Variable Luminescence and Chromaticity of Homoleptic Frameworks of the Lanthanides together with Pyridylpyrazolates

Homoleptic, 3D coordination polymers of the formula (33) (∞)[Ln(3‐PyPz)(3)] and (3) (∞)[Ln(4‐PyPz)(3)], (3‐PyPz)(−)=3‐(3‐pyridyl)pyrazolate anion, (4‐PyPz)(−)=3‐(4‐pyridyl)pyrazolate anion, both C(8)H(6)N(3) (−), Ln=Sm, Eu, Gd, Tb, Dy, were obtained as highly luminescent frameworks by reaction of the lanthanide metals (Ln) with the aromatic heterocyclic amine ligands 3‐PyPzH and 4‐PyPzH. The compounds form two isotypic series of 3D coordination polymers and exhibit fair thermal stability up to 360 °C. The luminescence properties of all ten compounds were determined in the solid state, with an antenna effect through ligand–metal energy transfer leading to high efficiency of the luminescence displayed by good quantum yields of up to 74 %. The emission is mainly based on ion‐specific lanthanide‐dependent intra 4 f–4 f transitions for Tb(3+): green, Dy(3+): yellow, Sm(3+): orange‐red, Eu(3+): red. For the Gd(3+)‐containing compounds, the yellow emission of ligand triplet‐based phosphorescence is observed at room temperature and 77 K. Co doping of the Gd‐containing frameworks with Eu(3+) and Tb(3+) allow further shifting of the chromaticity towards white light emission.