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Herein, we report on the preparation of liquid dimeric lanthanide(III)‐containing compounds. Starting from the design of dimeric solids, we demonstrate that by tuning of anion and cation structures we can lower the melting points below room temperature, whilst maintaining the dimeric structure. Magnetic measurements could establish the spin‐spin interactions of the neighboring lanthanide(III) ions in the liquid state at low temperatures, and matched the interactions of the analogous crystalline solid compounds. [ABSTRACT FROM AUTHOR]

Abstract: The near-infrared luminescence properties of three (E)-N-hexadecyl-N′,N′-dimethylamino-stilbazolium tetrakis(1-phenyl-3-methyl-4-benzoyl-5-pyrazolonato) lanthanide(III) complexes are described. These three complexes, containing trivalent neodymium, erbium and ytterbium, respectively, show near-infrared luminescence in acetonitrile solution upon UV irradiation. Luminescence decay times have been measured. The complexes consist of a positively charged hemicyanine chromophore with a long alkyl chain and a tetrakis(pyrazolonato) lanthanide(III) anion. Because of the absence of an α-hydrogen atom in the pyrazolonato ligands, and because of the saturation of the coordination sphere by four bidentate ligands, the luminescence properties are enhanced when compared to, e.g. quinolinate complexes. [Copyright &y& Elsevier]

It is shown that ionic liquids are promising solvents for near-infrared emitting lanthanide complexes, because ionic liquids are polar non-coordinating solvents that can solubilize lanthanide complexes. Neodymium(III) tosylate, bromide, triflate and sulfonylimide complexes were dissolved in 1-alkyl-3-methylimidazolium ionic liquids that contain the same anion as the neodymium(III) complexes. Near-infrared luminescence spectra of these neodymium(III) salts were measured by direct excitation of the neodymium(III) ion. The absorption spectra show detailed crystal-field fine structure and Judd–Ofelt parameters have been determined. Intense near-infrared luminescence was observed upon ligand excitation for neodymium(III) complexes with 1,10-phenanthroline or β-diketonate ligands. [Copyright &y& Elsevier]

The article reports on the synthesis of the first ionic liquids containing lanthanide that were based on the 1-butyl-3-methylimidazolium cation and lanthanide thiocyanate anions. A metathesis procedure starting from stoichiometric amounts of lanthanide(III) perchlorate, ammonium thiocyanate, and a thiocyanate ionic liquid was used to synthesize the compounds. It claims that most of these liquids are supercooled at room temperature and likewise tend to form glasses upon cooling.

Near-infrared-emitting rare-earth chelates based on 8-hydroxyquinoline have appeared frequently in recent literature, because they are promising candidates for active components in near-infrared-luminescent optical devices, such as optical amplifiers, organic light-emitting diodes …. Unfortunately, the absence of a full structural investigation of these rare-earth quinolinates is hampering the further development of rare-earth quinolinate based materials, because the luminescence output cannot be related to the structural properties. After an elaborate structural elucidation of the rare-earth quinolinate chemistry we can conclude that basically three types of structures can be formed, depending on the reaction conditions: tris complexes, corresponding to a 1:3 metal-to-ligand ratio, tetrakis complexes, corresponding to a 1:4 metal-to-ligand ratio, and trimeric complexes, with a 3:8 metal-to-ligand ratio. The intensity of the emitted near-infrared luminescence of the erbium(Ill) complexes is highest for the tetrakis complexes of the dihalogenated 8-hydroxyquinolinates. [ABSTRACT FROM AUTHOR]

Near-infrared emitting complexes of Nd(Ill), Er(Ill), and Yb(lll) based on hexacoordinate lanthanide ions with an aryl functionalized imidodiphosphinate ligand, tpip, have been synthesized and fully characterized. Three tpip ligands form a shell around the lanthanide with the ligand coordinating via the two oxygens leading to neutral complexes, Ln(tpip)3. In the X-ray crystal structures of Er(III) and Nd(Ill) complexes there is evidence of CH-π interactions between the phenyl groups. Photophysical investigations of solution samples of the complexes demonstrate that all complexes exhibit relatively long luminescence lifetimes in nondeuteurated solvents. Luminescence studies of powder samples have also been recorded for examination of the properties of NIR complexes in the solid state for potential material applications. The results underline 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, both features important in the design of NIR emitting lanthanide complexes. [ABSTRACT FROM AUTHOR]

A range of liquid rare earth chlorometallate complexes with the alkyl-phosphonium cation, [P666 14]+, has been synthesized and characterized. EXAFS confirmed the predominant liquid-state speciation of the [LnCl6]3- ion in the series with Ln = Nd, Eu, Dy. The crystal structure of the shorter-alkyl-chain cation analogue [P4444]+ has been determined and exhibits a very large unit cell. The luminescence properties, with visible-light emissions of the liquid Tb, Eu, Pr, and Sm and the NIR emissions for the Nd and Er compounds, were determined. The effective magnetic moments were measured and fitted for the Nd, Tb, Ho, Dy, Gd, and Er samples. [ABSTRACT FROM AUTHOR]

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline (Fc2phen) and ferrocenoyltrifluoroacetone (Hfta) have been used to synthesize ferrocene-containing rare-earth β-diketonate complexes. The complexes [Ln(tta)3-(Fc2phen)] and [Ln(fta)3(phen)] (where Ln = La, Nd, Eu, Yb) show structural similarities to the tris(2-thenoyltrifluoroacetonate)(1,10-phenanthroline)lanthanide(III) complexes, [Ln(tta)3(phen)]. The coordination number of the lanthanide ion is 8, and the coordination sphere can be described as a distorted dodecahedron. However, the presence of the ferrocene moieties shifts the ligand absorption bands of the rare-earth complexes to longer wavelengths so that the complexes can be excited not only by ultraviolet radiation but also by visible light of wavelengths up to 420 nm. Red photoluminescence is observed for the europium(lll) complexes and near-infrared photoluminescence for the neodymium(III) and ytterbium(III) complexes. The presence of the ferrocene groups makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents. [ABSTRACT FROM AUTHOR]

Abstract: Purposely designed ionic liquids can be excellent solvents for spectroscopic studies of rare earth compounds. Absorption, excitation and emission spectra of LnI3 (Ln=Nd, Dy and Tb) in the ionic liquid 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide are presented. Electronic transitions were assigned from the energy level diagrams for Ln(III). Emission lifetimes for DyI3 in [C12mim][Tf2N] are discussed. Traces of water dramatically reduce the otherwise long lifetimes and comparatively high quantum yields. [Copyright &y& Elsevier]

Abstract: The solubility and uniform distribution of lanthanide complexes in sol–gel glasses can be improved by covalently linking the complexes to the sol–gel matrix. In this study, several lanthanide -diketonate complexes (Ln=Nd, Sm, Eu, Tb, Er, Yb) were immobilized on a 1,10-phenanthroline functionalized sol–gel glass. For the europium(III) complex, a sol–gel material of diethoxydimethylsilane (DEDMS) with polymer-like properties was derived. For the other lanthanide complexes, the sol–gel glass was prepared by using a matrix of tetramethoxysilane (TMOS) and DEDMS. Both systems were prepared under neutral reaction conditions. High-resolution emission and excitation spectra were recorded. The luminescence lifetimes were measured. [Copyright &y& Elsevier]