Visible-luminescent lanthanide (LnL) complexes with a highly planar tetradentate ligand were successfully developed for a visible-light solid-state excitation system. L was designed by using two 2-hydroxy-3-(2-pyridinyl)-benzaldehyde molecules bridged by ethylenediamine, which was then coordinated to a series of Ln ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb). From the measurement of single-crystal X-ray analysis of EuL, two phenolic O atoms and two imine N atoms in L were coordinated to the Eu ion, and each π-electronic system took coplanar with the edged-pyridine moiety through an intramolecular hydrogen bond. The enol group on the phenolic skeleton changed to the keto form, and the pyridine was protonated. Thus, intramolecular proton transfer occurred in L after the complexation. Other complexes take isostructure. The space group is P-1, and the c-axis shrinks with decreasing temperature without a phase transition in EuL. The yellow color caused by the planar structure of L can sensitize ff emission by visible light, and the luminescence color of each complex depends on central Ln ions. Furthermore, a phosphorescence band also appeared at rt with ff emission in LnL. Drastic temperature dependence of luminescence was clarified quantitatively.
Theoretical calculations are typically utilized for examining intermetallic interactions. However, to validate theory, experimental confirmation of the existence of these interactions is necessary. We synthesized new heterometallic Ln–Pt complexes, NEt4{[Pt(PhSAc)4]Ln[(PhSAc)4Pt]}·2DMF (Ln: lanthanoid = Gd (1), Tb (2), Dy (3), PhSAc = benzothioacetate, NEt4 = tetraethylammonium), in which both diamagnetic Pt(II) ions interact with the central Ln(III) ion. Typically, these interactions are not detected, because the distance between Ln and Pt atoms (~3.6 Å) is much larger than the covalent radius (~3.3 Å) and ionic radius (~3.10 Å). Pt-LIII resonant inelastic X-ray scattering (RIXS) analysis was conducted to experimentally confirm the unique influence of the hidden Ln–Pt interaction on the luminescence of the Tb–Pt molecule, where the interaction induced emission properties in the Tb and Pt ions, with high quantum yield (59%). Quantum theory of atoms in molecules (QTAIM) analysis was also used to confirm the experimental results. RIXS analysis allowed the identification of several distinctive characteristics of the coordination environment, including the existence of heterometallic interactions, that affected the observed luminescence.
Theoretical calculations are typically utilized for examining intermetallic interactions. However, to validate the theory, experimental confirmation of the existence of these interactions is necessary. We synthesized new heterometallic Ln−Pt complexes, NEt 4 {[Pt(PhSAc) 4 ]Ln[(PhSAc) 4 Pt]}• 2DMF (Ln: lanthanoid = Gd (1), Tb (2), Dy (3), PhSAc = benzothioacetate, NEt 4 = tetraethylammonium), in which both diamagnetic Pt(II) ions interact with the central Ln(III) ion. Typically, these interactions are not detected because the distance between Ln and Pt atoms (∼3.6 Å) is much larger than the covalent radius (∼3.3 Å) and ionic radius (∼3.10 Å). Pt−L III resonant inelastic X-ray scattering (RIXS) analysis was conducted to experimentally confirm the unique influence of the hidden Ln−Pt interaction on the luminescence of the Tb−Pt molecule, where the interaction induced emission properties in the Tb and Pt ions, with high quantum yield (59%). Quantum theory of atoms in molecules (QTAIM) analysis was also used to confirm the experimental results. RIXS analysis allowed the identification of several distinctive characteristics of the coordination environment, including the existence of heterometallic interactions, that affected the observed luminescence.
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