Nanostructures in n-Octanol Equilibrated with Additives and/or Water

• DOI: 10.1021/acs.langmuir.8b00142
• Publication Date: 2018-04-24T04:07:31Z
• Authors: Gregor Cevc; Ida Berts; Stefan F. Fischer; Joachim O. Rädler; Bert Nickel
• Keywords: Octanol

Fluid fatty alcohols are believed to be nanostructured but broadly amorphous (i.e., noncrystalline) fluids and solvents, including the most popular tissue mimetic, hydrated n-octanol hydro-octanol). To check this premise, we studied dry octanol hydro-octanol as a model of relatively short fluid n-alkanols with small-angle X-ray scattering (SAXS). We also combined alkanol matching alkane octane) common anti-inflammatory pain killer (ketoprofen). This revealed that (hydro-)octanol arguably any other alcohol form mesophase. Its basic structural motif regularly packed polar nanoclusters, reflected in inner peak SAXS diffractogram n-alkanols. The nanoclusters resemble tiny, (inverse) bilayer fragments, located on thermally smeared para-crystalline lattice. Additives can change only moderately, if at all. For example, octane drug ketoprofen added enlarge little because mixture's packing frustration. associate bring more water into hydro-octanol, an additive must hence transform nanoclusters: it expands them irregularly distributed aqueous lacunae proto-microemulsion, previously unknown Guinier's signal. A "weak" weakly or nonpolar) moreover create size-limited lacunae. Coexistence well size variability latter subvert concept octanol-water partition coefficient, which relies compartment homogeneity. In turn, opens new possibilities for interfacial catalysis. Reinterpreting "octanol-water coefficient" data terms association binding constant(s) could furthermore diminish molecular lipophilicity description pave ground toward precise theoretical quantification prediction properties.