NANO LETTERS
Palladium Wire-Shaped Nanoparticles from Single Synthetic Polycation Molecules
2002 Vol. 2, No. 8 881-885
Anton Kiriy, Sergiy Minko,* Ganna Gorodyska, and Manfred Stamm Institut fu¨ r Polymerforschung Dresden, Hohe Strasse 6, 01069 Dresden, Germany
Werner Jaeger Department of Water Born Polymers, Fraunhofer-Institut fu¨ r Angewandte Polymerforschung, Geiselbergstr. 69,14476 Golm, Germany Received May 3, 2002; Revised Manuscript Received May 29, 2002
ABSTRACT Here we described simple chemical route to fabricate wire-shaped metallic nanoparticles of about 5 nm in a diameter and of 1000 nm in a length from single synthetic polycations. The preparation is based on the deposition of Pd-clusters on single poly(methacryloyloxyethyl dimethylbenzylammonium chloride) molecules adsorbed on Si-wafers from aqueous solution. The length and the diameter of nanowires are determined by the length and the diameter of the underlying polymer chains.
Introduction. Due to the considerable success in modern supramolecular1 and polymer2 chemistry various molecular objects of different shapes and functionalities are available now. Using complimentary building blocks and employing chemical reactions or self-assembling methodology3 it is possible to design complicated structures at molecular level.4 These approaches provide the development of the modern field of molecular electronics.5 For the further miniaturization of electronic devices it would be a challenging task to develop simple methods to fabricate nanoparticles of dedicated shape and desired properties incorporated in a supermolecular construction assembled from single functional molecules. One-dimensional (1D) sequences of nanoparticles (nanowires) are important elements of the nanotechnology toolbox because they provide interconnects between functional devices and even can be used as elementary units of optoelectronic devices. They also have been attracting increasing attention due to unique optical,6 magnetic,7 and catalytic8 properties. Several routes have been developed for synthesis of metallic nanowires, including template synthesis,9 step-edge decoration,10 vapor-liquid-solid condensation,11 as well as several other wet chemical techniques based on reduction of metals in the presence of protecting polymers or surfactants.12 Template-based methods involve deposition of metals into cylindrical pores of a host material, so-called 1D nanotemplates, e.g., carbon nanotubes,13 rod-like micelles,14 etc. Recently, DNA has been successfully used as * Corresponding author:
[email protected]. 10.1021/nl025603i CCC: $22.00 Published on Web 06/14/2002
© 2002 American Chemical Society
a biotemplate for the fabrication of metallic nanowires from single molecules.15 The synthesis is based on a two-step procedure that involves binding of metals (Pd or Ag) to DNA followed by chemical reduction. This procedure results in 20-100 nm thick metallic wire-shaped particles, which are, however, much larger than 2 nm assumed for the diameter of a single DNA molecule. Vacuum evaporation was used to deposit gold on single extended DNA strands to produce wires of width
