The codriven assembly of molecular metalla-links ([Formula: see text], [Formula: see text]) and metalla-knots ([Formula: see text], [Formula: see text]) via coordination and noncovalent interactions.
Proc Natl Acad Sci U S A
; 121(27): e2407570121, 2024 Jul 02.
Article
em En
| MEDLINE
| ID: mdl-38941275
ABSTRACT
Although mechanically interlocked molecules (MIMs) display unique properties and functions associated with their intricate connectivity, limited assembly strategies are available for their synthesis. Herein, we presented a synergistic assembly strategy based on coordination and noncovalent interactions (π-π stacking and CHâ¯π interactions) to selectively synthesize molecular closed three-link chains ([Formula see text] links), highly entangled figure-eight knots ([Formula see text] knots), trefoil knot ([Formula see text] knot), and Borromean ring ([Formula see text] link). [Formula see text] links can be created by the strategic assembly of nonlinear multicurved ligands incorporating a furan or phenyl group with the long binuclear half-sandwich organometallic Cp*RhIII (Cp* = η5-pentamethylcyclopentadienyl) clip. However, utilizing much shorter binuclear Cp*RhIII units for union with the 2,6-naphthyl-containing ligand led to a [Formula see text] knot because of the increased π-π stacking interactions between four consecutive stacked layers and CHâ¯π interactions. Weakening such π-π stacking interactions resulted in a [Formula see text] knot. The universality of this synergistic assembly strategy for building [Formula see text] knots was verified by utilizing a 1,5-naphthyl-containing ligand. Quantitative conversion between the [Formula see text] knot and the simple macrocycle species was accomplished by adjusting the concentrations monitored by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Furthermore, increasing the stiff π-conjugated area of the binuclear unit afforded molecular Borromean ring, and this topology is a topological isomer of the [Formula see text] link. These artificial metalla-links and metalla-knots were confirmed by single-crystal X-ray diffraction, NMR and ESI-MS. The results offer a potent strategy for building higher-order MIMs and emphasize the critical role that noncovalent interactions play in creating sophisticated topologies.
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Ano de publicação:
2024
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Article