Self-Assembly of a Functionalized Alkylated Isophthalic Acid at the Au(111)/Electrolyte Interface: Structure and Dynamics

The self-assembly of 5-(12-cyano-dodecyloxy)-isophthalic acid has been investigated at the Au(111)/aqueous electrolyte interface by means of electrochemical scanning tunneling microscopy (ECSTM). At potentials below the potential of zero charge (pzc), the molecules form a row type pattern, both on the reconstructed Au(111) surface (Au(111)-(22 x root 3)) as well as on the unreconstructed Au(111) surface (Au(111)-(1 x 1)). On both surfaces the isophthalic acid groups arrange commensurately along the root 3 direction of the surface. The cyano containing alkyl chains are interdigitated leading to the formation of cyano functional rows on the surface. The self-assembled layers show a strong dependency on the electrode potential. The potential induced phase transition of the organic layer, the lifting of the Au(I 11)-(22 x root 3) surface reconstruction in the presence of this molecular layer, as well as the growth of an ordered layer from a disordered phase, have been potentio-dynamically investigated.