The single-molecule conductance of DNA was found to increase by over four fold upon intercalation, while the conductance nearly unaltered upon groove-binding. These effects are interpreted on the basis of the electronic interaction of the DNA-binding molecules with the stacked DNA bases.
Single-molecule devices attract much interest in the development of nanoscale electronics.A lthough av ariety of functional single molecules for single-molecule electronics have been developed, there still remains the need to implement sophisticated functionalization towardp ractical applications. Given its superior functionality encountered in macroscopic materials,apolymer could be au seful building blocki nt he single-molecule devices.T herefore,amolecular junction composed of polymer has nowb een created. Furthermore,a n automated algorithm was developed to quantitatively analyze the tunneling current through the junction. Quantitative analysis revealed that the polymer junction exhibits ah igher formation probability and longer lifetime than its monomer counterpart. These results suggest that the polymer provides au nique opportunity to design both stable and highly functional molecular devices for nanoelectronics.
The electrical properties of DNA have been extensively investigated within the field of molecular electronics. Previous studies on this topic primarily focused on the transport phenomena in the static structure at thermodynamic equilibria. Consequently, the properties of higher-order structures of DNA and their structural changes associated with the design of single-molecule electronic devices have not been fully studied so far. This stems from the limitation that only extremely short DNA is available for electrical measurements, since the single-molecule conductance decreases sharply with the increase in the molecular length. Here, we report a DNA zipper configuration to form a single-molecule junction. The duplex is accommodated in a nanogap between metal electrodes in a configuration where the duplex is perpendicular to the nanogap axis. Electrical measurements reveal that the single-molecule junction of the 90-mer DNA zipper exhibits high conductance due to the delocalized π system. Moreover, we find an attractive self-restoring capability that the single-molecule junction can be repeatedly formed without full structural breakdown even after electrical failure. The DNA zipping strategy presented here provides a basis for novel designs of single-molecule junctions.
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