We hypothesize that the carbon atom at the terminal para position in amino-p-terphenyl derivatives PPP, PPM, and PMP forms a direct Au-C covalent linkage due to an oxidation event at the metal electrode, forming a terminal anchor that completes the circuit and leads to the high conductance pathway (Figure ). The absence of the high conductance feature in MPP is consistent with the hypothesis that the methyl group at the terminal para position inhibits the interaction between the molecule and the gold electrode, preventing the formation of the Au-C linkage. However, the para position remains available for binding in PPM and PMP, but the substituent groups on these molecules disrupt their symmetry, which disfavors the formation of the quinoidal resonance structure. PMP contains a methyl substituent on the central ring, which alters the torsional angles and hinders the formation of the planar quinoidal resonance form, resulting in a weak high conductance feature compared to PPP.