Turco

doi:10.1021/jp0773785

Cited by 24 publications

(58 citation statements)

References 22 publications

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“…In contrast with enormous work devoted to NaAOT aggregates in solution, only a handful of investigations have been reported concerning NaAOT aggregates as charged species in the gas phase [8][9][10][11][12][13][14][15][16], including electrospray ionization (ESI) and matrix-assisted laser desorption/ionization mass spectra [10,14], time-offlight secondary ion mass spectra [16] and infrared multiple photon dissociation spectra [13] of singly and doubly positively charged NaAOT aggregates. These measurements revealed reverse micelle-like structures for these aggregates.…”

mentioning

confidence: 99%

Mass Spectrometry Study of Multiply Negatively Charged, Gas-Phase NaAOT Micelles: How Does Charge State Affect Micellar Structure and Encapsulation?

Fang

Liu

2012

J. Am. Soc. Mass Spectrom.

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Abstract. We report the formation and characterization of multiply negatively charged sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) aggregates in the gas phase, by electrospray ionization of methanol/water solution of NaAOT followed by detection using a guided-ion-beam tandem mass spectrometer. Singly and doubly charged aggregates dominate the mass spectra with the compositions of [Na n-z AOT n ] z-(n01-18 and z01-2). Solvation by water was detected only for small aggregates [Na n-1 AOT n H 2 O] -of n03-9. Incorporation of glycine and tryptophan into [Na n-z AOT n ] z-aggregates was achieved, aimed at identifying effects of guest molecule hydrophobicity on micellar solubilization. Only one glycine molecule could be incorporated into each [Na n-z AOT n ] z-of n≥7, and at most two glycine molecules could be hosted in that of n≥13. In contrast to glycine, up to four tryptophan molecules could be accommodated within single aggregates of n≥6. However, deprotonation of tryptophan significantly decrease its affinity towards aggregates. Collision-induced dissociation (CID) was carried out for mass-selected aggregate ions, including measurements of product ion mass spectra for both empty and amino acid-containing aggregates. CID results provide a probe for aggregate structures, surfactant-solute interactions, and incorporation sites of amino acids. The present data was compared with mass spectrometry results of positively charged [Na n+z AOT n ] z+ aggregates. Contrary to their positive analogues, which form reverse micelles, negatively charged aggregates may adopt a direct micelle-like structure with AOT polar heads exposed and amino acids being adsorbed near the micellar outer surface.

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confidence: 99%

Mass Spectrometry Study of Multiply Negatively Charged, Gas-Phase NaAOT Micelles: How Does Charge State Affect Micellar Structure and Encapsulation?

Fang

Liu

2012

J. Am. Soc. Mass Spectrom.

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“…Positively and negatively charged aggregates containing alkaline metal ions have been previously described by us . In the case of positively charged AOT‐alkaline metal ion aggregates, trimeric species [AOT 3 M 4 ] + show an extra stability with respect to the other aggregates . Tandem and energy resolved mass spectrometry have shown that positively charged AOT‐alkaline metal ion aggregates mainly decompose by the loss of neutral surfactant molecules .…”

Section: Introductionmentioning

confidence: 79%

“…Gas‐phase AOTNa self‐assembling and its ability to incorporate ionic species in its aggregates have been studied by electrospray (ESI), matrix assisted laser desorption ionizations and energy‐resolved mass spectrometry . Positively and negatively charged aggregates containing alkaline metal ions have been previously described by us . In the case of positively charged AOT‐alkaline metal ion aggregates, trimeric species [AOT 3 M 4 ] + show an extra stability with respect to the other aggregates .…”

Section: Introductionmentioning

confidence: 99%

“…In the case of positively charged AOT‐alkaline metal ion aggregates, trimeric species [AOT 3 M 4 ] + show an extra stability with respect to the other aggregates . Tandem and energy resolved mass spectrometry have shown that positively charged AOT‐alkaline metal ion aggregates mainly decompose by the loss of neutral surfactant molecules . Multiply charged gas‐phase AOTNa reverse micelles and the encapsulation of glycine inside them have been recently described .…”

Section: Introductionmentioning

confidence: 99%

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Gas phase charged aggregates of bis(2-ethylhexyl)sulfosuccinate (AOT) and divalent metal ions: first evidence of AOT solvated aggregates

et al. 2011

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Assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ions have been investigated in the gas phase by electrospray ionization mass spectrometry. A variety of positively charged monometallated and mixed metal aggregates are formed. Interestingly, several ions contain solvent (MeOH, H(2)O) molecules and constitute the most abundant AOT cationic aggregates not containing sodium. These species are the first example of solvated AOT-metal ion aggregates in the gas phase. By increasing the surfactant aggregation number, the abundance of solvated species becomes lower than that of unsolvated ones. Decompositions of ionic species have been studied by tandem mass spectrometry, and their stability has been determined through energy resolved mass spectrometry. In contrast with positively charged AOT-alkaline metal ion aggregates, whose decompositions are dominated by the loss of individual surfactant molecules, AOTNa-divalent ion aggregates mainly dissociate through the cleavage of the AOT H(2)C-O bond followed by further intramolecular fragmentations. This finding, that is consistent with an enhanced chelation of divalent ions with AOT(-) head groups, has been taken as an indication that such aggregates are characterized by a reverse micelle-like organization with a ionic core formed by the metal cations interacting with the negatively charged surfactant polar heads, whereas the surfactant alkyl chains point outside.

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“…Among them, self-assembly of polymers has been demonstrated as a powerful method to generate well-ordered structures of the metal particles with uniform nano-size [20][21][22][23] . The core-shell architecture of the micelles would protect the metal nanoparticles from aggregation and makes them distribute uniformly in the solution [24] .…”

Section: Introductionmentioning

confidence: 99%

Gold-loaded polymeric micelles with temperature-modulated catalytic activity

Shi

et al. 2015

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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Four-armed amphiphilic block copolymers, polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) 4 , were synthesized by atom transfer radical polymerization (ATRP). (PS-b-PNIPAM) 4 self-assembled into micelles with PS block as core and thermoresponsive PNIPAM block as corona. The gold nanoparticles (Au NPs) with average diameter about 5.8 nm were immobilized on the surfaces of the micelles by the reduction of the corresponding ions. The micelle-supported gold nanoparticles (Au-micelles) were applied to catalyze the reduction of p-nitrophenol. Moreover, the activity of the Au-micelle catalyst could be modulated by the temperature and the Au-micelles could be easily recovered by changing the temperature and recycled four times with high catalytic activity.

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Surfactant Self-assembly in the Gas Phase: Bis(2-ethylhexyl)sulfosuccinate-Alkaline Metal Ion Aggregates

Cited by 24 publications

References 22 publications

Mass Spectrometry Study of Multiply Negatively Charged, Gas-Phase NaAOT Micelles: How Does Charge State Affect Micellar Structure and Encapsulation?

Mass Spectrometry Study of Multiply Negatively Charged, Gas-Phase NaAOT Micelles: How Does Charge State Affect Micellar Structure and Encapsulation?

Gas phase charged aggregates of bis(2-ethylhexyl)sulfosuccinate (AOT) and divalent metal ions: first evidence of AOT solvated aggregates

Gold-loaded polymeric micelles with temperature-modulated catalytic activity

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