K W Hipps - Organization of Vanadyl and Metal-Free Tetraphenoxyphthalocyanine Complexes on Highly Oriented Pyrolytic Graphite in the Presence of Paraffinic Solvents: A STM Study

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  Mazur, Ursula, Hipps, K. W., Riechers, Shawn L. The Journal   of Physical Chemistry C 2008 112  (51) 20347-20356

  Abstract: Scanning tunneling microscopy (STM) is   employed to demonstrate that the presence of the vanadyl ion   (VO2+) in the 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine   complex (VOPcPhO) has a pronounced effect on the organization of   the complex at the highly oriented pyrolytic graphite   (HOPG)−n-alkyl benzene (n = 6, 7, 8, and 10) interface. VOPcPhO   forms at least three different stable architectures, as compared   to only one type of structure resulting from the adsorption of   the metal-free tetraphenoxyphthalocyanine analog (H2PcPhO) on   HOPG under conditions similar to VOPcPhO. All three observed   VOPcPhO monolayer structures have high packing density and are   commensurate with the underlying graphite lattice, whereas   H2PcPhO forms a lower packing density incommensurate adlayer. The   VOPcPhO structures display a small rectangular unit cell (1   molecule/cell) with lattice vector lengths of 1.28 and 1.48 nm, a   larger rectangular unit cell (6 molecules/cell) with lattice   vector lengths of 4.43 nm 2.98 nm, and an oblique unit cell (2   molecules/cell and α = 84.7°) with lattice vector lengths of 1.48   and 2.99 nm. As a second layer begins to form, it preferentially   adds to the large unit cell, keeping those lattice parameters,   but with only four molecules per cell. The H2PcPhO adlayer   achieves an oblique unit cell (α = 74° and 1 molecule/cell) with   1.58 and 1.68 nm length lattice vectors. On the basis of combined   experimental results and theoretical calculations, we propose   models for the observed molecular organizations.

  Address (URL): http://dx.doi.org/10.1021/jp805684z