Sensitised near-infrared emission from lanthanides using an iridium complex as a ligand in heteronuclear Ir(2)Ln arrays

The iridium(III) complex Ir(ppy)(2)(phen5f) [ ppy = 2-phenylpyridinato-N,C(2'), and phen5f = 4,4,5,5,5-pentafluoro-1-(1', 10'-phenanthrolin-2'-yl)-pentane-1,3-dionate] has been synthesised and used as complex ligands to make heteronuclear d-f complexes by the attachment of Ln(NO(3))(3)center dot xH(2)O at the vacant coordination sites in the bridging ligand phen5f. The microanalyses and crystal structure characteristics confirmed the formation of the heteronuclear Ir(2)Ln arrays. The measurement of the lowest triplet state energy level of Ir(ppy) 2(phen5f) indicates that it is suitable for the NIR (near-infrared) lanthanide ions, Nd(III), Yb(III) and Er(III). Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(ppy) 2(phen5f) at an excitation wavelength from 380-490 nm, the characteristic emission spectra of the three Ir2Ln arrays (Ln = Nd, Yb, Er) in both the solid state and in CH(3)CN solution were measured. According to the results, more Ir(III) complexes will be designed for lanthanide NIR emission by the proper combination between the cyclometalated ligand and the tetradentate ancillary ligand.