Stacking Interactions Drive Selective Self-Assembly and Self-Sorting of Pyrene-Based M^II₄L₆ Architectures

Subcomponent self-assembly of two isomeric bis­(3-aminophenyl)­pyrenes, 2-formylpyridine and the metal ions Fe^II, Co^II, and Zn^II led to the formation of two previously unidentified structure types: a C₂-symmetric M^II₄L₆ assembly with meridionally coordinated metal centers, and a C₃-symmetric self-included M^II₄L₆ 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 C_2h-symmetric M^II₂L₂ 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 M^II₄L₄L′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 M^II₄L₆ and M^II₄L′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.