Tris‐dipicolinate Lanthanide Complexes: Influence of the Second Hydration Sphere on the Solid‐State Luminescence Properties

Abstract A series of tris‐dipicolinate europium complexes featuring different complexes has been prepared, and their photophysical study has been performed in the solid state highlighting the crucial role of second sphere water molecules. The non‐radiative deactivation constant (k nr ) varies significantly with the number of interstitial water molecules and their distance to the europium emitting center. The complex (NBu 4 ) 3 [Eu(DPA) 3 ], featuring the most lipophilic cation, exhibits excellent solubility and remarkable photophysical properties in aprotic solvents.