Effect of Tether Conductivity on the Efficiency of Photoisomerization of Azobenzene-Functionalized Molecules on Au{111}.

We establish the role of tether conductivity on the photoisomerization of azobenzene-functionalized molecules assembled as isolated single molecules in well-defined decanethiolate self-assembled monolayer matrices on Au{111}. We designed the molecules so as to tune the conductivity of the tethers that separate the functional moiety from the underlying Au substrate. By employing surface-enhanced Raman spectroscopy, time-course measurements of surfaces assembled with azobenzene functionalized with different tether conductivities were independently studied under constant UV light illumination. The decay constants from the analyses reveal that photoisomerization on the Au{111} surface is reduced when the conductivity of the tether is increased. Experimental results are compared with density functional theory calculations performed on single molecules attached to Au clusters.