Search

Under the hydrothermal condition and presence of organic amines, incorporating lanthanide (Ln) ions into monolacunary Keggin‐type germanotungstate precursor resulted in the formation of two new complex clusters formulated as H17(H2en)5[K3(H2O)(GeW10O37TbOTb)4(μ6‐W3O12)] ⋅ 45H2O (GeW‐Tb) and H22(H2en)3[K2(GeW10O37EuOEu)4(H2O)(μ6‐W3O12)] ⋅ 44H2O (GeW‐Eu) (en=ethylenediamine), which have been structurally characterized by elemental analyses, ICP analysis, IR spectra, thermogravimetric analysis, bond valence sum calculations and single‐crystal X‐ray diffraction. The most prominent structural feature of GeW‐Eu and GeW‐Tb revealed an unprecedented oxygen‐bridging Ln‐substituted bilacunary Keggin‐type germanotungstate tetramers encapsulating [W3O12]6− connector. What's more interesting is that a versatile library of linkable units including bilacunary germanotungstate [α‐GeW10O37]10−, internal oxo group between two Ln ions, as well as central tritungstate intermediate [W3O12]6− are all generated in situ thanks to the potential promotion of hydrothermal reaction system. In particular, the possible assembly mechanism for the complex clusters is proposed, and their solid‐state photoluminescence properties are also discussed in detail. To our knowledge, both [α‐GeW10O37]10− and [W3O12]6− intermediates are the highly robust POM building blocks that were first discovered. The studies highlight the structural diversity of Ln‐substituted germanotungstates and provide a new direction in the design of other functional germanotungstate based POMs in the future. [ABSTRACT FROM AUTHOR]

Based on DMF solvent, four titanium-oxo clusters (TOCs) [Ti10(μ3-O)12(L)6(OiPr)10(DMF)2] (Ti–L) (L = 4-methylbenzoate (MB), 3,5-di-tert-butylbenzoate (DTBB), 4-methoxybenzoate (MOB) and 4-methyl-3,5-dinitrobenzoate (MDNB)) with the same coordination environments have been solvothermally synthesized with high yield between benzoic acid derivatives and Ti(OiPr)4. Single crystal X-ray diffraction analysis confirmed that Ti–L presents an open cage-like structure made up of a substituted benzoate-anchored decanuclear titanium-oxo cluster featuring an unprecedented defective double-cubane geometry. The photophysical performance of Ti–L demonstrated that strong electron-withdrawing substituent groups on the benzoate skeleton are beneficial to the redshift of the absorption position and the decrease of the band gap for the TOCs. Due to the synergistic effects of its lowest band gap and open cage-like structure, Ti–MOB exhibited effective photocatalytic degradation of rhodamine B. [ABSTRACT FROM AUTHOR]

A novel organic–inorganic hybrid, cadmium(II)-magnesium(II)-molybdenum(V) phosphate, {Cd[(PO4)2(HPO4)2Mo6O11(OH)4]2}[Cd(H2O)]2[Mg(Hen)]2{Cd[(PO4)3(HPO4)Mo6O10(OH)3Cl2]2}·(H2en)4·(Hen)2·(en)2·9H2O (en = ethylenediamine), was prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, inductively coupled plasma (ICP) analysis, thermogravimetric analysis, fluorescence, FT-IR and bond valence sum calculations. As revealed by single-crystal X-ray diffraction studies, the sandwich-shaped clusters of [Cd(Mo6P4)2] are interconnected by additional [Mg(Hen)] units and [Cd(H2O)] fragments to form an extended three-dimensional supramolecular framework with channels occupied by ethylenediamine molecules, protonated ethylenediamine cations and water molecules. Luminescent measurement of the title compound exhibits intensive blue and greenish-blue radiation emission upon excitation with ultraviolet light. [ABSTRACT FROM AUTHOR]

A new inorganic–organic hybrid material (C10H8N2H)2(Mo8O26) · 2NH4 ( 1) was prepared under solvothermal conditions (H2O/ethanol), which was then used as a starting material in the synthesis of another material, (C10H8N2Cu)2(Mo8O26) · 2NH4 ( 2). Each compound has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, thermogravimetric analysis, fluorescence, FT-IR, and bond valence sum calculations. The comparative study focuses on the transformation and structural change between 1 and 2, which arises from the simple substitution of the proton in 1 with the Cu+ ions. The other surprising feature is that Cu+ ions can not only directly be used to substitute the proton of 1 but also ameliorate its photoluminescence property. It means that 1 appears to have recognizable functional protons in the solid-state structure and, hence, can very well be considered as an ideal precursor agent to design the functional materials with special architectures and photoactive properties. [ABSTRACT FROM AUTHOR]

New anhydrous lanthanide metal-organic frameworks (MOFs) [Pr(tip)1.5]2n (tip-Pr), [Nd(tip)1.5]2n (tip-Nd), [Eu-(tip)1.5]2n (tip-Eu), and [Eu(OH)(mip)]n (mip-Eu) (tip=5-tert-butylisophthalate anion, mip=5-methylisophthalate ion), have been hydrothermally synthesized and structurally characterized by elemental analyses, FT-IR spectroscopy, single-crystal X-ray diffraction, thermal gravimetric analysis/differential thermal analysis (TG/DTA), and X-ray powder diffraction (XRPD) techniques. MOFs tip-Pr, tip-Nd, and tip-Eu are isostructural anhydrous compounds, and exhibit an unprecedented 3D microporous structure with hexagonal channel arrays. The selectively prepared MOF mip-Eu presents an interpenetrated 3D microporous architecture containing the hydroxyl cluster chains. Solid-state photoluminescence properties at room temperature indicate that both tip-Eu and mip-Eu display the characteristic of the Eu3+ ion spectrum dominated by the 5D0-->7F(J) (J=0-4) transition. Compared with mip-Eu, tip-Eu displays the very high solid-state quantum yield (0.62 ± 0.03) and longer lifetime value (0.94 ± 0.01 ms), which is due to the absence of the hydroxyl groups from the solid-state structure of tip-Eu. More importantly, a new method to directly investigate the potential of solid-state lanthanide MOFs for ionic sensing in aqueous solutions has been developed, and successfully applied it to study the potential sensing function of tip-Eu for polyoxometalates (POMs). The possible mechanism for the quenching effect of POMs on the fluorescence of tip-Eu is elucidated by the strongly competitive absorption of the excited light source energy between POMs and tip ligands. The very promise for the highly sensitive sensing for polyoxometalates, together with the characteristic of the reversible fluorescence response, suggest that solid-state tip-Eu can be an excellent candidate for the directly photoluminescent detection of POMs in aqueous solutions.

The hydrothermal reaction of rare earth oxide, CuO, 2,6-pyridinedicarboxylic acid, and 4,4'-bipyridine in the presence of H(3)PO(3) resulted in the formation of a new series of 3d-4f heterometallic coordination polymers [Ln(pydc)(3)Cu(3)(bipy)(3).m(H(2)O)](n) (Ln = Pr (1), Nd (2), m = 5; Ln = Sm (3), Eu (4), Gd (5), Tb (6), Er (7), Yb (8), m = 4; pydc = 2,6-pyridinedicarboxylate anion; bipy = 4,4'-bipyridine). Complexes 1-8 are isostructural and structurally characterized by elemental analysis, FT-IR spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA), single-crystal X-ray diffraction, X-ray powder diffraction (XRPD), and nitrogen adsorption/desorption techniques. The synthesis results show that the addition of H(3)PO(3) in the reaction plays an important role in the formation of the compounds. Single-crystal X-ray diffraction analysis reveals that the heterometallic ions are first interconnected by mixing bridging ligands to produce a spindle-shaped heterometallic ring [Ln(6)(pydc)(6)Cu(12)(bipy)(6)], which is used as the second building unit (SBUs) and finally pillared by bridging bipy molecules to form the rare 3D pillared-layer porous Ln(III)-Cu(I) coordination polymers. Luminescence measurements made under excitation by UV rays reveal that Sm-Cu, Eu-Cu, and Tb-Cu compounds exhibit the characteristic emission bands of Sm(3+), Eu(3+), and Tb(3+) ions in the visible regions, respectively; near-infrared (NIR) emission bands from Nd(III) and Yb(III) ions can also be obtained in Nd-Cu and Yb-Cu compounds, respectively; while Pr-Cu, Gd-Cu, and Er-Cu compounds all display similar emission spectra of Cu(I) coordination compounds in the visible regions.