Structure-property relationships in molecular wires

Molecular electrical conductivities between gold electrodes have been measured at the single molecule level through a variety of systems. The results show that the aromaticity of molecules is partly disrupted by passage of electricity, leading to increased resistance. The possibility of the opposite effect resulting from the disruption of antiaromaticity was explored in biphenylene derivatives. When gold atoms terminate benzene or polymethylene molecules they incorporate into the electrodes, greatly diminishing the resistance from other terminating atoms. In paracyclophanes with two, three, and four benzenes in stacks the gold electrodes can directly contact them, and thus measure conductivity directly through the stacks.