Nile red dye in aqueous surfactant and micellar solution.

The solubilization behavior of nile red dye in aqueous surfactant and micellar solutions was studied by optical spectroscopic techniques, dynamic light scattering, and atomic force microscopy. Nile red exhibits considerable absorption in the submicellar concentration region. When dispersed in aqueous surfactant and/or micellar solution, nile red molecules tend to form nonemissive dimers and/or H-type aggregates through π-π stacking interactions.

Polarization transfer solid-state NMR for studying surfactant phase behavior.

The phase behavior of amphiphiles, e.g., lipids and surfactants, at low water content is of great interest for many technical and pharmaceutical applications.

Localization of hydrophobic N-diazeniumdiolates in aqueous micellar solution.

The interaction of phenyl-substituted zwitterionic N-diazeniumdiolates PhCH(2)N[N(O)NO](-)(CH(2))(2)NH(3)(+) (1) and PhCH(2)N[N(O)NO](-)(CH(2))(2)NH(2)(+)CH(2)Ph (2) with aqueous micellar solutions of prototypal surfactants was investigated by means of UV/vis and (1)H NMR spectroscopy in order to establish the localization of hydrophobic N-diazeniumdiolates in micelles as a model for the binding of the NO donors in biological membranes. In the presence of sodium dodecyl sulfate (SDS), significant shifts of the apparent pK(a) values of 1 and 2 were observed, suggesting strong electrostatic interaction between the diazeniumdiolates and the negatively charged SDS micelles. No effect on both pK(a) and rate of NO release was found in the presence of Triton X-100.

Monitoring self-sorting by electrospray ionization mass spectrometry: formation intermediates and error-correction during the self-assembly of multiply threaded pseudorotaxanes.

Three binary pseudorotaxanes, which are based on two different secondary ammonium/crown ether binding motifs, have been studied by (1)H NMR and (1)H,(1)H EXSY NMR experiments with respect to their thermodynamic stabilities and their axle exchange kinetics. The stability ranking does not follow the order of axle exchange rates, and the thermodynamically most stable axle-wheel combinations assemble only slowly. On the basis of these binding motifs, a series of self-sorting systems have been studied ranging from simple four-component mixtures through sequence-specific pseudorotaxanes to multiply threaded complexes.

Transannular 1,5-hydride shift in 5-hydroxycyclooctanone: an experimental and theoretical investigation.

1H NMR measurements have shown that eight out of twelve methylene hydrogen atoms of 5-hydroxycyclooctanone (1HK) are exchanged for deuterium atoms under acidic and basic conditions. For the reaction in 7.9 M DCl/D2O, an activation energy Ea = 19.