Abstract: The influence of substituents on electron transport through single-molecule mercapto-azobenzene were investigated by using density functional theory (DFT) B3LYP/6-31G** to calculate the geometry and electronic structure changes. With the introduction of electron-withdrawing group (—COOH or —NO2) into single-molecule mercapto-azobenzene, the calculation results showed that the electron transporting stability increased, the delocalization effect of LUMO rose, the reactivity of sulfur atomincreased and HOMO-LUMOgap (HLG) decreased evidently; which led to a decrease in the energy gap of electron transport and a rise in the electron transport abilities. Comparing molecular ion with its molecule, it could be found that the HLG of the molecular ion decreased further, S—Au bond was easier to form, and electron transfer took placemore easily through the systemof metal-molecule-metal.

Key words: Mercapto-azobenzene, Electron transport, Density functional theory, Electron Structure