Cyclic siloxanes and silsesquioxanes as cores and frameworks for the construction of ferrocenyl dendrimers and polymers

Abstract

Starting from 1,3,5,7-tetramethylcyclotetrasiloxane as core, novel ferrocenyl silicon-containing dendrimers have been constructed up to the third generation, which contains 16 peripheral ferrocene moieties. As precursors of these ferrocenyl dendritic molecules, Si[bond]Cl- and Si[bond]allyl-terminated cyclotetrasiloxane-based dendrimers were also built step by step, by the repetition of hydrosilylation and alkenylation reactions as growing steps. The dendritic structures have been confirmed by 1 H, 13 C and 29 Si NMR, infrared spectroscopy, elemental analysis, mass spectrometry and vapor-pressure osmometry. Solution electrochemical studies showed that all the ferrocenyl redox centers attached to the dendritic surface behave as independent, electronically isolated units, so that the dendrimers exchange all the electrons simultaneously at the same potential. We also describe the application of the first redox-active ferrocenyl polymer containing an octakis(dimethylsiloxy)octasilsesquioxane framework, as a mediator in the electrocatalytic oxidation of ascorbic acid. Copyright © 1999 John Wiley & Sons, Ltd.