Ytterbium acetylacetone

A 21 mg (0.017 mmol) octabromtetrapher rlporphyrin was dissolved in 15 rtiL 1,2.4-trichlorbenzene, and then 25 mg (0.053 mmol) ytterbium acetylacetonate (3) was added. The mix was boiled in inert gas flow within 2 h. The solvent was evaporated. Metallocomplex was isolated by column chromatography on a silica gel in the CHCl3-qH50H (9 1) system. Yield 15 mg (59%). UV-vis, 472,611,662 nm. 

The ytterbium acetylacetonate precipitate (3) was isolated on a centrifuge, carefully washed by a distilled water, dried and rectystalhzed from benzene-petroleum ether. 

When carrying out the triple recrystallization of ytterbium acetylacetonate from acetone with water, the formation of a new compound takes place, with a higher temperature of melting (M.p. 179-181°C), with smaller percentage of carbon and hydrogen. The substance does not evaporate in a mass spectrometer under the conditions similar to ytterbium acetylacetonate (3). 

Ytterbium, trinitratotris(dimethyl sulfoxide)-structure, 1, 97 Ytterbium, tris(acetylacetone)(4-ammo-3-penten-stereochemistry, 1,81 Ytterbium complexes acetylacetone, 2,373 dipositive oxidation state hydrated ions, 3,1109 polypyrazolylborates, 2,255 Ytterbium(III) complexes ethyl glycinate, diacetate... 

X 109 and 8. 9 x 109 s 1 for Ndm and Ybm, respectively. Both the above-described in-termolecular mechanism, as well as an intramolecular pathway in the ternary complex with aad which forms in solution, are responsible for the observation of NIR luminescence in these systems. Addition of water to the toluene solutions quenches the NIR luminescence, while it enhances the visible CL emission of the corresponding solution of Eum and Tbm (Voloshin et al., 2000c). Neodymium and ytterbium tris(benzoyltrifluoroacetonates) display the same CL as tta complexes, although for Ybm its intensity is about 2.5 times lower than for the tta chelate. On the other hand, almost no CL is detected for acetylacetonate complexes (Voloshin et al., 2000a). Thermal or photochemical decomposition of aad also triggers CL from [Pr(dpm)3] and Pr(fod)3], both in the visible (from the 3Pi, 3Po, and 1D2 levels) and in the NIR at 850 nm ( Do -> 3F2 transition) and 1100 nm ( D2 3F4 transition). The excited... 

A 0.215 g (5.6x10 mol) ytterbium nitrate was dissolved in 50 rrrL distilled water, when rrrixing 0.2 rrrL acetylacetone in 2 mL ethanol was added arrd then the diluted solution of ammortia was slowly dropped to pH 6-6.5. The white precipitation was isolated by cerrtrifugatiorr, three times washed by distilled water and dried in a vacuum to a constarrt weight Yield 0.2 g (71%). M.p.l32°C. The substance was recrystallized from a berrzene and petroleum ether rrrix, M.p. 142-144°C. IR-spectrurrr, v, cm 3391 (H O), 1616 h 1524 (acac). Mass-spectrurrr, rrr/z 470 (M%... 

The first stage of oirr work was the synthesis of lanthanide elements salts (ytterbium and erbium) in a form of acetylacetonates. The rare-earth elements (REE) complexes in most cases have the coordination number (CN) more than six (7, 8, 9, 10 and even 12). CN of REE ions in complexes with organic poly dentate ligands are high and variable [10]. The reason of this phenomenon lies in the big ionic radius, which decreases from 1.06 A (La " ) to 0.88 A (Lu " ) (the effect of lanthanide compression ). The empty site of the coordination sphere is occupied by other ligands water, hydroxyl ions, etc. In IR-spectrum the hydroxyl ion is characterized by a narrow strip at 3700-3600 cm, it has higher frequency than water. Frequency v of water is located in a region of about 3600-3200 cm". ... 

The value of a pH of ytterbium hydroxide sedimentation and its control during the course of the synthesis are the necessary conditions when receiving ytterbium complexes. Used oxygen-containing bidentate donors (acetylacetone) should be low basic. In this connection the reaction of interaction of ytteibium salts with such ligands can be carried out in neutral and veiy subacidic environments (pH 5-6). 

Acetylacetone was dissolved in a small volume of ethanol, mixed with water solution of ytterbium nitrate and the diluted solution of ammonia when mixing was slowly dropped under a pH control by use of pH-meter. At pH 5.7 the slight turbidity started, and at pH 6.0 the white precipitate was formed. We tried not to raise a pH higher than 6.5 since there can be a replacement of the acetylacetonate residues with a hydroxyl ... 

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