Aggregation states of water in reversed AOT micelles: Raman evidence

D'Aprano, Alessandro; Lizzio, A.A.; Liveri, Vincenzo Turco; Aliotta, F.; Vasi, C.; Migliardo, P.

doi:10.1021/j100326a038

Cited by 111 publications

(76 citation statements)

References 3 publications

(2 reference statements)

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“…19 The water solubilized in AOT/H 2 O/alkane microemulsions is similar in many respects to the interfacial water present near biological membranes or at protein surfaces. 20,21 The unusual behavior of this water has been attributed to its strong interaction with the ionic head groups of the surfactant and counterions as well as to an overall disruption of the three-dimensional hydrogen-bonded network usually present in bulk water.…”

Section: -15mentioning

confidence: 99%

Spectroscopic Properties of Quercetin-3-O-rhamnoside and Quercetin-3-O-rutinoside in Aerosol-OT Reverse Micelles

Park¹,

Shin²,

Park³

et al. 2011

Bulletin of the Korean Chemical Society

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The anomalous spectroscopic properties of quercetin-3-O-rhamnoside (QCRM) and quercetin-3-O-rutinoside (QCRT) in AOT reverse micelle were studied. The excited state intramolecular proton transfer (ESIPT) occurs through the strong hydrogen bond between the -OH at position 5 and the carbonyl oxygen. Because the ESIPT can only happens in the S 1 state and the Franck-Condon factor involved in the S 2 → S 1 internal conversion is small, the S 2 → S o emission alone appears. Because the molecular planarity is improved at the interior of the micelle, the excited state intramolecular charge transfer in the S 1 state is extended, and the excited state is more tolerable for any quenching effects in the micelle. Therefore, an S 1 → S o emission was newly discovered under this micelle microenvironment. For the S 2 → S o emission, the quantum yields increase but the quantum yield of the S 1 → S o emission approximately decreases as the water concentration in the micelle increases.

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Section: -15mentioning

confidence: 99%

Spectroscopic Properties of Quercetin-3-O-rhamnoside and Quercetin-3-O-rutinoside in Aerosol-OT Reverse Micelles

Park¹,

Shin²,

Park³

et al. 2011

Bulletin of the Korean Chemical Society

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“…The different behavior between 1-alkenes and 2-alkenes can be attributed to the reaction rates of Br 2 toward the alkenes; the bromination of 2-alkenes is much faster than that of 1-alkenes because 2-alkenes have more electron-donating groups than 1-alkenes. 34 Table 1 37 assigned ''bonded'' and ''bulk'' waters. Figure 10 shows the effects of strong acids, such as HCl, HNO 3 , and HClO 4 , on the value of H 2 O in the CHCl 3 / CTAB reverse system of W ¼ 2:0 at 25 C. The sample of HNO 3 was used just after preparation because the oxidation reaction proceeded as a function of time.…”

Section: à3mentioning

confidence: 99%

Great Enhancement in the Oxidation Ability of Dilute Nitric Acid in Nanoscale Water-Droplets of Reverse Micelle Systems

Hojo¹,

Ueda²,

Daike³

et al. 2006

Bulletin of the Chemical Society of Japan

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In reverse micelle systems, a large enhancement of the oxidation ability of dilute nitric acid was discovered, and its oxidation mechanism was explored. The Br À ion in the surfactant, CTAB, was oxidized to Br 2 (or Br 3 À ) in the CHCl 3 / CTAB/H 2 O reverse micelle system with W ¼ 1:0{4:0 by diluted nitric acid (0.25-2.5 mol dm À3 in 1.0 vol % H 2 O portion) at 15-40 C where CTAB stands for cetyltrimethylammonium bromide, and the W value is the ratio of [. At higher concentrations of nitric acid and temperatures, faster reactions occurred. Otherwise, long reaction times were needed, e.g., 10 h for 1.0 mol dm À3 HNO 3 at 25 C. Light or ambient oxygen did not appear to affect the reaction. The ratio of produced Br 2 or (Br 3 À ) to the initial amount of HNO 3 indicated the following reaction scheme:The nitroyl ion (or nitronium ion), NO 2 þ , was proposed as the intermediate active species. The addition of HClO 4 as a proton source caused the complete reduction of N(V) as follows: The nitrate ion has high chemical stability, especially at low concentrations. Standard redox potentials indicate that it should serve as an excellent oxidizing agent, but in order to react with suitable reactants to form elemental nitrogen or ammonia, special conditions are required, such as the presence of catalysts and high temperature and pressure.1 Concentrated nitric acid has strong oxidation ability, although dilute nitric acid in aqueous solution at room temperature exhibits no apparent oxidation trend. Cotton and Wilkinson have described that nitric acid with a concentration of less than 2 mol dm À3 has almost no oxidation ability.2 Mixtures of concentrated nitric acid and sulfuric acid (''mixed acid'') are used for nitration of organic compounds, and the nitroyl ion (or nitronium ion) NO 2 þ is regarded as the active intermediate. 3 Raman spectra of NO 2 þ have been observed in solution 4 as well as in the solid state.5 Using 14 N NMR, Ross et al. 6 have examined the nitric acid/nitronium ion equilibrium in aqueous sulfuric acid. Dimeric nitric acid, (HNO 3 ) 2 or (DNO 3 ) 2 , was detected by FTIR in HNO 3 or DNO 3 :H 2 O:Ar matrices. 7 We have been studying the structure of water in nanoscale water-droplets of reverse micelles, stabilized by surfactants in organic solvents. 8 The size of the ''water-pool'' or ''water-droplet'' may vary from 1 to %100 8 It is well known that the properties of water localized in the interior of reverse micelles differ from those of bulk water, and the difference becomes progressively smaller as the amount of water in the micelle system increases.10

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“…20 The water solubilized in a AOT reverse micelle is similar to the interfacial water near biological membranes or at protein surfaces. 21,22 The peculiar behavior of this water has been attributed to its strong interaction with the ionic head groups of the surfactant and counter ions as well as to the overall disruption of the three-dimensional hydrogen bond network usually present in bulk water. [23][24][25][26] For this reason, the AOT micelle has been regarded to behave like a membrane mimetic system.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Properties of Quercetin in AOT Reverse Micelles

Park¹,

Im²,

Seo³

et al. 2014

Bulletin of the Korean Chemical Society

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The spectroscopic properties of quercetin (QCT) were studied in the AOT reverse micelle by fluorescence spectroscopy. Because the molecular structure of QCT is completely planar, excited state intramolecular proton transfer (ESIPT) occurs between the -OH at C(5) and carbonyl oxygen via intramolecular hydrogen bonding. This ESIPT happens at the S1 state but not at the S2 state. Because QCT is a good donor-acceptor-conjugated molecule at the excited state, this molecule can emit strong fluorescence but shows no S1 → So emission due to this ESIPT. Since the S2 → S1 internal conversion was very slow due to the small Franck-Condon factors, S2 → So fluorescence emission was observed. All of the experimental results indicated that the QCT resided at the bound water interface and that the position of solute did not change significantly in the micelle at various water concentrations.

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Aggregation states of water in reversed AOT micelles: Raman evidence

Cited by 111 publications

References 3 publications

Spectroscopic Properties of Quercetin-3-O-rhamnoside and Quercetin-3-O-rutinoside in Aerosol-OT Reverse Micelles

Spectroscopic Properties of Quercetin-3-O-rhamnoside and Quercetin-3-O-rutinoside in Aerosol-OT Reverse Micelles

Great Enhancement in the Oxidation Ability of Dilute Nitric Acid in Nanoscale Water-Droplets of Reverse Micelle Systems

Spectroscopic Properties of Quercetin in AOT Reverse Micelles

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