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Artificial Molecular Machines.

Erbas-Cakmak S, Leigh DA, McTernan CT, Nussbaumer AL - Chem. Rev. (2015)

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.

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bonded molecules and on catenanes and rotaxanes in which switching of other protic solvents... This effect (listed in descending binding ability) stations on the thread, macrocycle In these systems, fast-responding reporters are preferred... practical applications by utilizing molecular scale changes to create macroscopic effects... The thread of these rotaxanes included an anthracene fluorophore similar application in synthetic polymers often furnishes a useful result... of Brownian motion can be exploited to great effect in the synthesis every aspect of functional molecule and materials design... An improved robotics” in which ratcheted motions of molecular components

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Initially the system is balanced (in proportion to thesizes ofthe two compartments), with an equal density of particles in the leftand the right compartments. By changing the volume of the left-handcompartment, the system becomes statistically unbalanced. Openingthe door allows the particle to redistribute according to the newsize of the compartments. Closing the door ratchets the new distributionof the particles. Restoring the left compartment to its original sizeresults in a concentration gradient of the Brownian particles acrossthe two compartments. Here, the size of the compartment representsthe energy level of the macrocycle-station system.75
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fig29: Initially the system is balanced (in proportion to thesizes ofthe two compartments), with an equal density of particles in the leftand the right compartments. By changing the volume of the left-handcompartment, the system becomes statistically unbalanced. Openingthe door allows the particle to redistribute according to the newsize of the compartments. Closing the door ratchets the new distributionof the particles. Restoring the left compartment to its original sizeresults in a concentration gradient of the Brownian particles acrossthe two compartments. Here, the size of the compartment representsthe energy level of the macrocycle-station system.75

Mentions: In this system, the exchange of the macrocycle between stationscould be controlled by the introduction of a barrier in the middleof the thread (kinetic control) as well as by altering the bindingaffinity of the macrocycle to the two different stations (thermodynamiccontrol). Initially, 85% of the macrocycle bound the fumaramide stationand 15% the succinamide station. The system was still unlinked becauseof the kinetic barrier and therefore not in equilibrium. A balance-breakingstimulus (photoisomerization at 312 nm) generated a 49:51 E:Z photostationary state. Removal of the barrier, the linkingstimulus, allowed the balance to be restored by the macrocycle equilibration.Restoring the barrier unlinked the system. The last step was Z → E olefin isomerization, whichmade the system statistically unbalanced, unlinked, and not in equilibrium.After one operational cycle of the machine, 56% of the macrocycleswere located on the succinamide station. The thread had thereforechanged the net position of the macrocycle. Because the succinamidestation binds the macrocycle less strongly than the fumaramide station,this process has moved the macrocycle energetically uphill; that is,it has performed a ratcheting operation, transporting a particle awayfrom equilibrium. This system and its function is an experimentalrealization of the transportation task required in Smoluchowski’strapdoor and Maxwell’s pressure demon, which are discussedin the introduction (section 1) and are powered by chemical and light energy. Figure 29 shows a schematicrepresentation of the four sequential steps performed by rotaxane 75 to transport the system energetically uphill: balance-breaking1, linking, unlinking, balance breaking 2 (resetting the machine butnot the substrate).


Artificial Molecular Machines.

Erbas-Cakmak S, Leigh DA, McTernan CT, Nussbaumer AL - Chem. Rev. (2015)

Initially the system is balanced (in proportion to thesizes ofthe two compartments), with an equal density of particles in the leftand the right compartments. By changing the volume of the left-handcompartment, the system becomes statistically unbalanced. Openingthe door allows the particle to redistribute according to the newsize of the compartments. Closing the door ratchets the new distributionof the particles. Restoring the left compartment to its original sizeresults in a concentration gradient of the Brownian particles acrossthe two compartments. Here, the size of the compartment representsthe energy level of the macrocycle-station system.75
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4585175&req=5

fig29: Initially the system is balanced (in proportion to thesizes ofthe two compartments), with an equal density of particles in the leftand the right compartments. By changing the volume of the left-handcompartment, the system becomes statistically unbalanced. Openingthe door allows the particle to redistribute according to the newsize of the compartments. Closing the door ratchets the new distributionof the particles. Restoring the left compartment to its original sizeresults in a concentration gradient of the Brownian particles acrossthe two compartments. Here, the size of the compartment representsthe energy level of the macrocycle-station system.75
Mentions: In this system, the exchange of the macrocycle between stationscould be controlled by the introduction of a barrier in the middleof the thread (kinetic control) as well as by altering the bindingaffinity of the macrocycle to the two different stations (thermodynamiccontrol). Initially, 85% of the macrocycle bound the fumaramide stationand 15% the succinamide station. The system was still unlinked becauseof the kinetic barrier and therefore not in equilibrium. A balance-breakingstimulus (photoisomerization at 312 nm) generated a 49:51 E:Z photostationary state. Removal of the barrier, the linkingstimulus, allowed the balance to be restored by the macrocycle equilibration.Restoring the barrier unlinked the system. The last step was Z → E olefin isomerization, whichmade the system statistically unbalanced, unlinked, and not in equilibrium.After one operational cycle of the machine, 56% of the macrocycleswere located on the succinamide station. The thread had thereforechanged the net position of the macrocycle. Because the succinamidestation binds the macrocycle less strongly than the fumaramide station,this process has moved the macrocycle energetically uphill; that is,it has performed a ratcheting operation, transporting a particle awayfrom equilibrium. This system and its function is an experimentalrealization of the transportation task required in Smoluchowski’strapdoor and Maxwell’s pressure demon, which are discussedin the introduction (section 1) and are powered by chemical and light energy. Figure 29 shows a schematicrepresentation of the four sequential steps performed by rotaxane 75 to transport the system energetically uphill: balance-breaking1, linking, unlinking, balance breaking 2 (resetting the machine butnot the substrate).

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

bonded molecules and on catenanes and rotaxanes in which switching of other protic solvents... This effect (listed in descending binding ability) stations on the thread, macrocycle In these systems, fast-responding reporters are preferred... practical applications by utilizing molecular scale changes to create macroscopic effects... The thread of these rotaxanes included an anthracene fluorophore similar application in synthetic polymers often furnishes a useful result... of Brownian motion can be exploited to great effect in the synthesis every aspect of functional molecule and materials design... An improved robotics” in which ratcheted motions of molecular components

No MeSH data available.


Related in: MedlinePlus