Synthesis, Structures, and Luminescent Properties of Lanthanide Complexes with Triphenylphospine Oxide

Seven lanthanide complexes [Ln(OPPh3) 3(NO3)(3)] (1-3) (OPPh3 = triphenylphosphine oxide, Ln = Nd, Sm, Gd), [Dy(OPPh3)(4)(NO3)(2)](NO3) (4), [Ln(OPPh3)(3)(NO3)(3)](2) (5-7) (Ln = Pr, Eu, Gd) were synthesized by the reactions of different lanthanide salts and OPPh3 ligand in the air. These complexes were characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR and fluorescence spectra. Structure analysis shows that complexes 1-4 are mononuclear complexes formed by OPPh3 ligands and nitrates. The asymmetric units of complexes 5-7 consist of two crystallographic-separate molecules. Complex 1 is self-assembled to construct a 2D layer-structure of (4,4) net topology by hydrogen bond interactions. The other complexes show a 1D chain-like structure that was assembled by OPPh3 ligands and nitrate ions through C-H center dot center dot center dot O interactions. Solid emission spectra of compounds 4 and 6 are assigned to the characteristic fluorescence of Tb3+ (lambda(em) = 480, 574 nm) and Eu3+ (lambda(em) = 552, 593, 619, 668 nm).