STM INVESTIGATIONS ON BRIDGED MACROCYCLIC METAL-COMPLEXES

The non-crystallizable bridged phthalocyaninatoiron complexes, [(tBu)4 PcFe(dib)]n (1) and [(tBu)4PcFe(me2pyNC)]n (2), were spread onto highl y oriented pyrolytic graphite and imaged using scanning tunnelling mic roscopy in air. Dominating parallel arrangements of the oligomeric mol ecules in bundles of two to five stacks have been found. The individua l building blocks, namely, the macrocycles (tBu)4PcFe and the bridging ligands 1,4-diisocynobenzene (dib) and 4-isocyano-3,5-dimethylpyridin e (me2pyNC), however, could not be resolved. Possible reasons include the non-pronounced molecular structure, a non-perfect solvent removal and the strong electric force of the tip to the weakly bonded molecule . The width (about 15 angstrom) and the length (80 to 450 angstrom) of the single oligomer stacks agree well with the structure model and, w ith respect to the chain lengths, the results of non-spatially resolvi ng measuring methods.