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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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Schematic representation and molecular structureof a bifunctionalorganocatalyst integrated in a directional light-driven molecularmotor. A, DMAP; B, thiourea hydrogen-bonding donor group. (a) A andB are remote. (b) A and B are in close proximity with M helicity in the (M,M)-cis-140 isomer, preferentially providing the(S) enantiomer of the reaction product. (c) A andB are in close proximity with P helicity in the (P,P)-cis-140 isomer, generating (R) enriched product. Step 1:irradiation at 312 nm at 20 °C. Step 2: heating at 70 °C.Step 3: irradiation at 312 nm at −60 °C. Step 4: temperature−10 °C.1424
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fig54: Schematic representation and molecular structureof a bifunctionalorganocatalyst integrated in a directional light-driven molecularmotor. A, DMAP; B, thiourea hydrogen-bonding donor group. (a) A andB are remote. (b) A and B are in close proximity with M helicity in the (M,M)-cis-140 isomer, preferentially providing the(S) enantiomer of the reaction product. (c) A andB are in close proximity with P helicity in the (P,P)-cis-140 isomer, generating (R) enriched product. Step 1:irradiation at 312 nm at 20 °C. Step 2: heating at 70 °C.Step 3: irradiation at 312 nm at −60 °C. Step 4: temperature−10 °C.1424

Mentions: Feringa et al. used one oftheir rotary molecular motors basedon a chiral overcrowded alkene, which can perform a directional 360°rotary cycle fueled by light and heat to create a photoswitchablecatalyst. During this rotation, the helicity of the motor changes,which changes the overall chirality of the system. A DMAP (dimethylaminopyridine)Brønsted base (Figure 54) and a thiourea hydrogen-bonding donor group, which togethercomprise a bifunctional organocatalyst, perform Michael additionswhen in close proximity. As a consequence, the catalytic activityas well the stereoselectivity can be controlled. Michael additionof 2-methoxy thiophenol to cyclohexanone was used as a test system.The (P,P)-trans-140 isomer resulted in a racemic (R,S)-thiol adduct in low yield (7%) after a lengthyreaction. When the (M,M)-cis-140 isomer was used, the Michael additionproceeded significantly faster furnishing a 50% yield of product,with an er of 75/25 (S/R). Finally,the (P,P)-cis-140 isomer led an 83% yield with an inversion in enantioselectivityproviding an er of 23/77 (S/R).1424 Recently, the same group reported a bisphosphinederivative of the same photoswitchable rotary motor. Both productenantiomers of a palladium-catalyzed desymmetrization reaction couldbe formed, although in situ switching experiments were complicatedby the photosensitivity of the active palladium complex.1425


Artificial Molecular Machines.

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

Schematic representation and molecular structureof a bifunctionalorganocatalyst integrated in a directional light-driven molecularmotor. A, DMAP; B, thiourea hydrogen-bonding donor group. (a) A andB are remote. (b) A and B are in close proximity with M helicity in the (M,M)-cis-140 isomer, preferentially providing the(S) enantiomer of the reaction product. (c) A andB are in close proximity with P helicity in the (P,P)-cis-140 isomer, generating (R) enriched product. Step 1:irradiation at 312 nm at 20 °C. Step 2: heating at 70 °C.Step 3: irradiation at 312 nm at −60 °C. Step 4: temperature−10 °C.1424
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4585175&req=5

fig54: Schematic representation and molecular structureof a bifunctionalorganocatalyst integrated in a directional light-driven molecularmotor. A, DMAP; B, thiourea hydrogen-bonding donor group. (a) A andB are remote. (b) A and B are in close proximity with M helicity in the (M,M)-cis-140 isomer, preferentially providing the(S) enantiomer of the reaction product. (c) A andB are in close proximity with P helicity in the (P,P)-cis-140 isomer, generating (R) enriched product. Step 1:irradiation at 312 nm at 20 °C. Step 2: heating at 70 °C.Step 3: irradiation at 312 nm at −60 °C. Step 4: temperature−10 °C.1424
Mentions: Feringa et al. used one oftheir rotary molecular motors basedon a chiral overcrowded alkene, which can perform a directional 360°rotary cycle fueled by light and heat to create a photoswitchablecatalyst. During this rotation, the helicity of the motor changes,which changes the overall chirality of the system. A DMAP (dimethylaminopyridine)Brønsted base (Figure 54) and a thiourea hydrogen-bonding donor group, which togethercomprise a bifunctional organocatalyst, perform Michael additionswhen in close proximity. As a consequence, the catalytic activityas well the stereoselectivity can be controlled. Michael additionof 2-methoxy thiophenol to cyclohexanone was used as a test system.The (P,P)-trans-140 isomer resulted in a racemic (R,S)-thiol adduct in low yield (7%) after a lengthyreaction. When the (M,M)-cis-140 isomer was used, the Michael additionproceeded significantly faster furnishing a 50% yield of product,with an er of 75/25 (S/R). Finally,the (P,P)-cis-140 isomer led an 83% yield with an inversion in enantioselectivityproviding an er of 23/77 (S/R).1424 Recently, the same group reported a bisphosphinederivative of the same photoswitchable rotary motor. Both productenantiomers of a palladium-catalyzed desymmetrization reaction couldbe formed, although in situ switching experiments were complicatedby the photosensitivity of the active palladium complex.1425

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.