Porphyrinphosphonate fibers on mica and molecular rows on graphite

meso-Tetra(phenyl-p-phosphonate) porphyrin forms rigid and well-separated fibers of monomolecular thickness (2.8 nm) and lengths of several micrometers on mica at pH 13 (octasodium salt). The formation of these fibers could be observed directly by tapping mode scanning force microscopy (SFM) and was induced by capillary forces. Normal height images or images with a topographical inversion were observed depending on the distance of the SFM tip. Amplitude-distance curves indicated that a stable meniscus was formed on hydrophilic surface areas below a tip-sample separation of 20 mn. The meniscus let the original nanorods appear as ditches in the mica surface and enabled rearrangements. A partly protonated form of the same porphyrin (pH 11.5) gave rows of flat-lying porphyrins on graphite, which appear with molecular resolution in SFM images as well as two-dimensional platelets of monomolecular thickness.