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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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(a) The chemical structure of the model walker 127,and (b) gradual change in 1H NMR of the model walkerin d6-DMSO upon formation of new positionalisomer on the track. Ratio of (1):(2) isomers reaches 1:0.9 after15 h of operation. (c) Chemical structure of the walker on a largertrack bearing an anthracene moiety, 128. (d) Fluorescencequenching of anthracene after 6.5 h of walking. Reprinted with permissionfrom ref (1397). Copyright2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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fig50: (a) The chemical structure of the model walker 127,and (b) gradual change in 1H NMR of the model walkerin d6-DMSO upon formation of new positionalisomer on the track. Ratio of (1):(2) isomers reaches 1:0.9 after15 h of operation. (c) Chemical structure of the walker on a largertrack bearing an anthracene moiety, 128. (d) Fluorescencequenching of anthracene after 6.5 h of walking. Reprinted with permissionfrom ref (1397). Copyright2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mentions: Leigh et al. reported a spontaneous walking process usinga Michaeladdition reaction between an α-methylene-4-nitrostyrene walkerand a polyamine track (Figure 50).1397 It was shown thatthe walker translocated preferentially through successive 1,4-N,N-migration rather than by overstepping.After 48 h, no out of sequence N,N-migration was observed with a model walker (Figure 50a,b). 1H NMR analysis showedthat the walking was highly solvent dependent and accelerated in polarsolvents such as dimethylformamide and dimethyl sulfoxide. In d6-DMSO, the walker reached an equilibrium distributionin 15 h. A ratio of 1:0.9 between the occupancy of initial positionand the central amine of the track was achieved over this time period.Intermolecular exchange of less than 6% took place when the modelwalker was mixed with a longer free track for 3 days. This indicatesa high processivity (on average 530 steps taken before detachment).Using a longer track modified with an anthracene at the far end, itwas possible to monitor walking via an observed decrease in fluorescenceas the walker approached the anthracene. As the nitrostyrene walkerapproached the edge of the track, it quenched the fluorophore (Figure 50d). Leigh et al.have since reported an extended system with a naphthalene moiety atone end of the track (Figure 51 a).1398 In the presence of excessbase (iPr2NEt), the walker was “trapped”by the naphthylmethylamine, which was the thermodynamic sink. 1H NMR analysis showed that the steady-state distribution ofthe walker was biased and 46% of walker molecules had reached thefinal benzylic foothold in 48 h (Figure 51b,c). When a longer track (with 9 footholds)was used, the percentage at the final station dropped to 19%.


Artificial Molecular Machines.

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

(a) The chemical structure of the model walker 127,and (b) gradual change in 1H NMR of the model walkerin d6-DMSO upon formation of new positionalisomer on the track. Ratio of (1):(2) isomers reaches 1:0.9 after15 h of operation. (c) Chemical structure of the walker on a largertrack bearing an anthracene moiety, 128. (d) Fluorescencequenching of anthracene after 6.5 h of walking. Reprinted with permissionfrom ref (1397). Copyright2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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fig50: (a) The chemical structure of the model walker 127,and (b) gradual change in 1H NMR of the model walkerin d6-DMSO upon formation of new positionalisomer on the track. Ratio of (1):(2) isomers reaches 1:0.9 after15 h of operation. (c) Chemical structure of the walker on a largertrack bearing an anthracene moiety, 128. (d) Fluorescencequenching of anthracene after 6.5 h of walking. Reprinted with permissionfrom ref (1397). Copyright2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mentions: Leigh et al. reported a spontaneous walking process usinga Michaeladdition reaction between an α-methylene-4-nitrostyrene walkerand a polyamine track (Figure 50).1397 It was shown thatthe walker translocated preferentially through successive 1,4-N,N-migration rather than by overstepping.After 48 h, no out of sequence N,N-migration was observed with a model walker (Figure 50a,b). 1H NMR analysis showedthat the walking was highly solvent dependent and accelerated in polarsolvents such as dimethylformamide and dimethyl sulfoxide. In d6-DMSO, the walker reached an equilibrium distributionin 15 h. A ratio of 1:0.9 between the occupancy of initial positionand the central amine of the track was achieved over this time period.Intermolecular exchange of less than 6% took place when the modelwalker was mixed with a longer free track for 3 days. This indicatesa high processivity (on average 530 steps taken before detachment).Using a longer track modified with an anthracene at the far end, itwas possible to monitor walking via an observed decrease in fluorescenceas the walker approached the anthracene. As the nitrostyrene walkerapproached the edge of the track, it quenched the fluorophore (Figure 50d). Leigh et al.have since reported an extended system with a naphthalene moiety atone end of the track (Figure 51 a).1398 In the presence of excessbase (iPr2NEt), the walker was “trapped”by the naphthylmethylamine, which was the thermodynamic sink. 1H NMR analysis showed that the steady-state distribution ofthe walker was biased and 46% of walker molecules had reached thefinal benzylic foothold in 48 h (Figure 51b,c). When a longer track (with 9 footholds)was used, the percentage at the final station dropped to 19%.

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