Influence of Ligand Environment Stoichiometry on NIR-Luminescence Efficiency of Sm, Pr and Nd Ions Coordination Compounds.

Six new complexes of the ligand HQ (-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) and Ln ions with emission in the near-infrared (Nd) or visible and near-infrared (Sm, Pr) spectral regions were synthesized and characterized using various methods, including single crystal X-ray diffraction. The study demonstrated that both tris complexes [LnQ(HO)(EtOH)] and tetrakis-acids [HO][LnQ] can be synthesized by varying the synthetic conditions. The photochemical properties of the complexes were investigated experimentally and theoretically using various molecular spectroscopy techniques and Judd-Ofelt theory.

Self-Assembly of a Two-Dimensional Coordination Polymer Based on Silver and Lanthanide Tetrakis-Acylpyrazolonates: An Efficient New Strategy for Suppressing Ligand-to-Metal Charge Transfer Quenching of Europium Luminescence.

A new strategy for the easy polymerization of anionic [Ln(Q)] (HQ-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) into two-dimensional layers of [AgLn(Q)] (Ln = Sm, Eu, Gd, Tb and Dy) is proposed by binding the single molecular anions [Ln(Q)] to silver cations through the coordination of the pyridinic nitrogen atoms of the pyrazolonate rings. The luminescent properties of [AgLn(Q)] have been studied in detail, and it was shown that the previously described low photoluminescence quantum yield (PLQY) of [Eu(Q)] is due to Ligand-To-Metal Charge Transfer (LMCT) quenching, which is effectively suppressed in the heterometallic [AgEu(Q)] polymer. Sensibilization coefficients for HO[Eu(Q)], [AgEu(Q)], and HO[Sm(Q)] complexes (n ≈ 1) were estimated via theoretical analysis (also by using Judd-Ofelt theory for Sm) and PLQY measurements.

OLED Structure Optimization for Pure and Efficient NIR Electroluminescence of Nd Complexes Bearing Fluorinated 1,3-Diketones.

NIR emitting OLEDs (organic light-emitting diodes) with high photoluminescence quantum yields were developed on the basis of fluorinated 1,3-diketonate coordination compounds of the Nd ion. Both thermal evaporation and spin-coating techniques were successfully employed for active layer deposition resulting in electroluminescence quantum yields up to 1.38·10%.

Effect of ancillary ligands on visible and NIR luminescence of Smβ-diketonate complexes.

Two new Sm complexes with pyrazolic β-diketones bearing a CF group acting as main ligands and with 2,2'-bipyridine or 1,10-phenanthroline being the ancillary ligand were studied, and their energy level structure was established. Stark splitting observed in the photoluminescence spectra of the complexes points to their non-cubic symmetry, confirmed by the calculated Judd-Ofelt intensity parameters. Internal quantum yields obtained for the compounds by the Judd-Ofelt calculations were of the order of 5.