Surface assembly of porphyrin nanorods with one-dimensional zinc–oxygen spinal cords

We have built long-range ordered, one-dimensional (1D) nanorods by self-assembly of zinc porphyrin derivatives through axial coordination with oxygenated ligands on different noble-metal surfaces. The structures were studied by a combination of Variable-Temperature Scanning-Tunnelling Microscopy (VT-STM), X-Ray Photoelectron Spectroscopy (XPS) and Density Functional Theory (DFT) calculations. The combined morphological, chemical and theoretical results demonstrate that the zinc atoms at neighbouring porphyrin molecules are coordinatively linked through oxygen-containing species, most probably water, leading to an adsorption geometry in which the porphyrin planes are perpendicular to the substrate plane, and the polymers are lying parallel to the surface.