Exchange Speed of Four-Component Nanorotors Correlates with Hammett Substituent Constants

Three distinct four-component supramolecular nanorotors were prepared, using, for the first time, bipyridine instead of phenanthroline stations in stator. Following our established self-sorting protocol to multicomponent nanodevices, self-assembled by mixing stator, rotators with various pyridine head groups, copper(I) ions and 1,4-diazabicyclo[2.2.2]octane (DABCO). Whereas exchange a vs. station did not entail significant changes rotational frequency, para-substituents at group rotator had drastic consequences on speed: 4-OMe (k298 = 35 kHz), 4-H 77 kHz) 4-NO2 843 kHz). The frequency (log k) showed an excellent linear correlation both Hammett substituent constants log K copper(I)–ligand interaction, proving that rotator–copper(I) bond cleavage is key determining factor rate-determining step.