Synthesis and characterization of an amphiphilic cobalt cage complex with aza-crown spacer

The synthesis, spectrophotometric and surfactant properties of a novel amphiphilic cobalt cage metallosurfactant with an aza-oxa crown ether spacer and dodecyl hydrocarbon tail are reported. Surface pressure isotherms with Group I and Group II metal solution subphases indicate increasing interaction of the crown moiety with Ca2+, Na+, K+, Li+/Ba2+ and Mg2+ ions in that order, with mean molecular areas of the effective head group at the surface ranging from 141 Å2 to 219 Å2. The critical micelle concentrations determined by surface tension measurements of the unmetallated ligand and the metallosurfactant are 1.98 mM and 0.66 mM respectively. Wormlike micelles and vesicles are observed with atomic force microscopy after multilayer Langmuir Blodgett film deposition on a glass substrate.

Graphical AbstractA novel cobalt cage aza-crown amphiphile is described and its mean molecular area in a compressed monolayer estimated from Langmuir isotherms. In the presence of alkali and alkali earth metals, preferential coordination to magnesium ions and large solvated ions by a crown subunit is observed at the interfacial zone.Figure optionsDownload full-size imageDownload as PowerPoint slide