Formation, characterization, and properties of nanostructured [Ru(bpy)(3)](2+)-C-60 Langmuir-Blodgett films in situ at the air-water interface and exsitu on substrates

The amphiphilic nature of a [Ru(bpy)(3)](2+)-C-60 dyad, namely, a hydrophob ic fulleropyrrolidine core covalently linked to a hydrophilic [Ru(bpy)(3)]( 2+) chromophore, through a trioxyethylene spacer, secures a controllable tw o-dimensional crystal growth of the dyad molecules at the air-water interfa ce. The existence of a truly monolayered structure was confirmed by means o f surface pressure (II) versus surface area (A) isotherms and as well as by Brewster angle microscopy. A limiting area of 117 Angstrom(2)/molecule for dyad 2 is in satisfactory agreement with that reported for pristine C-60 ( 93 Angstrom(2)/molecule). Brewster angle microscopy reveals, upon compressi on of the monolayer to the point of collapse, a phase transition. In partic ular, the dyad monolayer transforms into threadlike fibers, which align per pendicular to the compression direction. Two-dimensional AFM images suggest that the dyad fibers are composed of close-packed several hundred mu m lon g and 1.0 +/- 0.2 mu m wide clusters, which in turn consist of nanosized dy ad clusters, with diameters of 100 +/- 20 nm.