Excited State Properties of Lanthanide(III) Complexes with a Nonadentate Bispidine Ligand
Laura Abad Galán, Patrick Cieslik, Peter Comba, Michael Gast, Olivier Maury, Lucca Neupert, Amandine Roux, Hubert Wadepohl
Abstract
Abstract Eu III , Tb III , Gd III and Yb III complexes of the nonadentate bispidine derivative L 2 (bispidine=3,7‐diazabicyclo[3.3.1]nonane) were successfully synthesized and their emission properties studied. The X‐ray crystallography reveals full encapsulation by the nonadentate ligand L 2 that enforces to all Ln III cations a common highly symmetrical capped square antiprismatic (CSAPR) coordination geometry (pseudo C 4v symmetry). The well‐resolved identical emission spectra in solid state and in solution confirm equal structures in both media. As therefore expected, this results in long‐lived excited states and high emission quantum yields ([Eu III L 2 ] + , H 2 O, 298 K, τ=1.51 ms, ϕ=0.35; [Tb III L 2 ] + , H 2 O, 298 K, τ=1.95 ms, ϕ=0.68). Together with the very high kinetic and thermodynamic stabilities, these complexes are a possible basis for interesting biological probes.