Synthesis, characterization and biological properties of new hybrid carbosilane–viologen–phosphorus dendrimers

Abstract

A series of hybrid carbosilane–viologen–phosphorus dendrimers was prepared, as a new example of the synthetic “onion peel” approach. This is based on a convergent strategy by combination of double alkylation of 4,4-bipyridine units with two different halogenated reagents, one of them as a carbosilane dendron, and their subsequent ligation to a hexafunctionalized phosphorus core through amine–aldehyde condensation reactions. In these systems two kinds of cationic groups were included: those located at the branches due to viologen quaternized units and those related to the ammonium groups at the surface of carbosilane wedges. This feature constitutes a novel situation to be explored in the search for new physical–chemical and biological properties, respecting traditional dendritic architectures. The biological properties of two of these hybrid molecules have been studied, focusing the investigation on their interactions with plasma proteins like human serum albumin (HSA), cytotoxicity and hemotoxicity experiments. Although the observed biological behaviors were mainly related to the presence of outer positive charges, in some cases the inner positive charges acted as fine tuning factors.