Triply Stacked Heterogeneous Array of Porphyrins and Phthalocyanine through Stepwise Formation of a Fourfold Rotaxane and an Ionic Complex

We report the preparation and crystal structure of a triply stacked metal complex array in which a Cu-phthalocyanine is sandwiched between different Cu-porphyrins. The discrete heterogeneous assembly was prepared through formation of a fourfold rotaxane from a tetradactyl porphyrin with alkylammonium moieties and a phthalocyanine bearing four crown ethers and the subsequent formation of an ionic complex between the fourfold rotaxane and a tetraanionic porphyrin. The tetraanionic porphyrin, Cu-TPPS4-, is selectively bound to the fourfold rotaxane through cooperative pi-pi and ionic interactions. The crystal structure revealed the columnar stacked array of the three planar building components in a precise order and spatial arrangement that promote intermolecular electronic communication.