Defining Unidirectional Motions and Structural Reconfiguration in a Macrocyclic Molecular Motor

Regen-Pregizer, Benjamin Lukas; Dube, Henry

doi:10.1021/jacs.3c01567

Cited by 13 publications

(7 citation statements)

References 47 publications

(66 reference statements)

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“…The interconnection of the stator and the rotor of the motor by two polymer chains generated a twisted state upon rotation, which triggered the reverse rotation as observed by Giuseppone and co‐workers [37] . Dube and colleagues utilised the connection between the stator and the rotor to transmit the molecular rotation onto other entities of the macrocycle [38a,c–d] or allow active molecular threading [38b] …”

Section: Photoswitchable Frameworkmentioning

confidence: 97%

Photoresponsive Supramolecular Cages and Macrocycles

Nieland,

Voss,

Schmidt

2023

ChemPlusChem

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The utilisation of light to achieve precise manipulation and control over the structure and function of supramolecular assemblies has emerged as a highly promising approach in the development of complex, configurable, or multifunctional systems and nanoscopic machine‐like entities. In this minireview, we highlight recent examples of self‐assembled and covalently bound cages and macrocycles with a focus on the external and internal functionalisation of a structure with a photoswitchable unit or the embedment of a photoswitch into the framework of a structure. Functionalising the interior or exterior of a supramolecular cage or macrocycle with a photoresponsive group enables control over different properties, such as guest binding or assembly in the solid‐state, while the overall shape of the assembly often undergoes no significant change. By directly integrating a photoswitchable unit into the framework of a supramolecular structure, the isomerisation can either induce a geometry change, the disassembly, or the disassembly and reassembly of the structure. Historical and recent examples covered in this review are based on azobenzene, diarylethene, stilbene photoswitches, or alkene motors that were incorporated into macrocycles and cages constructed by metal‐organic, dynamic covalent, or covalent bonds.

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Section: Photoswitchable Frameworkmentioning

confidence: 97%

Photoresponsive Supramolecular Cages and Macrocycles

Nieland,

Voss,

Schmidt

2023

ChemPlusChem

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“… A series of light‐driven rotary motors based on ( A ) an overcrowded alkene, [41a,b] ( B ) an imine, [41c] ( C ) a hemithioindigo moiety [41d,e,h] and ( D ) an oxindole [41f,g] . The motors operate through similar cycles ( A ).…”

Section: Light‐driven Ratchetsmentioning

confidence: 99%

“…Other molecular designs have been produced based on a hemithioindigo moiety (Figure 33C) [41d,e,h] and oxindoles (Figure 33D). [41f,g] Like the first‐generation overcrowded alkene motors, the hemithioindigo and oxindole motors lack C 2 ‐symmetry about the alkene bond.…”

Section: Light‐driven Ratchetsmentioning

confidence: 99%

Molecular Ratchets and Kinetic Asymmetry: Giving Chemistry Direction

Borsley,

Leigh,

Roberts

2024

Angewandte Chemie

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In recent years ratchet mechanisms have transformed the understanding and design of stochastic molecular systems—biological, chemical and physical—in a move away from the mechanical macroscopic analogies that dominated thinking regarding molecular dynamics in the 1990s and early 2000s (e.g. pistons, springs, etc), to the more scale‐relevant concepts that underpin out‐of‐equilibrium research in the molecular sciences today. Ratcheting has established molecular nanotechnology as a research frontier for energy transduction and metabolism, and has enabled the reverse engineering of biomolecular machinery, delivering insights into how molecules ‘walk’ and track‐based synthesizers operate, how the acceleration of chemical reactions enables energy to be transduced by catalysts, and how dynamic (supra)molecular systems can be driven away from equilibrium. The recognition of molecular ratchet mechanisms in biology, and their invention in synthetic systems, is proving significant in areas as diverse as supramolecular chemistry, systems chemistry, dynamic covalent chemistry, DNA nanotechnology, polymer and materials science, molecular biology, heterogeneous catalysis, endergonic synthesis, and many other branches of chemical science. Put simply, ratchet mechanisms give chemistry direction. Kinetic asymmetry, quantified by the outcome of ratcheting, is the dynamic counterpart of structural asymmetry (i.e. chirality). Given the ubiquity of ratchet mechanisms, it is surely just as fundamentally important.

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“…Artificial molecular motors have been developed that transduce energy from various sources (including chemical reagents, , light, and electricity) into directionally biased dynamics. The earliest synthetic chemically driven motor molecules required up to 8-step reaction sequences for their operation. , Simpler “pulsed fuel” systems , (one fuel pulse required for each cycle of the motor) were subsequently developed, and the first autonomous artificial chemically fueled motor molecules based, like biomolecular motors, on the motor’s catalysis ,,− , of fuel-to-waste reactions have recently been realized .…”

Section: Introductionmentioning

confidence: 99%

Stepwise Operation of a Molecular Rotary Motor Driven by an Appel Reaction

Zwick,

Troncossi,

Borsley

et al. 2024

J. Am. Chem. Soc.

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To date, only a small number of chemistries and chemical fueling strategies have been successfully used to operate artificial molecular motors. Here, we report the 360°directionally biased rotation of phenyl groups about a C−C bond, driven by a stepwise Appel reaction sequence. The motor molecule consists of a biaryl-embedded phosphine oxide and phenol, in which full rotation around the biaryl bond is blocked by the P−O oxygen atom on the rotor being too bulky to pass the oxygen atom on the stator. Treatment with SOCl 2 forms a cyclic oxyphosphonium salt (removing the oxygen atom of the phosphine oxide), temporarily linking the rotor with the stator. Conformational exchange via ring flipping then allows the rotor and stator to twist back and forth past the previous limit of rotation. Subsequently, the ring opening of the tethered intermediate with a chiral alcohol occurs preferentially through a nucleophilic attack on one face. Thus, the original phosphine oxide is reformed with net directional rotation about the biaryl bond over the course of the two-step reaction sequence. Each repetition of SOCl 2 −chiral alcohol additions generates another directionally biased rotation. Using the same reaction sequence on a derivative of the motor molecule that forms atropisomers rather than fully rotating 360°results in enantioenrichment, suggesting that, on average, the motor molecule rotates in the "wrong" direction once every three fueling cycles. The interconversion of phosphine oxides and cyclic oxyphosphonium groups to form temporary tethers that enable a rotational barrier to be overcome directionally adds to the strategies available for generating chemically fueled kinetic asymmetry in molecular systems.

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Defining Unidirectional Motions and Structural Reconfiguration in a Macrocyclic Molecular Motor

Cited by 13 publications

References 47 publications

Photoresponsive Supramolecular Cages and Macrocycles

Photoresponsive Supramolecular Cages and Macrocycles

Molecular Ratchets and Kinetic Asymmetry: Giving Chemistry Direction

Stepwise Operation of a Molecular Rotary Motor Driven by an Appel Reaction

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