title: Modulating the photophysical properties of azamacrocyclic europium complexes with charge-transfer antenna chromophores.
abstract: Two europium complexes with bis(bipyridine) azamacrocyclic ligands featuring pendant arms with or without π-conjugated donor groups are synthesized and fully characterized by theoretical calculations and NMR spectroscopy. Their photophysical properties, including two-photon absorption, are investigated in water and in various organic solvents. The nonfunctionalized ligand gives highly water-stable europium complexes featuring bright luminescence properties but poor two-photon absorption cross sections. On the other hand, the europium complex with an extended conjugated antenna ligand presents a two-photon absorption cross section of 45 GM at 720 nm but is poorly luminescent in water. A detailed solvent-dependent photophysical study indicates that this luminescence quenching is not due to the direct coordination of O-H vibrators to the metal center but to the increase of nonradiative processes in a protic solvent induced by an internal isomerization equilibrium.
authors.affiliation: Cisbio Bioassays, Parc Marcel Boiteux, BP 84175, 30204 Bagnols-sur-Cèze Cedex, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Bourdolle
authors.forename: Mustapha
authors.initials: M
authors.lastname: Allali
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Mulatier
authors.forename: Boris
authors.initials: B
authors.lastname: Le Guennic
authors.forename: Jurriaan M
authors.initials: JM
authors.lastname: Zwier
authors.forename: Patrice L
authors.initials: PL
authors.lastname: Baldeck
authors.forename: Jean-Claude G
authors.initials: JC
authors.lastname: Bünzli
authors.forename: Chantal
authors.initials: C
authors.lastname: Andraud
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamarque
authors.forename: Olivier
authors.initials: O
authors.lastname: Maury
mesh_terms: D001372:Aza Compounds / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005063:Europium / Q000737:chemistry*; D047028:Macrocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes; D013237:Stereoisomerism
chemical_list: D001372:Aza Compounds; D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D005063:Europium