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Uranyl complex dissolved in room-temperature ionic liquids has diagnostic absorption and emission spectra that has allowed the identification of the symmetry and geometry of the complex. The uranyl complexes are examined in imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids.

The synthesis and characterization of near-infrared (NIR) emitting complexes of Nd(III), Er(III) and Yd(III) based on hexacoordinate lanthanide ions with an aryl functionalized imidodiphosphinate ligand, tpip, are described. The results indicate the effective shielding of the lanthanide by the twelve phenyl groups of the tpip ligands and the reduction of high-energy vibrations in close proximity to the lanthanide, which are the two important features in the design of NIR emitting lanthanide complexes.

The syntheses, structures and spectroscopic properties of the two new rare-earth metal halide ortho-oxomolybdates YF[Mo[O.sub.4]] and YCl[Mo[O.sub.4]] are reported. Both structures were found to contain [[Y.sub.2][X.sub.2]].sup.4+] units in the shape of planar rhombuses, while the [Eu.sup.3+]-doped fluoride derivatives exhibited red luminescence.

The complex formation of the uranyl ion with chloride ions in acetonitrile is examined by factor analysis of ultraviolet-visible absorption and U [L.sub.3] edge EXAFS (extended X-ray absorption fine structure) spectra. The U(VI) coordination of the solution species [U[O.sub.2][Cl.sub.2]([H.sub.2]O)[(MeCN).sub.2]] has changed during the crystallization of replacing one MeCN molecule with a bridging [[mu].sub.3].O atom in the tetramer.

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline ([Fc.sub.2]phen) and ferrocenoyltrifluoroacetone (Hilta) is used to synthesize ferrocene-containing rate earth beta-diketonate complexes. It is found that the presence of the ferrocene groups makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents.

The unique absorption properties of the 9-hydroxyphenalen-1-one (HPHN) ligand are explored to obtain visible-light-sensitizable rare-earth complexes in 1:3 and 1:4 metal-to-ligand ratios. The X-ray crystal structures of the tris complexes have shown solvent coordination to the central rare-earth ion, whereas in the tetrakis complexes, the four [PHN.sup.-] ligands form a protective shield around the central ion, preventing small solvent molecules from coordinating to the rare-earth ion, at least in the solid state.

A study reports the first lanthanide-containing ionic liquids based on the 1-butyl-3-methylimidazolium (BMIM) cation and lanthanide thiocyanate anions of the general formula [[Ln[(NCS).sub.x][(H2O).sub.y].sup.3-x]. The compounds are transparent liquids at room temperature and the crystal structure of [BMMIM.sub.4][La(NCS)7](H2O)] indicates that hydrogen bonding might influence the melting points.

The complex structural chemistry of rare-earth quinolinates is explored in the study. Most synthetic methods to obtain rare-earth quinolinates yield a mixture of different species.