title: Photoinduced cation translocation in a calix[4]biscrown: towards a new type of light-driven molecular shuttle.
abstract: The photophysics of a ditopic receptor of potassium ion consisting of a 1,3-alternate calix[4]biscrown with a merocyanine dye (DCM) inserted into each crown is reported. Thanks to the large difference between the binding affinity for one and two potassium ions, one can find relative total concentrations of ligand and potassium ion at which the 1:1 complex is most predominant with respect to the free ligand and the 2:1 complex whose amounts are a few percents. Investigation of the 1:1 complex by femtosecond transient absorption spectroscopy provides evidence for the ultrafast movement of a potassium ion through the calix[4]arene tube upon excitation at 400 nm of the dye. Phototranslocation occurs in the picosecond timescale with a non-exponential kinetics without competition with photoejection towards the bulk. The translocation time includes two main short components: 0.83 ps and 10 ps. A smaller-weighted third component of 101 ps might include a competition between phototranslocation and excitation energy transfer as shown by using Förster's theory. These findings open the way to new strategies for light-driven molecular shuttles with the aim of information storage and binary logic computing at a nanometric scale.
authors.affiliation: Département Sciences et Techniques Industrielles, Conservatoire National des Arts et Métiers, 292 rue Saint-Martin, F-75003 Paris, France. bernard.valeur@cnam.fr
authors.forename: Bernard
authors.initials: B
authors.lastname: Valeur
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leray
authors.forename: Liyun
authors.initials: L
authors.lastname: Zhao
authors.forename: Vincent
authors.initials: V
authors.lastname: Souchon
authors.forename: Rémi
authors.initials: R
authors.lastname: Métivier
authors.forename: Pascal
authors.initials: P
authors.lastname: Plaza
authors.forename: Christian
authors.initials: C
authors.lastname: Ley
authors.forename: Fabien
authors.initials: F
authors.lastname: Lacombat
authors.forename: Monique M
authors.initials: MM
authors.lastname: Martin