A bismuth-organic compound containing 2,2':6'2"-terpyridine (terpy) and 2-thiophenecarboxylate (TC), of the general formula (terpy)Bi(κ -TC) ⋅0.47 H O (BiOM-1), has been synthesized under hydrothermal conditions. Addition of a lanthanide nitrate solution to the reaction mixture led to statistical replacement of the bismuth centers, and yielded isomorphous lanthanide containing compounds Bi Ln OM-1 (Ln=Nd, Sm, Eu, Tb, Dy, Er, and Yb) that showed bismuth and/or ligand sensitized lanthanide-centered emission, and the first example of NIR emission from a lanthanide doped BiOM. The structure was determined by single-crystal X-ray diffraction, and the level and uniformity of lanthanide ion incorporation into the bismuth host was determined by ICP-OES and electron microprobe analysis. For the visible emitters, lifetime data and quantum yields are presented. A high efficiency of sensitization was calculated for the europium analog (50.1 %), showing significant improvement over previously reported europium thiophenecarboxylates. These novel materials may provide strategies to address concerns over the long-term sustainability of the rare earth elements, especially relating to optical devices.
A lanthanide series incorporating 2-thiophenecarboxylate and terpyridine is presented. Four structure types are observed with differences in the coordination number and nuclearity of the complexes attributed to the effects of the lanthanide contraction.
Two thorium(IV) compounds, [Th(H2O)4Cl4]·2(HPy·Cl) (1) and (HPy)3[Th3(H2O)2Cl10(OH)5]·4(HPy·Cl) (2) (HPy = pyridinium), were isolated from acidic aqueous solution.
The compounds were synthesized at room temperature and subsequently
characterized using single crystal X-ray diffraction along with Raman
and IR spectroscopies. Whereas compound 1 is built from
discrete mononuclear Th(H2O)4Cl4 units,
compound 2 consists of a novel hydroxo-bridged trimeric
[Th3(OH)5]7+ core. Such species are
largely absent from discussions of Th solution and solid-state chemistry
and their isolation may be attributed to outer coordination sphere
interactions that help stabilize the structural units; extensive hydrogen
bonding and π–π stacking interactions are present
in 1 and 2. Density functional theory calculations
were performed to predict the respective vibrational frequencies of
the structural units, and their relative stability was predicted at
the correlated molecular theory level. Small-angle X-ray scattering
analysis of [Th3(OH)5]7+ in water
indicates that the trimeric structural unit remains intact and that
it is indeed an important species that necessitates consideration
in geochemical models and for design of Th materials from water.
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