Synthesis, characterisation, electronic spectra and electrochemical investigation of ferrocenyl-terminated dendrimers

Two new dodecaferrocenyl dendrimers have been prepared using a sixfold Sonogashira coupling reaction and sixfold Huisgen cycloaddition, respectively. In addition, a dendron containing four ferrocenyl groups has been synthesised by conventional synthetic methods. Electrochemical studies have shown that all the ferrocene units are electrochemically equivalent. Moreover, when treated with acid these compounds form multicharged methylium near-infrared-absorbing dendritic dyes with a high extinction coefficient.