Europium derivatives

The product was shown to be the THE adduct, but a later modification of the procedure by E. 0. Fischer and H. Fischer (99), using benzene or diethyl ether in place of THE and the potassium salt in place of the sodium salt of cyclopentadiene, produced solvent-free complexes of Tb, Ho, Tm and Lu. The remaining tricyclopentadienides have since been made by various workers using similar methods (53, 100, 101). All of the complexes behave similarly. They are very air- and moisture-sensitive, are stable to heat, and sublime, except for the europium derivative, at elevated temperatures. They are insoluble in cyclohexane, benzene... 

Lin Z (2004) Time-resolved fluorescence-based europium-derived probes for peroxidase bioassays, citrate cycle imaging and chirality sensing. PhD thesis, University of Regensburg... 

Nine derivatives of 1, [RSb9W2i086]16 (R = La-Gd, Dy, Yb), have been isolated and characterized by elemental analysis, magnetic susceptibility, and infrared spectra. The four-line 183W-NMR spectrum of the lanthanum derivative is consistent with the D3h symmetry of the parent structure, but the emission spectrum of the europium derivative suggests a lower symmetry in the solid state (Liu et al., 1992). No structural determinations of these derivatives have yet been reported. 

The most useful preparative method for the europium derivative is shown (7). The chloroamide of europium (III) is... 

Infrared spectra show a y(CH) vibration for the europium derivative at 739 cm and for Cp2Yb at 750 cm" (E.O. Fischer and H. Fischer, 1965b) this is interpreted as indicative of ionic nature for these compounds. Eu MOssbauer spectra of CpjEu gave an isomeric shift of —1.32 cm s relative to EuFj, demonstrating that this compound is nearly equal in covalency to EUCI2 (Brix et al., 1964 Hufner et al., 1965). 

The typical oxidation state of REM in organoderivatives is a trivalent state. Compounds with a Ln ion were obtained for all HI group metals. In the case of samarium, europium and ytterbium the compounds with the divalent metal are known. The europium derivatives are the most stable among them. 

Europium(TTI) salts are typical lanthanide derivatives. Europium(ll) salts are pale yellow in colour and are strong reducing agents but stable in water. EuX2 are prepared from EuX -hEu (X=C1, Br, I) or EuFa + Ca EuCl2 forms a dihydrale. EUSO4 is prepared by electrolytic reduction of Eu(III) in sulphuric acid. Eu(II) is probably the most stable +2 stale of the lanthanides... 

Europium - the atomic number is 63 and the chemical symbol is Eu. The name derives from the continent of Europe . It was separated from the mineral samaria in magnesium-samarium nitrate by the French chemist Eugene-Anatole Demar9ay in 1896. It was also first isolated by Demar ay in 1901. 

Samarium - the atomic number is 62 and the chemical symbol is Sm. The name derives from the mineral Samarskite, in which it was found and which had been named for Colonel von Samarski , a Russian mine official. It was originally discovered in 1878 by the Swiss chemist Marc Delafontaine, who called it decipium. It was also discovered by the French chemist Paul-Emile Lecoq de Boisbaudran in 1879. In 1881, Delafontaine determined that his decipium could be resolved into two elements, one of which was identical to Boisbaudran s samarium. In 1901, the French chemist Eugene-Anatole Demar9ay showed that this samarium earth also contained europium. 

More insight into the reasons for magnetism of derivatives may be obtained by a closer look at other recently discovered ferromagnetic Cjo materials, which include complexes of cobaltocene with a CgQ-derivative [156, 157], but also metal complexes with europium [175-177] or cerium [178-180] or pure C q in a polymeric modification [181-183]. 

ETL materials that are used most often are emissive metal complexes, especially aluminium but also beryllium and lanthanides such as europium and terbinm, of ligands such as 8-hydroxyquinoUne, benzoquinolines and phenanthroUne, whilst other effective compounds inclnde extended conjugated compounds, e.g. distyrylarylene derivatives. Some ETL materials are chosen because they are non-emissive to act as combined ET and hole blocking layers. A selection of these ETL materials is illustrated in Figure 3.35. 

Europium(III) only exhibits moderate downfield shifts but, significantly, line-broadening is small, while the reverse is true for ytterbium(III). Praseodymium(III) induces upfield shifts with moderate line-broadening. The most popular reagents are derived from europium(III). 

The LSR itself consists of a lanthanide ion, commonly europium (Eu3 + ), praseodymium (Pr3+) or ytterbium (Yb3+), and three /1-diketone anions with alkyl or perfluoroalkyl groups Rl and R2 as ligands. Perdeuterated LSRs, which do not give H signals, are commercially available. Incorporation of chiral /J-diketone ligands, mostly derived from substituted camphors, allows chiral recognition. 

Reaction of the chiral lithium enolate of meso-2,6-dimethylcyclohexanone (6), generated by deprotonation with (R)-l-phenylethylamine and (/ )-camphor/(R)-l-phenylethylaniine derived chiral lithium amides (Table 1, entries 17 and 64) with 3-bromopropene, leads to homoallyl ketones of opposite absolute configuration in acceptable yield with poor to modest enantiomeric excess14, which can be determined directly by H-NMR spectroscopy in the presence of tris [3-(heptafluorohydroxymethylene)-D-camphorato]europium(III) [Eu(hfc)3]. 

These corrections, whilst applicable to a variety of systems, were determined for use with cyclen derivatives. A more wide ranging correction for q values of europium complexes has been postulated by Supkowski and Horrocks (25), using data for 25 complexes taken from the literature. Their new equation is ... 

The unsymmetrical derivative, L2, in which one benzimidazole group is replaced by a 2-pyridyl moiety, and its complexes with europium and terbium have been further studied for their photophysical properties (37). The coordinated nitrate anions in the [ ( 2)( ) ]... 

Recently, a series of derivative ligands, [L19]4-—[L23]4-, has been reported (32,62), where the acetophenone chromophore in [L18]4- is replaced by a dipyrazolylpyridine chromophore. These form lanthanide complexes that are stable in aqueous solution, and which possess very promising photophysical attributes. The europium and terbium complexes of all these ligands have long lifetimes (1.3-1.4 ms for europium and 2.3-2.8 ms for terbium) in water that are largely unchanged by solvent deuteration, indicating the effective exclusion of solvent from the primary coordination sphere. 

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