NMR-Studies of the Solubilisation of Aromatic Compounds in Cetyltrimethylammonium Bromide Solution. II.

Eriksson, Jan Christer; Gillberg, Gunilla; Røst, Erling; Vestersjø, Egil; Stokke, O.; Bunnenberg, E.; Djerassi, Carl; Records, Ruth

doi:10.3891/acta.chem.scand.20-2019

Cited by 302 publications

(151 citation statements)

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“…We based our choice of this molecule on the NMR data of Eriksson and Gillberg. 18 Chemical shift measurements of CTAB protons show a large shift of N-CH and R-CH protons upon addition of even small amounts of DMA. Such a shift is consistent with localization of an aromatic ring near these protons.…”

Section: Experimental Systemmentioning

confidence: 99%

“…This is interpreted as due to penetration of DMA into the micelle occurring at very high DMA concentrations after saturation of the surface region. 18 To further confirm the localization of the DMA at the hydrocarbon/aqueous interface, we have carefully studied the fluorescence spectrum of DMA in the three micelles and in a variety of solvents. The DMA fluorescence shows a pronounced red shift as the solvent becomes more polar.…”

Section: Experimental Systemmentioning

confidence: 99%

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Photoinduced Electron Transfer on the Surfaces of Micelles

1997

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Photoinduced electron transfer between N,N-dimethylaniline (DMA) and octadecylrhodamine B (ODRB) is studied on the surfaces of three alkyltrimethylammonium bromide micelles: dodecyl-(DTAB), tetradecyl-(TTAB), and hexadecyltrimethylammonium bromide (CTAB). The DMA and ODRB molecules are localized at the micelle surface. Time-resolved fluorescence and fluorescence yield data are presented and analyzed with the theoretical methods of ref 1. Lateral diffusion of the molecules over the micelle surfaces is included. Although the three micelles are structurally similar, pronounced differences in the electron-transfer kinetics are observed, with the overall amount of electron transfer increasing with alkyl chain length for the same DMA surface packing fraction. This result is attributed to differences in the solvent reorganization energy, possibly due to varying extents of water penetration into the headgroup regions of the three micelles. As the surfactant chain length increases, the solvent reorganization energy is reduced, resulting in faster electron transfer.

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Section: Experimental Systemmentioning

confidence: 99%

Section: Experimental Systemmentioning

confidence: 99%

Photoinduced Electron Transfer on the Surfaces of Micelles

1997

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“…NMR experiments show that the DMA molecules are located in the headgroup region of the micelles (ref 1 includes a detailed verification of this point). 18,61 R is the distance from the center of the micelle to the center of the donor/acceptor molecule. R, given in Table 1, is calculated for each micelle using the Tanford equation, R ) 1.5 Å + 1.265 Å‚T, where T is the number of carbons in the hydrocarbon tail.…”

Section: Experimental Systemsmentioning

confidence: 99%

“…Micelles have been studied by techniques such as NMR, 18,19 X-ray scattering, 20,21 neutron scattering, 22 light scattering, 23,24 cryo-transmission electron microscopy (TEM), 25,26 molecular dynamics simulations, 27,28 and Monte Carlo simulations. 29 In addition to their important biological and industrial applications, micelles have long been of interest to the electron-transfer community.…”

Section: Introductionmentioning

confidence: 99%

Solvent Reorganization Energy and Free Energy Change for Donor/Acceptor Electron Transfer at Micelle Surfaces: Theory and Experiment

et al. 1998

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Theories are presented for calculating the solvent reorganization energy and the free energy change which occur in photoinduced donor/acceptor electron transfer at the surface of micelles. The theories are based on the Marcus theory for spherical reactants in a dielectric continuum. The micelle is modeled with regions of differing dielectric properties, representing the micelle core, the headgroup region, and the surrounding water. The free energy change accompanying electron transfer can be calculated from redox measurements made in bulk liquids. The theories are applied to previously published photoinduced intermolecular electron-transfer data between octadecylrhodamine B (ODRB) and N,N-dimethylaniline (DMA) molecules.1 The ODRB and DMA molecules are located in the surface region of three different types of surfactant micelles: dodecyl-, tetradecyl-, and cetyl-trimethylammonium bromide (DTAB, TTAB, and CTAB, respectively). The data show an increased rate of electron transfer with increasing micelle radius. Application of the new theory to the electron-transfer data along with information provided by neutron scattering experiments show that the headgroup regions of the three micelles have different dielectric constants because water penetration into the headgroup regions decreases as the surfactant length increases.

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“…One of the most widely used methods for determining the location of aromatic hydrocarbons solubilized in micelles is to monitor the ring current shifts on the IH resonances of the surfactant alkyl chain (23)(24)(25)(26)(27). It is assumed that the observation of an aromatic ring current shift on a surfactant segment is evidence that on average the aromatic solubilizate is located in the vicinity of the surfactant segment.…”

Section: Introductionmentioning

confidence: 99%

NMR studies of hydrocarbons solubilized in aqueous micellar solutions

Wasylishen¹,

Kwak²,

Gao³

et al. 1991

Can. J. Chem.

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. 69, 822 (1991).Information concerning the solubilization of hydrocarbons in ionic surfactant micelles was obtained from 'H NMR relaxation, 'H NMR chemical shifts, and 'H NMR paramagnetic relaxation measurements. The rotational motion of deuterated hydrocarbons, which is related to the micellar microviscosity at the location of the hydrocarbons, was probed by ' H NMR relaxation. The relaxation data are interpreted using both the two-step and the single-step models, and the results are discussed in terms of the micellar microviscosity and the location of the hydrocarbons in micelles. The location of the hydrocarbons in micelles was further investigated by determining the aromatic ring current-induced 'H chemical shifts along the surfactant alkyl chain and by comparing the 'H spin-lattice relaxation enhancement of the hydrocarbons and the surfactant alkyl chain, induced by ~n ' ' on the micellar surface. The hydrocarbons used include benzene, naphthalene, acenaphthalene, triphenylene, cyclohexane, cyclododecane, and tert-butylcyclohexane and the surfactants studied are hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromide; hexadecyl-, tetradccyl-, and dodecylpyridinium halide; and sodium dodecyl sulfate. The results indicate that the micellar microviscosity at the location of saturated hydrocarbons is approximately 5 cP for both the cationic and anionic micelles, whereas the micellar microviscosity at the location of unsaturated hydrocarbons is much higher. The unsaturated hydrocarbons are found to reside primarily near the surfactant headgroup in the cationic micelles, but are distributed evenly throughout the anionic SDS micelles. The saturated hydrocarbons appear to be located in the interior of the micelles. 822 (1991). Utilisant la relaxation RMN du 'H, les dCplacements chimiques en RMN du 'H et des mesurcs de relaxation paramagnktique en RMN du 'H, on a obtenu de I'information concernant la solubilisation d'hydrocarbures dans des micelles d'agents de surfaceioniques. Pour Ctudier le mouvement de rotation des hydrocarbures deutCrCs qui est reliC la microviscositC micellaire au point de location des hydrocarbures, on a fait appel h la relaxation en RMN du 'H. On a interprCte les donnCes de relaxation utilisant les modkles en une ainsi qu'en deux Ctapes et on discute des rCsultats en fonction de la microviscositC micellaire et de la position des hydrocarbures dans les micelles. On a rCalisC une Ctude plus approfondie de I'influence de la position des hydrocarbures dans les micelles en determinant les dCplacements chimiques induits par le courant du noyau aromatique le long de la chaine alkyle de I'agent de surface et en comparant les augmentations des relaxations spin-reseau du 'H des hydrocarbures et de la chaine alkyle de I'agent de surface qui sont induites par du ~n ' .~ sur la surface micellairc. Les hydrocarbures utilisks sont le benzene, le naphtalkne, I'acCnaphtalkne, le triphknylkne, le cyclohexane, le cyclododCcane et le terl-butylcyclohexane alors que les agents de surface ttudiCs sont les ...

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NMR-Studies of the Solubilisation of Aromatic Compounds in Cetyltrimethylammonium Bromide Solution. II.

Cited by 302 publications

References 0 publications

Photoinduced Electron Transfer on the Surfaces of Micelles

Photoinduced Electron Transfer on the Surfaces of Micelles

Solvent Reorganization Energy and Free Energy Change for Donor/Acceptor Electron Transfer at Micelle Surfaces: Theory and Experiment

NMR studies of hydrocarbons solubilized in aqueous micellar solutions

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