Discrete metallosupramolecular platforms with a high degree of symmetry and intricacy have been extensively investigated owing to their promising applications in a variety of fields. However, their preparative paradigms are commonly confined by the use of simple coordination modes involving the assemblies of metal ions and ligands (“primary” assembly) or multinuclear metal clusters and multifunctional ligands (“secondary” assembly). Therefore, the structural diversity, symmetry, and complexity of targeted discrete architectures achieved by these conventional assembly fashions, to some extent, are still limited. We report a strategy to achieve discrete molecular platforms featuring a high level of structural hierarchy through a multiple-assembly process. A cobalt (Co) supramolecular triple-stranded helicate-based discrete molecular cage, [[Co8(PDA)6(tbu-PTA)3(DMF)4(H2O)2]6-[Co(H2O)3]4] (1) (PDA = 2,6-pyridinedicarboxylate, tbu-PTA = 5-tert-butyl isophthalate, DMF = dimethylformamide), was successfully synthesized through the “tertiary” assembly concepts. The solid-state structure of 1 shows that it is composed of six triple-stranded helicates, which is generated through the secondary assembly of Co-based clusters (primary assembly), interconnected through four linking Co(II) species. Complex 1 is an unusual example of a highly symmetric discrete molecular architecture resulting from the coordination-driven assembly of in-situ generated supramolecular modules. Complex 1 showed much higher and more selective CO2 uptake properties compared with the separate supramolecular modules (triple-stranded helicates) and other discrete molecular platforms.

Cobalt supramolecular triple-stranded helicate-based discrete molecular cage

253rd National Meeting (2017)

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