Photoluminescent one-dimensional coordination polymers from suitable pyridine antenna and LnCl3 for visible and near-IR emission

The series of one-dimensional coordination polymers ∞1[LnCl3(bipy)(py)2]·py [bipy = 4,4′-bipyridine, py = pyridine; Ln = Gd, Tb, Dy, Ho, Er, Yb] as well as ∞1[Lu2Cl5(bipy)2(py)4]∞1[LuCl4(bipy)] were synthesized by the reactions of anhydrous LnCl3 with bipy and py. The formation of extended zigzag chains and saltlike band structures with cationic and anionic strands is observed. Pyridine and 4,4′-bipyridine ligands serve as suitable antennas for lanthanide-based luminescence in the visible and near-infrared range through effective sensitization by the ligands followed by emission through the emissive intra-4f transitions of the Ln3+ (Tb3+, Dy3+, Er3+, Yb3+) ions. For ∞1[GdCl3(bipy)(py)2]·py, phosphorescence of the coordinated 4,4′-bipyridine ligand with excitation-dependent chromaticity leads to ligand-based emission in the visible range. These processes cannot be observed for the free ligand. The coordination polymers also extend the range of photoluminescence properties of related complexes and metal–organic frameworks (MOFs) and show high efficiency with a quantum yield of 86 % for the Tb3+ compound.