Intermolecular Communication in a Supramolecular Assembly of Porphyrins and Phthalocyanines

Programmable construction of a multiple molecular system is the best measure for bringing out the integrated properties evolved from the intermolecular communications in the molecular assemblies. Especially, controlling sequential and spatial arrangements of building components in the molecular array is crucial for developing novel functions of the designer nanoarchitecture. Since organized assemblies of porphyrins and phthalocyanines are promising for generating higher functionalized systems, we have recently reported the supramolecular arrays in which a porphyrin and a phthalocyanine are connected by four-fold rotaxanes [1-4] and sequential and spatial organization of metalloporphyrins inside a peptide duplex [5].

In this paper, we will present construction of the suplamolecular arrays of a metallo-porphyrin and a metallo-phthalocyanine through four-fold rotaxane formation between a tetradactyl porphyrin with alkylammmonium moieties and a phthalocyanine bearing four crown ethers (Figure 1a) and significant electronic communications between the metal complexes (Figure 1b). Since synthetic strategy for the rotaxane is applicable to pre- and post-metallation of both porphyrin and phthalocyanine centers, the four-fold rotaxane framework is suitable for homo- and hetero-assemblage of metal ions. In a homo-dinuclear Cu²⁺ complex of the four-fold rotaxane, the Cu²⁺-porphyrin and the Cu²⁺-phthalocyanine showed a switching behavior in the spin–spin interaction through change of the spatial distance between the two metal centers induced by protonation and deprotonation.

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