Journal of the American Chemical Society, Vol.137, No.45, 14502-14512, 2015
Stacking Interactions Drive Selective Self-Assembly and Self-Sorting of Pyrene-Based (M4L6)-L-II 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 C-2-symmetric (M4L6)-L-II assembly with meridionally coordinated metal centers, and a C-3-symmetric self-included (M4L6)-L-II assembly with facially coordinated metal centers. In both structures the meta linkages within the ligands facilitate pi-stacking between the pyrene panels of the ligands. A C-2-symmetric (M2L2)-L-II box was also obtained, which was observed to selectively bind electron-deficient aromatic guests between two parallel pyrene subunits. Similar donoracceptor interactions drove the selective self-assembly of a singular (M4L4L)-L-II'(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 (M4L6)-L-II and (M4L)-L-II'(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.