Nanoscale Engineering of Molecular Porphyrin Wires on Insulating Surfaces

Ordered nanostructures of meso-(4-cyanophenyl)-substituted Zn(II) porphyrin molecules are formed along step edges and specific directions of KBr(001). Short and long molecular wires, ringlike structures, and oriented multiwires (see image) are observed by high-resolution noncontact atomic force microscopy on insulating surfaces. Intermolecular distances of 0.5–0.6 nm indicate π–π stacking of the porphyrin rings, which is comparable to natural light-harvesting structures.