Red Emitting Cerium(III) and Versatile Luminescence Chromaticity of 1D‐Coordination Polymers and Heterobimetallic Ln/AE Pyridylpyrazolate Complexes

Abstract Ten homoleptic lanthanide containing 1D‐coordination polymers, three heterobimetallic lanthanide/alkaline earth complexes as well as two alkaline earth complexes of the formula 1 ∞ [Ln(2‐PyPz) 3 ], [Tb 2 AE(2‐PyPz) 8 ], and [AE(2‐PyPz) 2 (2‐PyPzH) 2 ], Ln=La−Nd, Sm−Ho, AE=Ca, Sr, Ba were obtained by reactions of the lanthanide (Ln) and/or the alkaline earth metals (AE) with the ligand 3‐(2‐pyridyl)pyrazole. Organic melt based and/or solvothermal synthesis results in a redox reaction. The investigated compounds exhibit fair thermal stability up to 400 °C. The Ce 3+ compound exhibits a bright and red 5d‐based broad band emission with a maximum at around 640 nm under UV excitation marking an example of a strong reduction of the exited 5d states of Ce(III). The co‐doping of the Gd‐containing coordination polymers with Eu 3+ and Tb 3+ allows for a shift in the chromaticity from the ion specific 4 f‐based emission colors close to white light emission and thus for a versatile tuning of the chromaticity. The co‐doping of Eu 3+ with Tb 3+ and vice versa shows metal‐to‐metal energy transfer (MMET) between 4 f‐levels of Tb 3+ and Eu 3+ , which influences the tuning of the emission colour.