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Article: The mechanism of the slippage approach to rotaxanes. Origin of the 'all- or-nothing' substituent effect
Title | The mechanism of the slippage approach to rotaxanes. Origin of the 'all- or-nothing' substituent effect |
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Authors | |
Issue Date | 1998 |
Citation | Journal of the American Chemical Society, 1998, v. 120, n. 36, p. 9318-9322 How to Cite? |
Abstract | Heating a solution of the circular bis-p-phenylene-34-crown-10 and a dumbbell-shaped bipyridinium component, terminated at both ends by 4-R- phenyl-bis(4-tert-butyl-phenyl)methane-based stoppers, affords the corresponding [2]rotaxane when R is equal to H, Me, and Et, following the slippage of the macrocycle over the stoppers of the dumbbell. By contrast, no [2]rotaxane is obtained when R is equal to i-Pr. Computational investigations with the AMBER* force field provide an explanation of this dramatic substitutent effect. The phenomenon was simulated by the passage of the bis- p-phenylene-34-crown-10 macrocycle over four 4-R-phenyl-bis(4-tert-butyl- phenyl)methane model stoppers. For R equal to H, Me, Et, and i-Pr, there are two main energy barriers which have to be surpassed in order to permit the passage of the macrocycle over the bulky stoppers. When R is equal to H or Me, the rate-determining step is the passage of the macrocycle over a t-Bu- C6H4- ring. By contrast, when R is equal to Et or i-Pr, the rate- determining step becomes the passage of the macrocycle over the R-C6H4- ring. However, when R is equal to i-Pr, the resulting energy barrier is more than 21 kcal mol-1 higher than in the case of any of the other stoppers. These results are in good agreement with the experimental observations and provide a quantitative explanation for the rigorous size complementarily requirements between macrocycle and stopper which have been observed experimentally. |
Persistent Identifier | http://hdl.handle.net/10722/333658 |
ISSN | 2023 Impact Factor: 14.4 2023 SCImago Journal Rankings: 5.489 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Raymo, Françisco M. | - |
dc.contributor.author | Houk, K. N. | - |
dc.contributor.author | Stoddart, J. Fraser | - |
dc.date.accessioned | 2023-10-06T05:21:22Z | - |
dc.date.available | 2023-10-06T05:21:22Z | - |
dc.date.issued | 1998 | - |
dc.identifier.citation | Journal of the American Chemical Society, 1998, v. 120, n. 36, p. 9318-9322 | - |
dc.identifier.issn | 0002-7863 | - |
dc.identifier.uri | http://hdl.handle.net/10722/333658 | - |
dc.description.abstract | Heating a solution of the circular bis-p-phenylene-34-crown-10 and a dumbbell-shaped bipyridinium component, terminated at both ends by 4-R- phenyl-bis(4-tert-butyl-phenyl)methane-based stoppers, affords the corresponding [2]rotaxane when R is equal to H, Me, and Et, following the slippage of the macrocycle over the stoppers of the dumbbell. By contrast, no [2]rotaxane is obtained when R is equal to i-Pr. Computational investigations with the AMBER* force field provide an explanation of this dramatic substitutent effect. The phenomenon was simulated by the passage of the bis- p-phenylene-34-crown-10 macrocycle over four 4-R-phenyl-bis(4-tert-butyl- phenyl)methane model stoppers. For R equal to H, Me, Et, and i-Pr, there are two main energy barriers which have to be surpassed in order to permit the passage of the macrocycle over the bulky stoppers. When R is equal to H or Me, the rate-determining step is the passage of the macrocycle over a t-Bu- C6H4- ring. By contrast, when R is equal to Et or i-Pr, the rate- determining step becomes the passage of the macrocycle over the R-C6H4- ring. However, when R is equal to i-Pr, the resulting energy barrier is more than 21 kcal mol-1 higher than in the case of any of the other stoppers. These results are in good agreement with the experimental observations and provide a quantitative explanation for the rigorous size complementarily requirements between macrocycle and stopper which have been observed experimentally. | - |
dc.language | eng | - |
dc.relation.ispartof | Journal of the American Chemical Society | - |
dc.title | The mechanism of the slippage approach to rotaxanes. Origin of the 'all- or-nothing' substituent effect | - |
dc.type | Article | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1021/ja9806229 | - |
dc.identifier.scopus | eid_2-s2.0-0032538060 | - |
dc.identifier.volume | 120 | - |
dc.identifier.issue | 36 | - |
dc.identifier.spage | 9318 | - |
dc.identifier.epage | 9322 | - |
dc.identifier.isi | WOS:000075954000023 | - |