Self-assembled porphyrin-based cage complexes, M11L6 (M = ZnII, CdII), with inner coordination sites in their crystal structure

Abstract

Herein we report self-assembled metallo-cage complexes, M11(L1)6 (M = ZnII, CdII), formed from 4-fold-symmetric ZnII-porphyrin-centered tetrakis-meso-(5¤-methyl-2,2¤-bipyridyl) ligands. The structures of these two D3-symmetric cages have been characterized by 1D and 2D NMR, ESI-MS, and XRD analyses. A common structural feature of these complexes is their inner molecular binding site at the axial position of each square-pyramidal ZnII-porphyrin in the crystal structure, which would provide a method to place molecular coordination sites inside or outside the cage complex with the minimum chemical modification.