title: Functionalized Triptycene-Derived Tripodal Ligands: Privileged Formation of Tetranuclear Cage Assemblies with Larger Ln(III).
abstract: In this Article, we report the self-assembly of lanthanide complexes formed with two new tripodal ligands, L2 and L3, where binding strands are connected to a rigid triptycene anchor. The pyridine moieties are functionalized with methoxy and PEG groups to enhance ligand solubility and to evaluate the effect of these substituents on lanthanide coordination. These ligands were successfully synthesized and characterized, and their coordination properties were examined along the lanthanide series through speciation studies with NMR and ESI-MS. Well-defined tetranuclear complexes are formed with both ligands, but their stabilities with heavier lanthanides are considerably reduced, especially for complexes with L3. This is attributed to a destabilizing effect of pending PEG arms in combination with increased steric hindrance between binding strands upon complexation with smaller cations. The sensitization of lanthanide luminescence in tetranuclear complexes occurs despite one water molecule being coordinated to a metal ion.
authors.affiliation: CBM-CNRS Orléans , Rue Charles Sadron, 45071 Orléans Cedex 2, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Vuillamy
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Geneva , 30 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Soumaila
authors.initials: S
authors.lastname: Zebret
authors.affiliation: Laboratory of Crystallography, University of Geneva , 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Céline
authors.initials: C
authors.lastname: Besnard
authors.affiliation: CBM-CNRS Orléans , Rue Charles Sadron, 45071 Orléans Cedex 2, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Placide
authors.affiliation: CBM-CNRS Orléans , Rue Charles Sadron, 45071 Orléans Cedex 2, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Petoud
authors.affiliation: CBM-CNRS Orléans , Rue Charles Sadron, 45071 Orléans Cedex 2, France.
authors.forename: Josef
authors.identifier: http://orcid.org/0000-0003-4641-7357
authors.initials: J
authors.lastname: Hamacek