Double Rotors with Fluxional Axles: Domino Rotation and Azide–Alkyne Huisgen Cycloaddition Catalysis

Abstract

The simple preparation of the multicomponent devices [Cu4(A)2]4+ and [Cu2(A)(B)]2+, both rotors with fluxional axles undergoing domino rotation, highlights the potential of self-sorting. The concept of domino rotation requires the interconversion of axle and rotator, allowing the spatiotemporal decoupling of two degenerate exchange processes in [Cu4(A)2]4+ occurring at 142 kHz. Addition of two equiv of B to rotor [Cu4(A)2]4+ afforded the heteromeric two-axle rotor [Cu2(A)(B)]2+ with two distinct exchange processes (64.0 kHz and 0.55 Hz). The motion requiring a pyridine→zinc porphyrin bond cleavage is 1.2×105 times faster than that operating via a terpyridine→[Cu(phenAr2)]+ rupture. Finally, both rotors are catalysts due to their copper(I) content. The fast domino rotor (142 kHz) was shown to suppress product inhibition in the catalysis of the azide–alkyne Huisgen cycloaddition.