Structure and sensitized near-infrared luminescence of Yb(III) complexes with sulfonylamidophosphate type ligand

A series of new lanthanide complexes with dimethyl(phenylsulfonyl)amidophosphate (HSP) was synthesized ({Na[Ln(SP)(4)]}(n) (Ln1), [Ln(SP)(3)phen] (Ln2) and [Ln(SP)(3)bpy]center dot H2O (Ln3) (where Ln = Gd-III, Er-III, Yb-III and Lu-III; phen = 1,10-phenantroline; and bpy = 2,2'-bipyridine) and the crystal structures of [Er(SP)(3)phen] and [Yb(SP)(3)bpy]center dot H2O were resolved. Absorption (at 295, 4 K), emission (at 295, 77, 4 K) and IR (at 295 K) spectra as well as luminescence decay time measurements were used to characterize the photophysical properties of single crystals. Effective energy transfer from a [SP](-) ligand to the Yb-III ion was demonstrated despite a large energy gap Delta E = E-trip - E-2F5/2. Replacing one molecule of the [SP](-) ligand with the phen or bpy molecule caused reduction of the emission decay time from 35 mu s for Yb1 to 20 and 15.5 mu s for Yb2 and Yb3, respectively at the temperature of 295 K. Using the absorption spectra tau(rad) (1.1 ms-Yb1, 943 mu s-Yb2 and 914 mu s-Yb3) and Q(Ln)(Ln) (3.14%-Yb1, 2.19%-Yb2, 1.64%-Yb3) were estimated. On the basis of low temperature, high-resolution absorption and luminescence spectra, the ligand-field splittings of the excited and ground states of Yb-III complexes were determined. (C) 2010 Elsevier B.V. All rights reserved.