Self-assembled guanine ribbons as wide-bandgap semiconductors

We present a first principle study about the stability and the electronic properties of a new biomolecular solid-state material, obtained by the self-assembling of guanine (G) molecules. We consider hydrogen-bonded planar ribbons in isolated and stacked configurations. These aggregates present electronic properties similar to inorganic wide-band gap semiconductors. The formation of Bloch-type orbitals is observed along the stacking direction, white it is negligible in the ribbon plane. Global band-like conduction may be affected by a dipole-Field which spontaneously arises along the ribbon axis. Our results indicate that G-ribbon assemblies are promising materials for biomolecular nanodevices, consistently with recent experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.