Europium spectroscopy

Diorganotin(IV) complexes with 4//-pyrido[l,2-n]pyrimidin-4-ones 109 (96MI4), complexes of 2-methyl- and 2-methyl-8-nitro-9-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-ones with Ag(I), Cu(II), Ni(II), Co(II), and Mn(II) ions (00MI23), 2,4-dimethyl-9-hydroxypyrido[l, 2-n]pyrimidinium perchlorate and its complexes with prasedynium, neodymium, samarium and europium (00MI24) were characterized by UV spectroscopy. 

M. J. Khosravi and E. P. Diamandis, Immunofluorometry of choriogonadotropin by time-resolved fluorescence spectroscopy, with anew europium chelate as label, Clin. Chem. 33, 1994-1999 (1987). 

Europium is used for the capture of thermal neutrons for nuclear control rods in atomic power stations. Thermal neutron absorption of the natural mixture of europium isotopes is 4,600 barns. While its salts are used in coatings for cathode ray tubes in color televisions, organoderivatives are used in NMR spectroscopy. 

Trivalent europium is an excellent ionic probe for materials and its luminescence properties are extensively studied. Eu is one of the mostly informative elements in mineralogy, especially when the ratio Eu /Eu may be assessed. Both oxidation states are luminescent, but the hnes of Eu in minerals are usually very weak and concealed by other centers. By steady state liuninescence spectroscopy its luminescence has been confidently detected only in scheehte and anhydrite (Tarashchan 1978 Gorobets and Rogojine 2001). 

Divalent europium is detected in apatite as a shoulder of Ce luminescence when studied by steady-state spectroscopy (Tarashchan and Marfunin 1969 ... 

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]. 

Cario, L., Lefond, A., Palvadeau, A., Deudon, P., and Meerschault, C. (1999). Evidence of a mixed valence state for europium in the misfit layer compound [(EuS)i.5]i. i5NbS2 by means of a superspace structural determination, Mossbauer spectroscopy and magnetic measurements. /. Solid State Chem. 147, 58-67. 

For those complexes where the chromophore is not coordinated to the metal center directly, the orientation of the chromophore is important to ensure efficient energy transfer. The series of ligands L29-L32 were investigated for correlations between structural parameters found in the solid state (see, for example, Fig. 12) and solution (by NMR spectroscopy) and photophysical properties (69,70). It was found that both chromophore-metal separation and the angle of orientation have a direct influence on the quantum yield of the europium complexes. For example, the difference in quantum yield between [Eu(L29)]3+ and [Eu(L30)]3+ (0.06 and 0.02, respectively) cannot be attributed solely to the chromophore-metal separation, so may also depend on the better orientation of the chromophore in the L29 system as measured by the angle a between the metal center, the amide nitrogen atom, and the center of the phenyl ring. 

There has been to some degree the belief that Mossbauer spectroscopy, although in principle an ideal technique for catalyst studies, for practical purposes can only be applied to problems in catalysis if the catalyst contains either iron or tin. Therefore, one of the main purposes of this review is to show how Mossbauer spectroscopy can be directly extended to many additional Mossbauer atoms or isotopes (such as antimony, europium, nickel, ruthenium, gold, and tungsten) and, perhaps more importantly, how the technique can be extended to obtain information about systems that do not contain a Mossbauer atom. ... 

Energy dispersive X-ray (EDX) analyses (data in Tables l-lll) represent semiquantitative analyses of elemental distributions of vanadium, europium and elements of the zeolite and gel structure. EDX data arise from about 2 mm area and, therefore, are more indicative of bulk analyses than surface analyses such as the data obtained by X-ray photoelectron spectroscopy. 

Addition of the same NHC to Eu(thd)3 (thd — tetramethylheptanedioate) affords the europium(III) adduct Eu(thd)3(NHC). The europium-NHC bond distance of 2.663(4) A is shorter than that of the samarium(II) complex and is consistent with the higher oxidation state of the lanthanide centre. The yttrium(III) analogue was also prepared and characterised by NMR spectroscopy. The C2 carbon resonates at 199 ppm in the 13C NMR spectrum, with a yc coupling constant of 33 Hz. This indicates that the NHC remains bound to the metal centre in solution and does not dissociate on the NMR timescale. 

Figure 2.43 (a) [Lns] clusters, hydrogen atoms have been removed for clarity (b) view of the cluster where ligands have been removed for clarity [77]. (Reproduced from S. Petit, F. Baril-Robert, G. Pilet, C. Reber and D. Luneau, Luminescence spectroscopy of europium(III) and terbium(III) penta-, octa-and nonanuclear clusters with fS-diketonate ligands, Dalton Transactions, 34, 6809-6815, 2009, by permission of the Royal Society of Chemistry.)... 

Petit, S., Baril-Robert, F., Pilet, G, etal (2009) Luminescence spectroscopy of europium(lll) and terbium(lll) penta-, octa- and nonanuclear clusters widi -diketonate ligands. Dalton Transactions, 6809—6815. 

Chauvin, A.-S., Gumy, F., Imbert, D., and BunzU, J.-C.G (2004) Europium and terbium tris(dipicolinates) as secondary standards for quantum yield determination. Spectroscopy Letters, 37 (5), 517-532. 

Huskowska, E., Turowska-Tyrk, I., Legendziewicz, J., and Glowiak, T. (1998) Two high and low symmetry europium complexes with L-proline spectroscopy and structure. Journal of Alloys and Compounds, 275-277, 852-858. 

There is the potential with some substrates that the Lewis acidity of the lanthanide ion can catalyze a reaction. For example, the addition of Eu(hfc)3 to a racemic mixture of dimethylpenta-2,3-dienoates (39) caused an enrichment of the (5 )-isomer °. Over nine days the mixture converted to an 89 11 mixture. Lanthanide tris( S-diketonates) are well known catalysts for Diels-Alder reactions, and NMR spectroscopy of the reactants with Eu(hfc)3 was used to understand the stereoselectivity of the europium-catalyzed cycloadditions . ... 

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