Conductance of a single molecule anchored by an isocyanide substituent to gold electrodes

Abstract

The effect of anchoring group on the electrical conductance of a single molecule bridging two Au electrodes was studied using disubstituted [isocyanide (CN–), thiol (S–), or cyanide (NC–)] benzene. The conductance of a single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom (junction with the Au–CN bond) was 3×10−3G0(=2e2∕h). The value was comparable to 4×10−3G0 of a single Au/1,4-benzenedithiol/Au junction with the Au–S bond. The Au/1,4-dicyanobenzene/Au molecular junction with the Au–NC bond did not show well-defined conductance values. The metal-molecule bond strength was estimated by the distance over which the molecular junction was stretched before breakdown. The stretched length of the molecular junction with the Au–CN bond was comparable to that of the Au junction, indicating that the Au–CN bond was stronger than the Au–Au bond.