3D Microporous Lanthanide-Organic Frameworks Constructed from Left- and Right-Handed Helical Chains: Synthesis, Crystal Structure, and Tunable Photoluminescence

New lanthanide-organic frameworks, [Ln(2)(2,6-NDS)(3)(IP)(H2O)(4)].H2O {Ln = Sm (1), Eu (2), Tb (3); 2,6-NDS = 2,6-Anaphthalenedisulfonate, IP = 1H-imidazo[4,5-f][1,10]-phenanthroline}, were synthesized and characterized. These complexes are isostructural and have three-dimensional structures (3D) composed of a pair of entanglement double helixes. The structure is an open framework with rhombic channels filled with uncoordinated water molecules. The photoluminescence properties of the Sm-III complex (1) and Eu-III/Tb-III-doped complex were explored by adjusting the excitation wavelengths. Interestingly, Sm-III complex 1 generated a white-light emission, whereas the Eu-III/Tb-III-doped complex (Tb0.95Eu0.05) allowed the realization of white-light emission under broad UV wavelengths. An energy transfer for (TbD4EuD0)-D-II5-D-III5 was observed.