Redox-responsive porphyrin-based molecular tweezers.

Pinching pacman! Switching between the "open" and "closed" arrangements of pacman-like bisporphyrin architectures can be achieved by redox control of noncovalent interactions (see figure). The open/close molecular motion, triggered by reduction of π-dimerizable bipyridinium units, has been shown to allow the complexation of a bidentate ligand pinched between both metalloporphyrins.