Interaction of a "nido"-ruthenium terpyridylamine complex with charged elongated micellar scaffolds.

Influence on ionic surfactants by a specially designed terpyridylamine ligand and the ruthenium(II) complex formed with it has been studied in aqueous solution. The ligand coordinates to Ru(2+) into an octahedral geometry in such a way that the final form takes a "nido" or nest-like structure. The substitution on the pyridinyl moiety is kept at the ortho position to acquire the specified geometry. Similar complexes have been reported to have anti-tumor properties and thus the ruthenium complexes can effectively replace platinum complexes that serve the same purpose but with certain drawbacks. The "nido" geometry was chosen to minimize the cytotoxicity that creeps in when para substituents of the pyridinyl moiety are used. The latter variety forms a dendridic scaffold. In presence of both the ligand and the complex, ionic surfactants form elongated aggregates. The surface charge of those aggregates decides the nature of interaction of the ligand and the complex formed therefore. Interaction with anionic surfactant scaffold is found to be stronger than the cationic one.