Three ytterbium(III) complexes with aromatic N‐donors: Synthesis, structure, photophysical properties and thermal stability

Three new ytterbium complexes of the general formula [YbL2Cl3] with expanded aromatic N-donor based ligands based on 1,10-phenanthroline (dipyrido-[3,2-f : 2 ',3 '-h]-quinoxaline (DPQ), 2-methyldipyrido-[3,2-f : 2 ',3 '-h]-quinoxaline (MeDPQ) and 1,10-phenanthroline (Phen)) were synthesized and characterized using different structural analysis, simultaneous thermal analysis, and photoluminescence, and UV-Vis-NIR spectroscopy. The compounds were obtained by the reaction of ytterbium(III) chloride hexahydrate and the corresponding aromatic N-donor through substitution of water from the coordination sphere with the organic ligand. Photoluminescence studies revealed Yb3+-based NIR emission of the corresponding compounds with following luminescence lifetimes [Yb(DPQ)(2)Cl-3] (1) - 7.8(1) mu s, [Yb(MeDPQ)(2)Cl-3] (2) - 9.3(1) mu s, [Yb(Phen)(2)Cl-3] (3) - 8.7(1) mu s. The resulting complexes are stable under atmospheric conditions, exhibit good thermal stability, and start to oxidize only at sufficiently high temperatures: (1) at 470 degrees C, (2) at 430 degrees C, and (3) at 395 degrees C.