2-DIMENSIONAL SELF-ASSEMBLY OF DNA-BASE MOLECULES ON CU(111) SURFACES

We present scanning tunneling microscope images of the self-assembled nucleic-acid base molecules on the surfaces of Cu(111). The images rev eal that the chemical inertness of the Cu(111) substrate allows the mo lecules to diffuse over the surface to self-assemble themselves sponta neously into their own unique structure: adenine into one-dimensional (1D) molecular chains, thymine into 2D islands, guanine into 2D square lattices, and cytosine into 1D zig-zag molecule-cluster networks. We find that molecular orbital calculations reproduce some of the observe d self-assembly, and suggest that base-base interaction induced by hyd rogen bonding is essential to this phenomenon.