Preparation of multilayered nanocomposites of polyoxometalates and poly(amidoamine) dendrimers

A layer-by-layer (LBL) deposition technique based on electrostatic attraction of oppositely charged species was used to fabricate multilayer films consisting of polyoxometalates (POMs) (Keggin-structure PMo12O403- or Dawson-structure P2W18O626-) and a generation-4 poly(amidoamine) dendrimer (G4-PAMAM) on quartz treated with poly(diallyldimethylammonium chloride) and gold treated with (aminothiophenol (4-ATP). Both of the UV-visible spectrophotometry and cyclic voltammetry proved a successful formation of uniform and well-defined self-assemblies with multilayered supramolecular structure. With PM0(12)O(40)(3-) each layer contained 4.6 x 10(-11) mol cm(-2). Direct attachment of PMo12O403- yielded a surface excess of 3.6 x 10(-11) mol cm(-1) in that monolayer. The comparison suggested an expansion of the effective surface area by the multicharged macromolecule, G4-PAMAM. The multilayer films mediated the reduction of iodate and of nitrite. (C) 2001 Elsevier Science B.V. All rights reserved.