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

Abstract

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 <i>meta</i> 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.