A series of N⁁N,O⁁O-bridging ligands based on substituted 1-(pyridin-2-yl)-3-methyl-5-pyrazolone and their corresponding heteroleptic iridium(III) complexes as well as Ir–Eu bimetallic complexes were synthesized and fully characterized. The influence of the triplet energy levels of the bridging ligands on the energytransfer (ET) process from the Ir(III) complexes to Eu(III) ions in solution was investigated