Preparation of Azobenzenealkanethiols for Self-Assembled Monolayers with Photoswitchable Properties

A series of azobenzenealkanethiol compounds with the structure p-RC6H4N=NC6H4(CH2)(n)SH(n = 3, 4) was synthesized using a divergent strategy with the two anilines H2NC6H4(CH2)(n)SAc as central compounds. This strategy provides fast access to a broad variety of the respective azobenzenethiols without (note!) an oxygen atom in the alkyl chain, thus permitting the self-assembly of these compounds onto gold in a predictable conformation, also taking advantage of the previously found odd-even effect in aromatic-aliphatic hybrid systems. Initial experiments indicate that all of these molecules indeed form dense monolayers, in which the orientation of the azobenzene unit is determined by the number of methylene groups in the aliphatic part of the molecules.