Group 14 Substitution as Modulator of Single Molecular Conductance in Highly Conductive Planarized...

The heavier Group 14 elements Si and Ge are known for their superior conductance performance over carbon in σ-channel-dominated molecular wires. Only a few studies have, however, explored their potential as C substitutes in wires with π-dominated conductance channels. We report a series of diarylamine (DA)-terminated π-conjugated wires, where C, Si, and Ge bridging atoms planarize a phenylene-vinylene linker. We find a slight impact on the conductance performance that deviates from the ordering according to atomic mass, with Si achieving a 20-30% higher conductance compared to Ge and C. DA oxidation increases conductance by 2 orders of magnitude and mitigates heteroatom-induced variations. Furthermore, the meta isomer of the Si analogue was synthesized in an effort to increase heteroatom participation in the conductance channel, revealing increased sensitivity to atomic substitution and considerable conductance at a 0.5 V bias.