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

Abstract

A series of new lanthanide complexes with dimethyl(phenylsulfonyl)amidophosphate (H SP) was synthesized ({Na[Ln(SP) 4]} n ( Ln1), [Ln(SP) 3phen] ( Ln2) and [Ln(SP) 3bpy]·H 2O ( 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) 3phen] and [Yb(SP) 3bpy]·H 2O 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 Δ E = E trip − E 2 F 5 / 2 . Replacing one molecule of the [SP] − ligand with the phen or bpy molecule caused reduction of the emission decay time from 35 μs for Yb1 to 20 and 15.5 μs for Yb2 and Yb3, respectively at the temperature of 295 K. Using the absorption spectra τ rad (1.1 ms— Yb1, 943 μs— Yb2 and 914 μs— 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.