title: Rare-earth quinolinates: infrared-emitting molecular materials with a rich structural chemistry.
abstract: Near-infrared-emitting rare-earth chelates based on 8-hydroxyquinoline have appeared frequently in recent literature, because they are promising candidates for active components in near-infrared-luminescent optical devices, such as optical amplifiers, organic light-emitting diodes, .... Unfortunately, the absence of a full structural investigation of these rare-earth quinolinates is hampering the further development of rare-earth quinolinate based materials, because the luminescence output cannot be related to the structural properties. After an elaborate structural elucidation of the rare-earth quinolinate chemistry we can conclude that basically three types of structures can be formed, depending on the reaction conditions: tris complexes, corresponding to a 1:3 metal-to-ligand ratio, tetrakis complexes, corresponding to a 1:4 metal-to-ligand ratio, and trimeric complexes, with a 3:8 metal-to-ligand ratio. The intensity of the emitted near-infrared luminescence of the erbium(III) complexes is highest for the tetrakis complexes of the dihalogenated 8-hydroxyquinolinates.
authors.affiliation: Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium. rik.vandeun@chem.kuleuven.ac.be
authors.forename: Rik
authors.initials: R
authors.lastname: Van Deun
authors.forename: Pascal
authors.initials: P
authors.lastname: Fias
authors.forename: Peter
authors.initials: P
authors.lastname: Nockemann
authors.forename: An
authors.initials: A
authors.lastname: Schepers
authors.forename: Tatjana N
authors.initials: TN
authors.lastname: Parac-Vogt
authors.forename: Kristof
authors.initials: K
authors.lastname: Van Hecke
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.forename: Koen
authors.initials: K
authors.lastname: Binnemans