Self-assembly of Ag(I) helicates with new enantiopure 5,6-Chiragen type ligands

Mamula Steiner, Olimpia (School of Engineering and Architecture (HEIA-FR), HES-SO // University of Applied Sciences Western Switzerland ; Chemistry Department, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland) ; Bark, Thomas (Chemistry Department, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland) ; Quinodoz, Boris (Chemistry Department, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland) ; Stoeckli-Evans, Helen (Institute of Physics, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland) ; Zelewsky, Alex von (Chemistry Department, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland)

Two new chiral bis-bidentate, C2-symmetrical ligands belonging to the Chiragen family have been synthesised and characterised. They are designed for polynuclear self-assemblies since the two (-)-5,6- pinenebipyridines units are connected by bridges whose length and rigidity avoids the coordination of the bipyridine moieties to the same metal centre. The ligand L1 with a 1,4-dimethylene naphthalene bridge leads, by complexation with Ag(I) cations, to a polymeric, single stranded helix. The helical pitch contains five metal centers, two consecutive metal centers being connected by a bis-bidentate, helically wrapped ligand, one up and the other down resulting in a coordination number four. The chirality (K) around each metal centre is controlled by the six asymmetric carbons of the ligands and the homochirality of the metal centers gives rise to a P orientation at the helix level. The 1 H-NMR measurements of these species in solution indicate a temperature dependent behaviour pointing out possible equilibria between various [AgnLn] n+ fragments as confirmed by MS-spectroscopy. The ligand L2 with a 4,40 -dimethylene1,10 -biphenyl bridge reacts with Ag(I) and lead to well resolved and temperature independent 1 H-NMR spectra suggesting the formation of a circular helicate.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEIA-FR
Institute:
ChemTech - Institut des technologies chimiques
Subject(s):
Ingénierie
Date:
2018-04
Pagination:
7 p.
Published in:
Inorganica Chimia Acta
Numeration (vol. no.):
2018, 475, pp. 200-206
DOI:
ISSN:
0020-1693
Appears in Collection:



 Record created 2018-09-11, last modified 2018-12-20

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