Sensitized near-infrared emission of YbIII from an IrIII–YbIII bimetallic complex

A new cyclometalated ligand 1,3-dimethyl-5-phenyl-1H-[1,2,4]-triazole (pdt) was designed and synthesized. And the corresponding IrIII 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 EuIII. The bimetallic complex [(pdt)2Ir(μ-phen5f)YbCl2 · 2CH3CH2OH · H2O]Cl was synthesized by the approach of “complexes as ligands”. Data showed that the emission quenching was observed in the solid state when the IrIII–YbIII complex was compared with the IrIII complex, which implied that energy transfer might occur from IrIII complex-ligand to YbIII ion. Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(pdt)2(phen5f), the characteristic emission of YbIII was obtained with the peak around 978 nm.

Graphical abstractAn IrIII complex with a new cyclometalated ligand and the corresponding IrIII–YbIII bimetallic complex by the approach of “complexes as ligands” were synthesized. The near-infrared emission from YbIII was obtained by the efficient energy transfer from the IrIII center.Figure optionsDownload full-size imageDownload as PowerPoint slide