Luminescence of praseodymium (III) chelates from two excited states (3P0 and 1D2) and its dependence on ligand triplet state energy

The praseodymium (III) β-diketonate and carboxylate chelates emit visible and infrared luminescence in organic solutions at room temperature. Depending on the position of triplet level of the ligand the ff-emission of Pr3+ was observed either from two excited states (3P0 and 1D2) at 490, 605, 610, 645, 890 and 1060 nm or from the 1D2 state only at 605, 890 and 1060 nm. For all chelates studied, the emission has low quantum yield, e.g. <0.2% for 1D2-luminescence of Pr(TTA)3·2H2O in DMSO.