Shape-persistent macrocycles comprising perfluorinated benzene subunits : synthesis, aggregation behaviour and unexpected mu-rod formation

Shu, Lijin and Mueri, Marcel and Krupke, Ralph and Mayor, Marcel. (2009) Shape-persistent macrocycles comprising perfluorinated benzene subunits : synthesis, aggregation behaviour and unexpected mu-rod formation. Organic and Biomolecular Chemistry, 7 (6). pp. 1081-1092.

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Official URL: http://edoc.unibas.ch/dok/A5259898

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The synthesis of a series of shape-persistent macrocycles (SPMs) (1-4 and 6) comprising different numbers and/or spatial arrangement of meta-substituted tetrafluorobenzene and benzene subunits interlinked with diacetylenes is described. To increase their solubility, all five SPMs were functionalized by four peripheral hexyl chains. These SPMs were assembled from common diacetylene building blocks by a modular synthetic strategy based on palladium and/or copper catalyzed versions of acetylene coupling reactions (oxidative acetylene coupling and Cadiot-Chodkiewicz coupling). The aggregation properties in chloroform of SPMs 1-6 were investigated by concentration-and temperature-dependent H-1-NMR investigations and by vapour pressure osmometry studies. Aggregation constants and thermodynamic data of the process were obtained by least-squares fitting of the NMR data and by van`t Hoff analysis respectively. Aggregation was only observed for SPMs 2-6 comprising electron deficient tetrafluorobenzene corner units. While dimerization was the major aggregation process for SPMs 3-6, the formation of larger aggregates in solution was only observed for SPM 2. The formation of aggregates is in all cases enthalpically driven. As the largest and the smallest enthalpic contribution and entropic loss in the series of aggregating SPMs were found for the two SPMs 3 and 4, each comprising two fluorinated corner units, the spatial arrangement of these subunits within the macrocycle seems to be at least equally important as the ratio of tetrafluorobenzene and benzene moieties. Interestingly, micro-scaled hexagonal rods were formed from SPM 3 upon heating in toluene, presumably consisting of mixtures of oligomers arising from covalently interlinked macrocycles.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Molecular Devices and Materials (Mayor)
UniBasel Contributors:Mayor, Marcel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:05 Apr 2017 14:13
Deposited On:22 Mar 2012 14:07

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