DABCO as a Dynamic Hinge between Cofacial Porphyrin Panels and Its Tumbling inside a Supramolecular Cavity

The heteroleptic supramolecular double-decker porphyrin 1 was synthesized with DABCO as a guest between two cofacial porphyrin units as characterized by 1H NMR and ESI-MS. While DABCO is not seen to tumble inside the cavity, even at higher temperatures (80 °C), such motion was triggered upon addition of various coordinating ligands (quinuclidine, 4-bromopyridine, or excess of DABCO). Different stoichiometric amounts were needed depending on the n donor quality of the added ligands to initiate tumbling of the “inside” DABCO. As demonstrated in an example with excess DABCO, the tumbling was stopped by lowering the temperature to −50 °C.