Aggregation, adsorption, counterion binding, thermal and scattering behavior of metallosurfactant cis-[Co(en)2(C12H25NH2)Cl](NO3)2

Abstract Amphiphilic metal complexes, better known as metallosurfactants, are the emerging class of materials with a range of properties inherent to both metal complexes and surfactants. Studying the fundamental aspects of the adsorption and aggregation of these novel surfactants is necessary by looking at their potential applications. cis -Chlorobis(ethylenediamine)dodecylaminecobalt(III) nitrate (CDCN) was synthesized and its critical micelle concentration (cmc) values were determined in aqueous medium as a function of sodium nitrate concentration by using surface tension, conductivity and spectrophotometric methods. The cmc of CDCN is equal to 1.4 mmol kg −1 and compared to conventional ionic surfactants with same hydrocarbon chain length, CDCN has properties of a better surfactant. The counterion binding constant of CDCN is found to be nearly 0.8. Dynamic light scattering and small angle neutron scattering data showed that the size of the metallomicelle is strongly dependent on the added salt concentration, but not above 0.04 mol kg −1 NaNO 3 . The aggregates of CDCN have large size and from SANS data analysis they appear to exist as micellar clusters. The surface excess and area per molecule of CDCN at the cmc are equal to 2.59 × 10 −6  mol m −2 and 0.64 nm 2 , respectively.