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Synthesis of interlocked supramolecular cages has been a growing field of interest due to their structural diversity. Herein, we report the template-free synthesis of a Ru(II) triply interlocked 2 catenane using coordination-driven self-assembly. The self-assembly of a triazine-based tripyridyl donor L (2,4,6-tris(5-(pyridin-4-yl)thiophen-3-yl)-1,3,5-triazine) with a dinuclear Ru(II) acceptor M (Ru 2 (dhnq)(η 6 - p -cymene) 2 )(CF 3 SO 3 ) 2 ) yielded two distinct structures depending on the solvent and concentration. In methanol, a triply interlocked metalla 2 catenane ( MC2 ) was formed, whereas in nitromethane, a non-interlocked cage ( MC1 ) was obtained. The non-interlocked cage MC1 was gradually converted to MC2 in nitromethane by the increase in the concentration of cage MC1 from 0.5 to 9 mM. The interlocked cage ( MC2 ) was stable after formation and was unaffected by the change in concentration. Notably, the free cage ( MC1 ) exhibited host–guest interactions with polycyclic aromatic aldehydes, stabilizing the non-interlocked structure even at higher concentrations. In contrast, the triply interlocked 2 catenane ( MC2 ) remains stable due to self-penetration and does not encapsulate guest molecules. This work showcases the stimuli-induced irreversible structural transformation of a triangular prismatic cage to its triply interlocked 2 catenane by employing metal–ligand coordination chemistry.
Ali et al. (Mon,) studied this question.