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 (H2T3py)
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 H2T3py 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
°C, are about 100 °C higher than those of the single building
blocks.