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Tetrathiafulvalene Crowns: Redox-Switchable Ligands

A series of redox‐responsive ligands that associate the electroactive tetrathiafulvalene core with polyether subunits of various lengths has been synthesized. X‐ray structures are provided for each of the free ligands. The requisite structural criteria for reaching switchable ligands are satisfied f...

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Bibliographic Details
Published in:Chemistry : a European journal 2001-01, Vol.7 (2), p.447-455
Main Authors: Le Derf, Franck, Mazari, Miloud, Mercier, Nicolas, Levillain, Eric, Trippé, Gaëlle, Riou, Amédée, Richomme, Pascal, Becher, Jan, Garín, Javier, Orduna, Jesus, Gallego-Planas, Nuria, Gorgues, Alain, Sallé, Marc
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Language:English
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Summary:A series of redox‐responsive ligands that associate the electroactive tetrathiafulvalene core with polyether subunits of various lengths has been synthesized. X‐ray structures are provided for each of the free ligands. The requisite structural criteria for reaching switchable ligands are satisfied for the largest macrocycles, that is, planarity of the 1,1′,3,3′‐tetrathiafulvalene (TTF) π system and correctly oriented coordinating atoms. The ability of these ligands to recognize various metal cations as a function of the cavity size has been investigated by various techniques (LSIMS, 1H NMR, and UV/Vis spectroscopy, cyclic voltammetry). These systems exhibit an unprecedented high coordination ability among TTF crown ethers. Their switchable ligating properties have been confirmed by cyclic voltammetry, and metal‐cation complexation has been illustrated by X‐ray structures of three of the corresponding metal complexes (Pb2+, Sr2+, and Ba2+). Solid‐state structures of these complexes display original packing modes with channel‐like arrangements. Une famille de ligands électrochimiquement contrôlés, associant le cœur électroactif tétrathiafulvalène aux unités polyéthers complexantes de différentes longueurs, a été synthétisée. Les structures RX de chacun des ligands libres ont été résolues et répondent, pour les plus grands d'entre‐eux, aux critères requis pour la modulation redox de la constante de complexation: planéité du système‐π et atomes coordonnants correctement orientés vers le centre de la cavité. Leur aptitude à reconnaître des cations métalliques variés en fonction de la taille de la cavité a été étudiée par différentes techniques (LSIMS, RMN 1H, UV/Vis, voltampérométrie cyclique); ces systèmes disposent de propriétés complexantes supérieures à celles des ligands TTF‐couronnes déjà décrits. Leur aptitude à moduler la complexation a été confirmée par voltampérométrie cyclique et enfin, la coordination de cations métalliques est illustrée par les structures à l'état solide de trois complexes correspondants (Pb2+, Sr2+ and Ba2+). Les structures de ces complexes montrent des modes d'empilements originaux sous la forme de canaux. Electrochemical control of the complexation/expulsion switchable process is facilitated by crown‐TTF ligands with different cavity sizes, such as the one shown here, that display high coordination abilities for various metal cations.
ISSN:0947-6539
1521-3765
DOI:10.1002/1521-3765(20010119)7:2<447::AID-CHEM447>3.0.CO;2-A