title: Flexible Viologen Cyclophanes: Odd/Even Effects on Intramolecular Interactions.
abstract: The ability of three bis-viologen cyclophanes to act as redox-triggered contractile switches is investigated. Odd/even effects in the formation of cyclic bis-viologens are circumvented by the use of a Zincke salt intermediate and a tetrathiafulvalene template to prepare a flexible cyclophane with hexyl linkers. Comparative spectro-electrochemical studies of this macrocycle with two other pentyl- or heptyl-linked cyclic bis-viologens show that the development of intramolecular interactions in aqueous solution depends on the length of the bridges. This dependence is confirmed by EPR and DFT studies of the magnetic coupling in the diradical dication species. The anti-ferromagnetic or ferromagnetic nature of the coupling depend, respectively, on the odd or even number of methylene groups in the spacer.
authors.affiliation: Laboratoire de Chimie des Ligands à Architecture Contrôlée, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Berville
authors.affiliation: Laboratoire de Propriétés Optiques et Magnétiques des Architectures Moléculaires, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Choua
authors.affiliation: Laboratoire de Chimie Quantique, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Gourlaouen
authors.affiliation: Laboratoire d'Electrochimie et Chimie Physique du Corps Solide, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Boudon
authors.affiliation: Laboratoire d'Electrochimie et Chimie Physique du Corps Solide, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Laurent
authors.identifier: http://orcid.org/0000-0003-1154-2422
authors.initials: L
authors.lastname: Ruhlmann
authors.affiliation: Service de Cristallographie, GDS 3648, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Bailly
authors.affiliation: Département de Chimie Moléculaire, UMR 5250, Laboratoire de Chimie Inorganique Rédox, Université Grenoble Alpes, 38000, Grenoble, France.
authors.forename: Saioa
authors.identifier: http://orcid.org/0000-0002-9353-3417
authors.initials: S
authors.lastname: Cobo
authors.affiliation: Département de Chimie Moléculaire, UMR 5250, Laboratoire de Chimie Inorganique Rédox, Université Grenoble Alpes, 38000, Grenoble, France.
authors.forename: Eric
authors.identifier: http://orcid.org/0000-0003-0801-5218
authors.initials: E
authors.lastname: Saint-Aman
authors.affiliation: Laboratoire de Chimie des Ligands à Architecture Contrôlée, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Jennifer
authors.identifier: http://orcid.org/0000-0001-5370-4253
authors.initials: J
authors.lastname: Wytko
authors.affiliation: Laboratoire de Chimie des Ligands à Architecture Contrôlée, Institut de Chimie, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008, Strasbourg, France.
authors.forename: Jean
authors.identifier: http://orcid.org/0000-0001-7753-8958
authors.initials: J
authors.lastname: Weiss
keywords: EPR spectroscopy; cyclophanes; electrochemistry; pi-dimer; viologens