Synthesis and Photoluminescence Properties of Heteroleptic Europium(III) Complexes with Appended Carbazole Units

Two europium complexes {Eu-dbm-carb-phen = tris[1-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}-3-{[6-(9H-carbazol-9-yl)- hexoxy]phenyl}propane- 1,3-dione](1, 10-phenanthroline)-europium(III), Eu.dbm.carb.bath = tris[1-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}-3-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}- propane- 1,3-dione] (bathophenanthroline) europium(III) I and their reference compounds were synthesized and characterized. Each complex contains three different chromophores: carbazole (carb), phenanthroline (phen) (or bathophenanthroline, bath) and dibenzoylmethane (dbm) units. The luminescence properties investigated in dichloromethane solution and in solid matrix show that the carbazole moiety is a better sensitizer for the metal-centred emitting states of the Eu(III) ion compared to the dibenzoylmethane and phenanthroline units. Furthermore, the charge-transporting properties of the carbazole moieties appear to be appealing when integrated into the emitting units. Finally, the high number of appended carbazole units confers a strong light-harvesting character to the structure.