Nowadays, lanthanide complexes, in particular, with β diketones have been intensively studied. This is caused by the possibility of their use as an active layer of organic light emitting diodes (OLEDs) [1], an active medium of tunable lasers, fluorescent labels, and dyes [2]. The largest number of works have focused on europium compounds emitting in the red, as well as on terbium compounds emitting in the green. Samarium, dysprosium, and thulium com pounds are also able to emit in the visible range under certain conditions [3].The luminescence spectrum of Dy 3+ complexes shows two strong lines-the blue line at 480 nm and the yellow line at 572 nm. If their intensities are equal, white light emission is observed. The spectrum of Тm 3+ complexes can contain several lines (478, 650, 770, 790 nm); as a rule, the blue line at 478 nm is the strongest one. Such properties make thulium and dys prosium compounds rather attractive materials for lighting engineering; the emission intensity is, as a rule, low but can be significantly enhanced by rational choice of ligands [4].For Gd 3+ complexes with organic ligands, lumines cence of gadolinium ions in not observed, but at low temperatures (77 K), phosphorescence from the trip let level of the ligand is observed, which enables the determination of its energy.Previously, we reported the synthesis of the bright luminescent europium complex with a new heterocy clic ligand-1,3 bis(1,3 dimethyl 1H pyrazol 4 yl) 1,3 propanedione (HL, 1). In the present work, we summarized data on the synthesis and photophysical properties of Tm, Dy, and Gd derivatives with this ligand.
EXPERIMENTALLigand 1 was purchased from Art Chem GmbH (Campus Berlin Buch). Initial solutions of lanthanide chlorides were prepared by dissolving weighed samples of lanthanide oxides (99.9%, Aldrich) in a small excess of a 20% solution of HCl (special purity grade) and adjusting the volume with water to obtain a 0.5 M solu tion. The other reagents and solvent (for synthesis grade, Acros Organics) were used as purchased.The luminescence spectra of solid samples were recorded on a Perkin Elmer LS 45 spectrofluorimeter in quartz ampoules at room temperature and, with the use of a cryo unit, at 77 K.The absorption spectra of solutions of free ligands and complexes were recorded on a Perkin Elmer Lambda 45 spectrophotometer.Elemental CHN analysis was carried out on a Ele mentar Vario EL Cube automated analyzer. The metal content was determined by titration with EDTA after the acidic decomposition of the complexes.Synthesis. Ligand 1 (0.780 g, 3 mmol) and 0.180 g (1 mmol) of 1,10 phenanthroline (1,10 Phen) were dissolved in 15 mL of ethanol on heating. The solution was filtered, then 3 mL (3 mmol) of a 1 M NaOH solu tion was added, and 1 mmol (2 mL) of a lanthanide chloride solution was introduced dropwise under stir ring. The pH 6.5 was adjusted by adding few drops of a NaOH or acetic acid solution. After that, the solution was kept at 40°С for 4 h and then was left at room tem perature for a day. The resulting mixture w...
