Single-molecule electrical conduction studies are used to evaluate how the molecular linking unit influences the tunneling efficiency in metal -molecule -metal (m-M-m) junctions. This work uses conducting-probe atomic force microscopy (CP-AFM) to compare the molecular conduction of two pi-bonded molecules: one with a single thiol linker, and another with a conjugated double thiol linker at both ends of the molecules. The results demonstrate that the molecule with conjugated double thiol linkers displays higher conduction in gold -molecule -gold junctions than nonconjugated single thiol-gold contacts.