Conductance of alkyl-based molecules with one, two and three chains measured by electrochemical STM break junction

In this communication, the conductance of molecules with one, two and three parallel alkyl chains was measured by electrochemical STM break junction approach. The conductance ratio between trans-1,4-cyclohexanedicarboxylic acid (M2) and 1,4-butanedicarboxylic acid (M1) is 2.4 for Ag and 2.5 for Cu electrodes. This may be contributed to the constructive quantum interference in M2 molecule with two parallel chains. However, the conductance of bicyclo[2.2.2]octane-1,4-dicarboxylic acid (M3) with three parallel alkyl chains is smaller than that of M2, which may arise from the destructive quantum interference when electron transport through M3. The current work reveals the interference effect in the alkyl molecule, and proposes a feasible way to design high performable molecule wires. (C) 2014 Elsevier B.V. All rights reserved.