A Family of Highly Emissive Lanthanide Complexes Constructed with 6-(Diphenylphosphoryl)picolinate.

We report a novel family of lanthanide complexes Ln(DPPOP)3 (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Er, and Yb) employing anionic tridentate (O∧N∧O) ligand 6-(diphenylphosphoryl)picolinate (DPPOP). Crystal structures of the complexes reveal that each lanthanide ion is nine-coordinated by three tridentate ligands. In the crystals, 1D channels are found, which can absorb and eliminate water reversibly. DPPOP possesses high triplet energy and can sensitize a series of lanthanide ions. An energy transfer mechanism is proposed through the higher excited states of the lanthanide ions. In the solid state, remarkably high quantum yields in the visible range are obtained: 81% for Eu(III), 97% for Tb(III), 13% for Dy(III), and 4% for Sm(III) complex.