Host-guest directed assembly of gold nanoparticle arrays

The formation of a three-dimensional assembly of gold nanoparticles driven by host-guest interactions is described. Assembly is achieved via host-guest interactions between cyclodextrin-modified gold nanoparticles which associate with the adamantane unit of a redox active metal complex [Os(CAIPA)(3)](ClO(4))(2), where CAIPA is 2-(4-carboxyphenyl)imidazo[4,5-f][1,10]-phenanthroline-1-adamantylamine. The electrochemical properties of thin films formed on glassy carbon electrodes have been probed using cyclic voltammetry. In aqueous LiClO(4), the homogeneous charge transport diffusion coefficient, D(CT), is (8.4 +/- 0.4) x 10(-9) cm(2) s(-1) for both oxidation and reduction of the osmium complexes. Significantly, this charge transport rate is significantly larger than that obtained for a solid deposit of [Os(CAIPA)(3)](ClO(4))(2) alone where D(CT) is 2.3 x 10(-10) cm(2) s(-1). The higher D(CT) value observed for the nanoparticle arrays suggests that the incorporated nanoparticles facilitate electron transfer between the bound osmium centers.