Dynamic Structure and Chirality Effects on ¹H and ¹³C NMR Chemical Shifts for Aerosol OT in Reversed Micelles Assisted by NOESY, ROESY, and ¹³CT₁ Studies

Abstract

The 13C NMR spin−lattice relaxation time (T 1) and 13C{H} NOE of the individual carbon atoms of each 2-ethylhexyl chain in an aerosol OT (AOT) molecule have been investigated in the reversed micellar state, and the segmental mobility of each 2-ethylhexyl chain has been discussed independently in connection with the chirality effect on the 13C chemical shifts. Measurements of the NOESY and ROESY spectra of an AOT molecule and cross-peak assignments have been made. In particular, for the ROESY spectrum, the cross-peaks arising from the dipole−dipole interaction have been used to discuss successfully the spatial proximity of the two 2-ethylhexyl chains. It has also been found that the carbon atom having the larger 1/ values provides larger secondary splitting of the 13C chemical shift. Furthermore, the dipole−dipole interaction between the H3 or H3‘ protons and other specific protons has been found to be strongly dependent on the diastereoisomers. Selective NOE measurements were also made, and the proximity of intermolecular or intramolecular two 2−ethylhexyl chains has been discussed.

Aggregate Structures of Asymmetric Di-Alkyl Phosphate Anions and the Role of Conformations about the Polar Region: SANS, Cryo-TEM, Raman Scattering, 13C NMR, and Selective NOE Studies

“…33b The intensities of the 1,1′-and 2,2′-CH 2 signals decreased under low-power decoupling of the short chain CH 3 protons (4′ for BDoP and 6′ for HDoP), indicating the presence of NOE. 20,37 The NOE value observed in the 1,1′-or 2,2′-CH 2 signals of each sample relative to that observed in the same signals of the lowest concentration sample (relative NOE value) was calculated for BDoP and HDoP. Figure 9 shows the concentration-dependence of the relative NOE value for the HDoP samples (using the lowest concentration: 0.017 mol/L) as a representative.…”

Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy

“…NMR shows restricted segmental mobility in the AOT, 35 and it is plausible that a small molecule could be trapped or bound to the AOT layer. Similarly the muoniated radical could preferentially reside at the interface between the surfactant and bulk solvents, for example through hydrogen bonding at the water/headgroup interface.…”

Complex, Dynamic Behavior of Extremely Asymmetric Di-n-Alkylphosphate-Anion Aggregates, the Long-Chain Effect and the Role of a Limiting Size: Cryo-TEM, SANS, and X-Ray Diffraction Studies

“…The very slow surface-tension equilibration in the SDHpS aqueous solution and the spontaneous droplet-lamellar transition in the SDOleS–decane–water system may be ascribed to the molecular-skeleton characteristic of these surfactants as the common structural unit of the asymmetric succinate-skeleton (O 3 S-CH­(CH 2 -COO-R 1 )-COO-R 1 , R 1 : n -alkyl group), possibly leading to the difference in the aggregation behavior between freshly prepared and aged interfaces. The effect of the spontaneous curvature of the oil–water interface − formed by the succinate-surfactant systems may play an important role.…”

“…18 The time-dependent SAXS profiles provided evidence that the droplet-lamellar transition occurs spontaneously, but very slowly at 298 K, and depends on the quantity of water solubilized into the microemulsion. The dynamic models of AOT-reversed micelles 19 and the crystal structures of the AOT-homologues 9 were used successfully to explain the aggregation behavior.…”