Surfactant transition metal chelates

New surfactant octahedral Co(III) chelates 4-7 were prepared from sodium hexanitrocobaltate(III) and EDTA derivatives 8-11, respectively. The molecular compositions of 4-7 were established by combustion analyses and electrospray mass spectrometry, and their structures by 1H and 13C NMR, IR, and UV-vis spectroscopy. Surfactants 4-7 were characterized by measurement of their Krafft temperatures and critical aggregation concentrations in water. The Krafft temperatures of 4 and 5 are >23 °C, and the values of the former are greater than the corresponding values of the latter. The Krafft temperatures of 6 and 7 are ≤23 °C. Aggregated surfactants were characterized by 1H NMR spectroscopy in D2O, and 5a in water was studied by cryo-etch high resolution scanning electron microscopy. The NMR results suggested that 4-7 form small aggregates such as micelles or small vesicles, and 5a displayed characteristic segregation patterns in electron micrographs that are likely formed during the freezing and/or cryo-etch processes of sample preparation.