Publication Details (including relevant citation information):
Ogunrinde, Ayowale, Hipps, K. W., Scudiero, L. Langmuir 2006 22 (13) 5697-5701
Abstract: The adsorption of nickel(II) octaethylporphyrin (NiOEP) from benzene and chloroform solutions on highly ordered pyrolytic graphite (HOPG) was investigated with a scanning tunneling microscope (STM) operated in ambient conditions. STM images show that NiOEP self-assembles on the graphite surface and that the molecules lie flat and form 2D lattices with spacings of 1.58 ± 0.03 nm by 1.46 ± 0.06 nm with a lattice angle of 69° ± 4° averaged over both solvents. We were unable to eliminate the possibility that one unit cell distance is twice the above-reported distance. The corresponding molecular packing density, 4.5 ± 0.3 × 1013 molecules/cm2, was essentially the same for benzene and chloroform solution deposition. These results differ somewhat from the structure revealed by high-resolution STM images of NiOEP on Au (111). The lack of apparent height (image intensity) in the constant current STM image of the alkane region of alkane-substituted metal porphyrins is attributed to a combination of changes in alkane configuration relative to the ring and associated changes in electronic coupling with **** and LUMO.
Address (URL): http://dx.doi.org/10.1021/la060233p