An Electrochemically and Thermally Switchable Donor–Acceptor [c2]Daisy Chain Rotaxane

Abstract

Although motor proteins are essential cellular components that carry out biological processes by converting chemical energy into mechanical motion, their functions have been difficult to mimic in artificial synthetic systems. Daisy chains are a class of rotaxanes which have been targeted to serve as artificial molecular machines because their mechanically interlocked architectures enable them to contract and expand linearly, in a manner that is reminiscent of the sarcomeres of muscle tissue. The scope of external stimuli that can be used to control the musclelike motions of daisy chains remains limited, however, because of the narrow range of supramolecular motifs that have been utilized in their templated synthesis. Reported herein is a cyclic daisy chain dimer based on π-associated donor-acceptor interactions, which can be actuated with either thermal or electrochemical stimuli. Molecular dynamics simulations have shown the daisy chain's mechanism of extension/contraction in the ground state in atomistic detail.

Controlling Motion at the Nanoscale: Rise of the Molecular Machines

“…[27][28][29] Catenanes are MIMs constructed from two or more interlocked macrocycles in a chain-like architecture that may be designed to adopt distinct, stable conformations with controllable rotary motions ( Figure 2a). Alternatively, rotaxanes, pseudorotaxanes, and their derivatives are molecules composed of a linear rod-like component threaded through a cyclic host; the exact position and orientation (station) of the relative components in the mechanically interlocked compound can be controlled by external stimuli.…”

Preise der Royal Society of Chemistry 2019

“…Voth entwickelt theoretische Verfahren für die Analyse der Struktur und Dynamik komplexer kondensierter Phasen. Er war unter den Autoren einer Angewandte‐Chemie ‐Zuschrift über ein schaltbares Donor‐Akzeptor‐Rotaxan . In diesem Jahr wurde ihm bereits der Joel Henry Hildebrand Award der American Chemical Society zuerkannt.…”

Wholly Synthetic Molecular Machines

“…Hence,r edox-responsive units, such as viologens, [71][72][73] tetrathiafulvalene derivatives, [74][75][76] ferrocenes, [77][78][79] naphthalened iimides, [80,81] and so forth, have been incorporated into av ariety of molecular machines. Hence,r edox-responsive units, such as viologens, [71][72][73] tetrathiafulvalene derivatives, [74][75][76] ferrocenes, [77][78][79] naphthalened iimides, [80,81] and so forth, have been incorporated into av ariety of molecular machines.…”

“…As an alternative to developing complicated waste-management circulatory systems, chemists have turned their attention, in the short term at least, to reactions that involvee ither only electron transfers or configurationali somerizationst hat avoid the generation of waste. Hence,r edox-responsive units, such as viologens, [71][72][73] tetrathiafulvalene derivatives, [74][75][76] ferrocenes, [77][78][79] naphthalened iimides, [80,81] and so forth, have been incorporated into av ariety of molecular machines. Cyclobis-(paraquat-p-phenylene)( CBPQT 4 + )f orms interpenetrating trisradicalt riscationic complexes with viologens under reducing conditions [82,83] that dissociate with the aid of strong Coulombic repulsion on subsequento xidation ( Figure 3b).…”