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Article: Dynamic Chirality: Keen selection in the face of stereochemical diversity in mechanically bonded compounds

TitleDynamic Chirality: Keen selection in the face of stereochemical diversity in mechanically bonded compounds
Authors
KeywordsChirality
NMR spectroscopy
Stereochemistry
Structure elucidation
Supramolecular chemistry
Issue Date2003
Citation
Chemistry - A European Journal, 2003, v. 9, n. 2, p. 543-556 How to Cite?
AbstractThe template-directed syntheses, employing bisparaphenylene- [34]crown-10 (BPP34C10), 1,5-dinaphthoparaphenylene-[36] crown-10 (1/5NPPP36C10), and 1,5-dinaphtho-[38]crown-10 (1/5DNP38C10) as templates, of three [2]catenanes, whereby one of the two bipyridinium units in cyclobis(paraquat-p-phenylene) is replaced by a bipicolinium unit, are described. The crude reaction mixtures comprising the [2]catenanes all contain slightly more of the homologous [3]catenanes, wherein a "dimeric" octacationic cyclophane has the crown ether macrocycles encircling the alternating bipyridinium units with the bipicolinium units completely unfettered. X-ray crystallography, performed on all three [2]catenanes and two of the three [3]catenanes reveals co-conformational and stereochemical preferences that are stark and pronounced. Both the [3]catenanes crystallize as mixtures of diastereoisomers on account of the axial chirality associated with the picolinium units in the solid state. Dynamic 1H NMR spectroscopy is employed to probe in solution the relative energy barriers for rotations by the phenylene and pyridinium rings in the tetracationic cyclophane component of the [2]catenanes. Where there are co-conformational changes that are stereochemically "allowed", crown ether circumrotation and rocking processes are also investigated for the relative rates of their occurrence. The outcome is one whereby the three [2]catenanes containing BPP34C10, 1/5NPPP36C10, and 1/5DNP38C10 exist as one major enantiomeric pair of diastereoisomers amongst two, four, and eight diastereoisomeric pairs of enantiomers, respectively. The diastereoisomerism is a consequence of the presence of axial chirality together with helical and/or planar chirality in the same interlocked molecule. These [2]catenanes constitute a rich reserve of new stereochemical types that might be tapped for their switching and mechanical properties.
Persistent Identifierhttp://hdl.handle.net/10722/332530
ISSN
2023 Impact Factor: 3.9
2023 SCImago Journal Rankings: 1.058
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorTseng, Hsian Rong-
dc.contributor.authorVignon, Scott A.-
dc.contributor.authorCelestre, Paul C.-
dc.contributor.authorStoddart, J. Fraser-
dc.contributor.authorWhite, Andrew J.P.-
dc.contributor.authorWilliams, David J.-
dc.date.accessioned2023-10-06T05:12:14Z-
dc.date.available2023-10-06T05:12:14Z-
dc.date.issued2003-
dc.identifier.citationChemistry - A European Journal, 2003, v. 9, n. 2, p. 543-556-
dc.identifier.issn0947-6539-
dc.identifier.urihttp://hdl.handle.net/10722/332530-
dc.description.abstractThe template-directed syntheses, employing bisparaphenylene- [34]crown-10 (BPP34C10), 1,5-dinaphthoparaphenylene-[36] crown-10 (1/5NPPP36C10), and 1,5-dinaphtho-[38]crown-10 (1/5DNP38C10) as templates, of three [2]catenanes, whereby one of the two bipyridinium units in cyclobis(paraquat-p-phenylene) is replaced by a bipicolinium unit, are described. The crude reaction mixtures comprising the [2]catenanes all contain slightly more of the homologous [3]catenanes, wherein a "dimeric" octacationic cyclophane has the crown ether macrocycles encircling the alternating bipyridinium units with the bipicolinium units completely unfettered. X-ray crystallography, performed on all three [2]catenanes and two of the three [3]catenanes reveals co-conformational and stereochemical preferences that are stark and pronounced. Both the [3]catenanes crystallize as mixtures of diastereoisomers on account of the axial chirality associated with the picolinium units in the solid state. Dynamic 1H NMR spectroscopy is employed to probe in solution the relative energy barriers for rotations by the phenylene and pyridinium rings in the tetracationic cyclophane component of the [2]catenanes. Where there are co-conformational changes that are stereochemically "allowed", crown ether circumrotation and rocking processes are also investigated for the relative rates of their occurrence. The outcome is one whereby the three [2]catenanes containing BPP34C10, 1/5NPPP36C10, and 1/5DNP38C10 exist as one major enantiomeric pair of diastereoisomers amongst two, four, and eight diastereoisomeric pairs of enantiomers, respectively. The diastereoisomerism is a consequence of the presence of axial chirality together with helical and/or planar chirality in the same interlocked molecule. These [2]catenanes constitute a rich reserve of new stereochemical types that might be tapped for their switching and mechanical properties.-
dc.languageeng-
dc.relation.ispartofChemistry - A European Journal-
dc.subjectChirality-
dc.subjectNMR spectroscopy-
dc.subjectStereochemistry-
dc.subjectStructure elucidation-
dc.subjectSupramolecular chemistry-
dc.titleDynamic Chirality: Keen selection in the face of stereochemical diversity in mechanically bonded compounds-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1002/chem.200390057-
dc.identifier.pmid12532304-
dc.identifier.scopuseid_2-s2.0-0037455369-
dc.identifier.volume9-
dc.identifier.issue2-
dc.identifier.spage543-
dc.identifier.epage556-
dc.identifier.isiWOS:000180592000020-

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