Convergent synthesis of ferrocene dendrimers: The use of multitopic dendrons with disrupted conjugation

Dendrimers that are peripheraly functionalized with electrochemically active groups can be potentially used as multielectron redox catalysts, electron reservoirs, electrode modifiers, ion sensors, and mimics of biological redox processes.(1) in view of this, syntheses of peripherally functionalized redox-active dendrimers have been the focus of many recent studies.(2) Since ferrocenes show stable redox properties and are easy to functionalize,(3) ferrocene dendrimers are a widely studied class of redox-active dendrimers.(4) Until now, most of these ferrocene dendrimers have been prepared via the divergent approach where multiple ferrocene residues were coupled to the surface of a preformed dendrimer in the ultimate synthetic step. Such a strategy often leads to constitutional defects due to incomplete couplings, especially at higher generations. This, in turn, can severely affect the overall electrochemical properties of the dendrimers. To circumvent this, convergent syntheses(5) of ferrocene dendrimers, albeit a few, have recently appeared in the literature,(6) which prompted us to disclose here our own results.