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Tabatchnik-Rebillon, A., Aube, C., Bakkali, H., Delaunay, T., Manh, G. T., Blot, V., Thobie-Gautier, C., Renault, E., Soulard, M., Planchat, A., Le Questel, J.-Y., Le Guevel, R., Guguen-Guillouzo, C., Kauffmann, B., Ferrand, Y., Huc, I., Urgin, K., Condon, S., Leonel, E., Evain, M., Lebreton, J., Jacquemin, D., Pipelier, M. & Dubreuil, D. (2010) Electrochemical Synthesis and Characterisation of Alternating Tripyridyl-Dipyrrole Molecular Strands with Multiple Nitrogen-Based Donor-Acceptor Binding Sites. Chem.-Eur. J. 16 11876–11889.
Added by: Laurent Cournède (2016-03-10 21:37:33) |
| Type de référence: Article DOI: 10.1002/chem.201000859 Numéro d'identification (ISBN etc.): 0947-6539 Clé BibTeX: TabatchnikRebillon2010 Voir tous les détails bibliographiques  |
Catégories: MIOPS Mots-clés: 2-(2'-pyridyl)pyrroles, Band-gap, complexes, copolymers, Copper, electrochemistry, heterocycles, N ligands, Nitrogen heterocycles, polymers, precursors, pyrrole, reduction, ring contraction, systems Créateurs: Aube, Bakkali, Blot, Condon, Delaunay, Dubreuil, Evain, Ferrand, Guguen-Guillouzo, Huc, Jacquemin, Kauffmann, Le Guevel, Le Questel, Lebreton, Leonel, Manh, Pipelier, Planchat, Renault, Soulard, Tabatchnik-Rebillon, Thobie-Gautier, Urgin Collection: Chem.-Eur. J. |
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| Résumé |
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Synthesis of alternating pyridine-pyrrole molecular strands composed of two electron-rich pyrrole units (donors) sandwiched between three pyridinic cores (acceptors) is described. The envisioned strategy was a smooth electrosynthesis process involving ring contraction of corresponding tripyridyl-dipyridazine precursors. 2,6-Bis[6-(pyridazin-3-yl)]pyridine ligands 2a-c bearing pyridine residues at the terminal positions were prepared in suitable quantities by a Negishi metal cross-coupling procedure. The yields of heterocyclic coupling between 2-pyridyl zinc bromide reagents 12a-c and 2,6-bis(6-trifluoromethanesulfonylpyridazin-3-yl)pyridine increased from 68 to 95\% following introduction of electron-donating methyl groups on the metallated halogenopyridine units. Favorable conditions for preparative electrochemical reduction of tripyridyl-dipyridazines 2b,c were established in THF/acetate buffer (pH 4.6)/acetonitrile to give the targeted 2,6-bis[5-(pyridin-2-yl)pyrrol-2-yl]pyridines 1b and 1c in good yields. The absorption behavior of the donor-acceptor tripyridyl-dipyrrole ligands was evaluated and compared to theoretical calculations. Highly fluorescent properties of these chromophores were found (v(cm)approximate to 2 x 10(4) cm(-1) in MeOH and CH(2)Cl(2)), and both pyrrolic ligands exhibit a remarkable quantum yield in CH(2)Cl(2) (phi(f)=0.10). Structural studies in the solid state established the preferred cis conformation of the dipyrrolic ligands, which adopting a planar arrangement with an embedded molecule of water having a complexation energy exceeding 10 kcal mol(-1). The ability of the tripyridyl-dipyrrole to complex two copper(II) ions in a pentacoordinate square was investigated.
Added by: Laurent Cournède |