New Multicomponent Porous Architecture of Self-Assembled Porphyrins/Calixarenes Driven by Nickel Ions

A new multicomponent material with nanoporous structure has been synthesized by co-crystallization of a mixture of cationic meso-tetrakis(4-N-methylpyridyl)porphyrin (H2T4) and meso-tri(4-N-methylpyridyl)porphyrin (H(2)T(3)py) with polyanionic 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(hydroxylcarbonylmethoxy)calix[4]arene (C4TsTc) in the presence of Ni2+ ions. The structural analysis indicates that the overall architecture is assembled by interpenetrated two-dimensional (2D) meshes where the nodes are built up by a central tetracationic H2T4 porphyrin with arms hosted in sulphonated rims of four cavitands. The approximately 2D square network is formed by Ni2+ ions bridging the calixarene carboxylate rims in a tail-to-tail fashion. The central H2T4 stacks with two external H(2)T(3)py molecules having the neutral pyridine arm N-coordinated to Ni2+ ions. These metal centers interconnect the orthogonal 2D meshes by further coordination of calixarene-carboxylate groups. Self-organization of the new multicomponent material, featuring large channels (60% of volume accessible to solvent molecules) and potential readily accessible metal active sites, has been driven by both supramolecular host-guest recognition and coordinative assembly. The thermal behavior of native and nickel-containing crystals was studied by hot stage microscopy and differential scanning calorimetry. The decomposition temperatures of the multicomponent materials, 465-470 degrees C, are about 100 degrees C higher than those of the single building blocks.