Two
molecular metalla-knots containing over 500 non-hydrogen atoms
(especially 16 RhIII ions) and one molecular Borromean
ring were obtained in high yields facilitated by multiple intermolecular
interactions between their components. The syntheses rely on the strategic
selection of the nonlinear dipyridyl ligand 2,7-di(pyridin-4-yl)-9H-fluorene (L
1
) as
precursor, and the structures of the assemblies were confirmed by
detailed X-ray crystallographic analysis. Subsequently, replacing L
1
with the bulkier ligand 4,4′-(9,9-dimethyl-9H-fluorene-2,7-diyl)dipyridine (L
2
) led to the formation of three tetranuclear metallocycles
in high yields on account of the weakened π–π stacking
interactions between the naphthacene/anthracene and fluorene moieties,
which in turn confirmed the significance of stacking interactions
in the construction of the molecular 818 metalla-knots
and the molecular Borromean ring.