Self-assembled phthalocyanine derivatives on highly ordered pyrolytic graphite

A novel unsymmetrically substituted hydroxy-functionalized Zn(II) phthalocyanine (Pc) 1, bearing long aliphatic chains, namely, dodecyloxy units, has been designed and synthesized to investigate the influence of the terminal hydroxyl group on the formation of self-assembled nanostructures. The symmetric derivative, octadodecyloxy-Zn(II)Pc (2) has been also synthesized and used as reference compound for comparison purposes. The supramolecular organization of the Pcs has been carried out by spin-coating on a highly ordered pyrolytic graphite (HOPG) surface and has been investigated by atomic force microscopy (AFM) and scanning electron microscopy (STM). AFM and STM studies showed that unsymmetrically substituted hydroxy-functionalized Zn(II)Pc 1 gives rise to the formation of wire-like structures in different lengths from nanometer to micrometer scales, whereas in the case of the symmetrical Zn(II)Pc 2 the formation of the wires on HOPG was less pronounced.