The nanomechanical switch 1 with its three orthogonal binding motifs-the zinc(II) porphyrin, azaterpyridine, and shielded phenanthroline binding station-is quantitatively and reversibly toggled back and forth between four different switching states by means of addition and removal of appropriate metal-ion inputs. Two of the four switching stages are able to initiate catalytic transformations (ON1, ON2), while the two others shut down any reaction (OFF1, OFF2). Thus, in a cyclic four-state switching process the sequential transformation A+B+C→AB+C→ABC can be controlled, which proceeds stepwise along the switching states OFF1→ON1 (click reaction: A+B→AB)→OFF2→ON2 (Michael addition: AB+C→ABC)→OFF1. Two consecutive cycles of the sequential catalysis were realized without loss in activity in a reaction system with eleven different components.

The present work demonstrates the operation of a reversible supramolecular gate, i.e., an ensemble of various components linked by chemical communication, which is triggered by stoichiometric chemical inputs and by obeying the AND truth table delivers a stoichiometric chemical signal. The output triggers a series of events that finally set up a catalytic process. In detail, a three-component AND gate, composed of two distinct nanoswitches, a copper-loaded and an unloaded one {= state (0,0)}, was actuated with stoichiometric amounts of two inputs (IN-1 = Zn2+, IN-2 = Hg2+) generating copper­(I) ions as output in state (1,1). The utility of this information processing was highlighted by using the copper­(I) output for triggering the self-assembly of the four-component rotor ROT-2 through metal translocation. In the presence of suitable reactants, ROT-2 acted as a catalytic machinery catalyzing a click reaction (= signal amplification). Verification of the functioning of the AND gate in a mixture of 12 components was thus accomplished by monitoring formation of the click product. Due to the stoichiometric design, the gate was reset to state (0,0) by adding hexacyclen and reactivated by adding inputs IN-1 and IN-2 alike in the first cycle.

We describe a electrochemically driven molecular shuttle, in which shuttling takes place by means of fullerene radical-anion recognition that results in a very low operation potential (E(1/2) =-0.580 V vs. decamethylferrocene). This has been achieved by introducing positive charges on the macrocycle, which strengthen the existing π-π interactions between the macrocycle and the electrogenerated fullerene radical anion by means of an electrostatic component. In addition, the synthesis of such a molecular shuttle has been accomplished by developing a new synthetic approach that exploits the controlled translocation of the macrocycle as a selective protecting group.

NetState I of the communication-catalysis protocol is defined by a 1 : 1 mixture of the nanoswitches [Cu(1)] and 2. Upon one-electron oxidation at the ferrocenyl unit of the switch [Cu(1)], copper(i) ions are released that after translocation toggle nanoswitch 2 → [Cu(2)] (NetState II) within 4 min. NetState I was fully reset within 1 min by reduction of 1+ → 1. Running this redox-triggered switching protocol in the presence of 4-nitrobenzaldehyde, diethyl malonate and piperidine (catalyst) allows toggling of a catalyzed Knoevenagel addition from ON to OFF and back to ON.