title: Self-assembly of a helical zinc-europium complex: speciation in aqueous solution and luminescence.
abstract: Two new tridentate(NNO)-bidentate(NN) compartmental ligands, HL(5) and HL(6), are synthesized from pyridine and benzimidazole synthons. They react in aqueous solution under physiological conditions with Zn(II), Ln(III), or a mixture thereof, to yield complexes of different stoichiometries, 1:3, 2:2, 2:3, 1:1:3, the speciation of which is established by UV-visible titrations and ESI mass spectrometry. Photophysical studies of the Eu(III)-containing solutions in Tris-HCl 0.1 M (pH = 7.4) show that lanthanide luminescence arises from a unique N6O3 coordination site with pseudo D 3 symmetry. Relevant parameters such as crystal field splitting, lifetime, radiative lifetime, and intrinsic quantum yield perfectly match those reported for dinuclear 4f-4f helicates in which the Eu(III) ion has the same coordination environment.
authors.affiliation: Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Deiters
authors.affiliation: Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland ; Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301 Orléans, France.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Eliseeva
authors.affiliation: Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland ; Department of Advanced Materials Chemistry, WCU Center for Next Generation Photovoltaic Systems, Korea University Sejong-si, South Korea.
authors.forename: Jean-Claude G
authors.initials: JC
authors.lastname: Bünzli
keywords: bimetallic; dinuclear; helicates; lanthanides; luminescence; rare earths; self-assembly; stability constant