Novel Stoichiometrically Erbium−Ytterbium Cocrystalline Complex Exhibiting Enhanced Near-Infrared Luminescence

Abstract

Three beta-diketonate complexes of erbium and ytterbium, Er(HFA)3(TPPO)3, Yb(HFA)3(TPPO)3, and Er(1/2)Yb(1/)(2)(HFA)3(TPPO)2 (HFA = hexafluoroacetylacetonate, TPPO = triphenylphosphine oxide) are synthesized and structurally characterized, and their luminescent properties are examined in detail. Compared with monometallic complexes Er(HFA)3(TPPO)3 and Er(HFA)3(TPPO)3, the stoichiometrically Er-Yb cocrystalline complex Er(1/2)Yb(1/2)(HFA)3(TPPO)2 exhibits special indirect near-infrared (NIR) luminescence with the acceptor and sensitizer (donor) coexisting in a single crystal. Of interest is that the NIR luminescence of the erbium ion in Er(1/2)Yb(1/2)(HFA)3(TPPO)2 is significantly enhanced because of the coexistence of the ytterbium ion through the energy-transfer between the ytterbium and erbium ions. The estimated donor-acceptor energy-transfer critical radii R(C,DA), obtained from the Förster model, are in good agreement with those determined from the single X-ray crystal structure, confirming the dipole-dipole character for such a Yb-Er energy-transfer process.

A new tetrakis β-diketone ligand for NIR emitting LnIII ions: luminescent doped PMMA films and flexible resins for advanced photonic applications

“…Fluorinated b-diketones are one among the most studied antenna molecules for NIR emitting Ln III ions, in view of the minimum number of C-H vibrators present; however the electron attractive nature of the C-F bonds oen reduces the coordination ability of these molecules. 13,14 Moreover, in most of the reports, bidentate b-diketonates result in the formation of neutral tris Ln III complexes with the metal coordination sphere completed by either solvent molecules with O-H vibrators or neutral donors with large numbers of C-H oscillators.…”

Novel Erbium(III) and Ytterbium(III)-based materials for Optoelectronic and Telecommunication Applications

“…Compared to Er 2 (benzoate) 6 (phen) 2 , the NIR luminescence of the erbium ion in the Er 1.4 Yb 0.6 (benzoate) 6 (phen) 2 adduct is enhanced, excited at both 320 and 975 nm, indicating an efficient energy transfer from Yb 3+ to Er 3+ ( Figure 132). [197] Similar results had already been presented by Zhong et al [199] in 2006, reporting another stoichiometrically Er-Yb cocrystalline complex Er 1/2 Yb 1/2 (HFA) 3 (TPPO) 2 (HFA=hexafluoroacetylacetonate, TPPO=triphenylphosphine oxide), but again no structural data was provided and only PL spectra were presented. The sensitization mechanism ( Figure 133) is analogous to that of Song et al's complexes.…”

“…NIR PL spectra of bulky microcrystalline powders of complexes Er 1.4 Yb 0.6 (benzoate) 6 (phen) 2 and Er 2 (benzoate) 6 (phen) 2 around 1535 nm, excited at 975 nm at room temperature [197] Figure 133. Schematic diagram for sensitization mechanism of the Er 3+ ion by Yb 3+ ion or HFA ligand [199] 3. [204,205].…”

Small Molecule Luminescent Lanthanide Ion Complexes - Photophysical Characterization and Recent Developments

“…The intrinsic quantum yields were determined from the radiative lifetimes of 2 and 14 ms for Yb and Er, respectively. Quantum efficiencies of 4.46% for Yb(III) in the monometallic and 4.19% in the the mixed metal complex as well as 0.43% and 0.44% for Er(III) in the monometallic and bimetallic complexes, respectively, were determined [86].…”

“…(12). Structure of complex of Er(III) with hexafluoroacetylacetonato (hfac) and triphenylphosphine oxide (TPO) as ligands, isolated by Zhong et al [86]. number of 8 and is in a square antiprismatic coordination environment, which is slightly distorted towards bicapped trigonal prism.…”