A platinum-linked porphyrin trimer and a complementary aluminium tris[3-(4-pyridyl)acetylacetonate] guest

Abstract

A cyclic trimeric porphyrin host has been synthesised with alkyne–platinum–alkyne linkages; binding of the octahedral aluminium tris[3-(4-pyridyl)acetylacetonate] guest ligand into the complementary cavity of the host induces an asymmetry which is readily detected by NMR spectroscopy. The ligand complementarity unambiguously establishes the structure of this complex artificial receptor, but did not lead to an effective templated synthesis. A platinum-linked tetramer was also tentatively identified, but the absence of a suitably complementary ligand reduces the confidence that can be placed in this larger, and highly flexible, structure. These results demonstrate the strengths, and limitations, of metal coordination chemistry for assembling supramolecular architectures.