Electrochemically active dendrimers for the manufacture of multilayer films: Electrochemical deposition or polymerization process by end-capped triarylamine or carbazole dendrimer

Abstract

Two different end-capped triarylamine and carbazole dendrimers of the types Gn-2n+1NPB and Gn-2n+1CBP (n ) 1, 2, 3, 4) were prepared by divergent synthesis by reacting diethenyl propagating carbosilane dendrimers with suitable functional groups, such as naphthylphenylaminophenyl (NPB) and carbazolylphenyl (CBP) units. The electrochemical studies of these two series showed that the electrochemical properties of each dendrimer in both solution and on the immobilized electrode were dependent on the generation of dendrites and type of periphery group. Gn-2n+1NPB dendrimers (n ) 3, 4) underwent oxidative precipitation on the electrode surface without a proceeding electrochemical reaction only to form highly charged ammonium cations, whereas the Gn-2n+1CBP dendrimers produced cross-linked polymers via an oxidative polymerization process. The ammonium cationic species of the G3-16NPB dendron was confirmed on the basis of the characteristic 1s peak of the F atom in X-ray photoelectron spectroscopy (XPS). Overall, the electrochemically activated G3-16NPB dendron transforms to a highly charged species with peripheral NR3 +BF4 - units to undergo an electrodeposition (ED) process. As a result, the NPB and CBP dendrimers produce dissimilar deposited films, exhibiting different surface morphology and hydrophilicity based on atomic force microscope and contact angle measurements. Using these two dissimilar electrochemical deposition processes, a new method for fabricating multilayer thin films on a conducting substrate was demonstrated successfully. © 2010 American Chemical Society.