Synthesis, crystal structure, and photoluminescent properties of mononuclear Er(III) and Yb(III) complexes showing near-infrared emission

Abstract

Lanthanide coordination complexes [Er(H3thaea)2](NO3)3·2H2O·2CH3OH (1) and [Yb(H3thaea)2](NO3)3·2H2O·2CH3OH (2) were prepared by the reaction of Er(NO3)3·5H2O or Yb(NO3)3·5H2O with tris(((2-hydroxy-3-methoxybenzyl)amino)ethyl)amine (H3thaea) in methanol. The complexes were characterized by elemental analysis, spectroscopy, photoluminescence, and single crystal X-ray diffraction. The erbium(III) ion of 1 is coordinated by six oxygen atoms of two H3thaea ligands and shows a nearly octahedral geometry structure. The coordinated oxygen atoms are deprotonated (O−) and three secondary nitrogen atoms of H3thaea are protonated ((-CH2)2NH2+). Complex 2 shows almost the same structure to that of 1. Complex 1 exhibits three emission peaks in near IR region due to Er(III) ion at 973, 1013, and 1233 nm, while complex 2 displays one sharp emission at 977 nm with broad band from 920 to 1100 nm due to Yb(III) ion.