Rational design of outer‐expanded purine analogues as building blocks of DNA‐based nanowires with enhanced electronic properties

Abstract

Due to the fact that natural DNA may lack sufficient conductance for direct application in molecular electronics, a novel design of outer‐expanded purine analogues was proposed by incorporating an aromatic ring at the N7‐C8 site into natural G and A bases from the outside. The effect of the outer‐expansion modification on electronic properties of DNA was investigated by density functional theory and molecular dynamics. The analyses revealed that these purine analogues not only preserve the same sizes of natural purine bases, thus avoiding distortions of DNA skeleton induced by the normal ring‐inner‐expansion modification, but also keep the selectivity of pairing with their natural counterpart C and T bases. More importantly, their electronic properties are enhanced, indicated by the narrowed HOMO–LUMO gaps, the lowered ionization potentials and the improved ultraviolet absorption spectra. This work may provide helpful information for designing of artificial bases as promising building blocks of biomolecular nanowires. © 2014 Wiley Periodicals, Inc.