In State-I, a mixture comprising a DABCO-bridged tris(zinc-porphyrin) double decker and a free biped (=slider), catalysis was OFF. Acid addition (TFA or Di-Stefano fuel acid) to State-I liberated DABCO-H + while generating a highly dynamic slider-on-deck device (State-II). The released DABCO-H + acted as a base organocatalyst for a Knoevenagel reaction (catalysis ON). The system was reversed to State-I (catalysis OFF) by reducing the acidity in the system (by adding DBU or via the fuel-derived base).
A dynamic silver(I)-loaded [2]rotaxane shuttle (k 298 = 135 kHz) was converted allosterically into a conformationally restricted [2]rotaxane due to the creation of a bulky imine in the center of the axle component. Only the dynamic silver(I)-loaded [2]rotaxane was able to catalyze a 6-endo-cyclization reaction, whereas the static one was catalytically quiet. The mechanism of catalyst deactivation was elucidated.
Boolean operations with multiple catalysts as output
are yet unknown
using molecular logic. The issue is solved using a two-component ensemble,
composed of a receptor and rotaxane, which acts as a three-input AND
gate with a dual catalytic output. Actuation of the ensemble gate
by the stoichiometric addition of metal ions (Ag+ and Cd2+) and 2,2,2-trifluoroacetic acid generated in the (1,1,1)
truth table state a catalyst duo that synergistically enabled a three-step
reaction, furnishing a dihydroisoquinoline as the output of a three-input
logic AND gate operation.
The heteroleptic multi-component double slider-on-deck system DS3 exhibits tight coupling of motional speed of two distinct nano-circular sliders (k 298 = 77 and 41 kHz) despite a 2.2 nm separation. In comparison, the single sliders in DS1 and DS2 move at vastly different speed (k 298 = 1.1 vs. 350 kHz). Synchronization of the motions in DS3 remains even when one slows the movement of the faster slider using small molecular brake pads. In contrast to the individual DS1 and DS2 systems, DS3 is a powerful catalyst for a twostep reaction by using the motion of both sliders to drive two catalytic processes.Synchronized motion in machines plays a ubiquitous role in nature to maintain life [1] by acting as energy transducer, [2] e.g. in the synthesis of ATP as a high-energy product and fuel by the multi-component F o F 1 -ATP synthase. Via efficient intercomponent communication, conformational changes in the F o subunit lead to cyclic structural changes in the F 1 unit which mediate a phase-shifted conversion of ADP and P i to ATP. [3] While motional speed in artificial machines has been a topic of great interest, [4][5][6][7][8][9] lately even in combination with catalysis, [10][11][12][13] we decided to pursue the concept of synchronized movement [14,15] in catalytic multicomponent machinery alike that in enzymes. Coupling of motion in individual selfassembled machines with multiple moving parts is very rarely reported, [16][17][18] and even less regarding distinct cata-lytic behavior. [19] Mostly coupling is achieved by geared motion in molecular arrangements. [20,21] Hence, the challenge to synchronize motion in a self-assembled multi-component machine and to exploit the coupled movement for double[*] V.
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