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

Abstract

AbstractThree 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)2Cl3] (1) – 7.8(1) μs, [Yb(MeDPQ)2Cl3] (2) – 9.3(1) μs, [Yb(Phen)2Cl3] (3) – 8.7(1) μs. The resulting complexes are stable under atmospheric conditions, exhibit good thermal stability, and start to oxidize only at sufficiently high temperatures: (1) at 470 °C, (2) at 430 °C, and (3) at 395 °C.