Unique lanthanide frameworks with 63 topology based on 1,5-naphthalenedisulfonate and 1H-imidazo[4,5-f][1,10]-phenanthroline: syntheses, crystal structure, photoluminescence, and white light emission

Novel lanthanide–organic frameworks {[Ln2(1,5-NDS)3(IP)4(H2O)2]·9H2O}n (Ln = Pr 1, Sm 2, Eu 3, Gd 4, Dy 5, Tb 6; 1,5-NDS = 1,5-naphthalenedisulfonate, and IP = 1H-imidazo[4,5-f][1,10]-phenanthroline) were synthesized and characterized. The complexes possess unique 2D architectures with 63 topology, and their structures consist of three-connected uninodal chain-layer framework with helical characteristics. Complexes 1, 4, 5, and 6 show ligand-based fluorescence, whereas complexes 2 and 3 show typical emission with 4f–4f transitions for Ln(III) ions. The Sm(III) framework (2) exhibits white light emission. The two-component Ln(III) (Gd, Dy, and Pr)-doped Eu(III) complexes also exhibit white light emission. When the Gd(III) ion is incorporated into the Eu(III) framework with arbitrary ratios of Gd : Eu, white light emission is achieved.