The flexibility of periphery enhances the electrochemical reversibility of ferrocenyl-terminated polyphenylene dendrimers

Abstract

Four dendrimers of the first and second generations containing rigid polyphenylene interior and flexible ferrocenyl-terminated alkyl arms (CH2)m(C5H4)Fe(C5H5) (m = 6, 11) were synthesized by combining two types of “click” reactions: Diels-Alder and copper-catalyzed azide-alkyne cycloaddition reactions. The resulting compounds were characterized by NMR spectroscopy, gel permeation chromatography, and cyclic voltammetry (CV). CVs of the dendrimers show a single chemically reversible wave. In contrast to wholly aromatic redox-active dendrimers, a combination of rigid polyphenylene interior with flexible alkylferrocenyl periphery provides an electrochemically reversible redox process. The dendrimers exhibit strong adsorption onto the Pt electrode upon oxidation, thus providing fabrication of stable modified electrodes coated with a second-generation dendrimer.