Thermal, aggregation, counterion binding, light scattering, and adsorption behavior of cis-chlorobis(ethylenediamine)dodecylaminecobalt(III) perchlorate metallosurfactant in aqueous sodium perchlorate medium

Abstract

Studying the fundamental aspects of aggregation and adsorption of metallosurfactants is necessary by looking at the potential applications of these novel surfactants. cis-Chlorobis(ethylenediamine)dodecylaminecobalt(III) perchlorate (CDCP) metallosurfactant was synthesized and its thermal gravimetric analysis showed that it is stable up to 217 °C. Critical micelle concentration (cmc) of CDCP in aqueous sodium perchlorate medium was determined by using surface tension, conductivity, and spectrophotometric methods. It is shown that the cmcs of metallosurfactants do not follow the trend according to the positions of the counterions in the Hofmeister series, which is contrary to the trend observed in the case of conventional ionic surfactants. The counterion binding constant of CDCP is equal to 0.81. The variation of surface excess of CDCP with sodium perchlorate concentration exhibits a minimum. Dynamic light scattering measurements showed the presence of large size aggregates of CDCP in solution, and these aggregates grow further as the counterion concentration increased.