Stacking Interactions Drive Selective Self-Assembly and Self-Sorting of Pyrene-Based MII4L6 Architectures

Subcomponent self-assembly of two isomeric bis­(3-aminophenyl)­pyrenes, 2-formylpyridine and the metal ions FeII, CoII, and ZnII led to the formation of two previously unidentified structure types: a C2-symmetric MII4L6 assembly with meridionally coordinated metal centers, and a C3-symmetric self-included MII4L6 assembly with facially coordinated metal centers. In both structures the meta linkages within the ligands facilitate π-stacking between the pyrene panels of the ligands. A C2h-symmetric MII2L2 box was also obtained, which was observed to selectively bind electron-deficient aromatic guests between two parallel pyrene subunits. Similar donor–acceptor interactions drove the selective self-assembly of a singular MII4L4L′2 architecture incorporating both a pyrene-containing diamine and an electron-deficient NDI-based diamine. This heteroleptic architecture was shown to be thermodynamically favored over the corresponding homoleptic MII4L6 and MII4L′6 complexes, which were nonetheless stable in each others’ absence. By contrast, an isomeric pyrene-based diamine was observed to undergo narcissistic self-sorting in the presence of the NDI-based diamine.