Hexakis (pyridyl-functionalised porphyrinato)benzene as a building block for the construction of multi-chromophoric arrays

A new hexakis porphyrinato benzene compound has been synthesised and studied by different spectroscopic techniques. It consists of 6 porphyrin moieties which are covalently attached to one central benzene core. Each porphyrin contains 3 pyridyl functions, making a total of 18 potential coordination sites. The structure is a multi-porphyrin array in its own right but can be extended further by means of metal-directed self-assembly. This was demonstrated with the help of a platinum diimine complex substituted with two dodecyl-tails. The pyridine-functionalised hexa-porphyrin was found to bind only 6 instead of the expected 18 platinum complexes, which is ascribed to steric hindrance. Electron microscopy studies reveal that both the pyridine-functionalised hexaporphyrin and its metal-coordination product form well-defined ring structures of micrometer size on solid supports.