Highly luminescent diphenyl-N-benzoylamidophosphate based lanthanide tetrakis-complexes

Diphenyl-N-benzoylamidophosphate (HL) was structurally characterized and used as ligand in synthesis of a series of new lanthanide tetrakis-complexes of general formula PPh4[LnL4] (Ln = La, Nd, Eu, Gd, Tb). X-Ray diffraction studies of compound PPh4[GdL4] reveal that the lanthanide ion is surrounded by four chelating CAPh ligands forming the complex anion with CN 8 for LnIII. Besides electrostatic interaction, the tetraphenylphosphonium cation forms weak contacts with CAPh ligands of the neighboring tetrakis anions. The IR, absorption, emission and excitation spectra at 298 K and 77 K, as well as thermal gravimetric analyses were used to characterize the complexes. PPh4[EuL4] and PPh4[TbL4] compounds display intense respectively red and green photo- and triboluminescence. The europium complex PPh4[EuL4] photoemission is characterized by decay time over millisecond, rather high intrinsic quantum yield - 74% and overall quantum yield - 56%.