Electrochemical and adsorption properties of PAMAM dendrimers surface-functionalized with polypyridyl cobalt complexes

Polyamidoamine dendrimers (generations 1 and 3) surface-modified with terpy ridyl cobalt complexes have been prepared and characterized by electrochemi cal and EQCM (electrochemical quartz crystal microbalance) techniques. EQCM studies of the dendrimer complexes show that they deposit onto a Pt electr ode following the Co(II/I) reduction process and that the resulting films p revent further deposition upon successive potential scanning. The effects, of electron self-exchange were observed for Co(I/II) redox processes for ad sorbed layers of the dendrimers. Further, the thermodynamics and kinetics o f adsorption of the dendrimers have been studied using electrochemical meth ods. These metallodendrimers adsorb(up to a monolayer equivalent) onto Pt e lectrodes at -0.20 V vs AE/AgCl, where the Co sites have +2 charges, and th e adsorption thermodynamics is well characterized by the Langmuir adsorptio n isotherm. The kinetics of adsorption is activation-controlled and the rat e constant is larger for the higher generation (i.e.. generation 3) metallo dendrimer.