Sensitized near-infrared emission of Yb III from an Ir III–Yb III bimetallic complex

Abstract

A new cyclometalated ligand 1,3-dimethyl-5-phenyl-1H-[1,2,4]-triazole (pdt) was designed and synthesized. And the corresponding Ir III complex Ir(pdt) 2(phen5f) (phen5f stands for 4,4,5,5,5-pentafluoro-1-(1′,10′-phenanthrolin-2′-yl)-pentane-1,3-dionate) was obtained. According to the measurement of the lowest triplet state energy level of Ir(pdt) 2(phen5f), it is suitable for sensitizing NIR (near-infrared) lanthanide ions instead of Eu III. The bimetallic complex [(pdt) 2Ir(μ-phen5f)YbCl 2 · 2CH 3CH 2OH · H 2O]Cl was synthesized by the approach of “complexes as ligands”. Data showed that the emission quenching was observed in the solid state when the Ir III–Yb III complex was compared with the Ir III complex, which implied that energy transfer might occur from Ir III complex-ligand to Yb III ion. Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(pdt) 2(phen5f), the characteristic emission of Yb III was obtained with the peak around 978 nm.