Diverse Lanthanide Coordination Polymers with 3,3'-Dimethylcyclopropane-1,2-dicarboxylate Ligand: Synthesis, Crystal Structure, and Properties.

In an attempt to investigate the influence of many variables on the synthesis of lanthanide coordination polymers (Ln-CPs) assembled from the ligand 3,3-dimethylcyclopropane-1,2-dicarboxylic acid, three different Ln-CPs with formulae [La9(µ4-dcd)12(µ3-O)2(H)] n (1), [Gd4(µ4-dcd)6(H2O)] n (2), and [Gd2(µ3-OH)2(µ3-dcd)(µ2-ac)2(H2O)] n (3) (dcd = 3,3-dimethylcyclopropane-1,2-dicarboxylate, ac = acetate) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, thermal analysis, powder X-ray diffraction, and single X-ray diffraction techniques. 1 represents the first report of the three-dimensional (3D) Ln-CPs based on nonanuclear lanthanide clusters, although it shows extremely low gas uptakes. 2 exhibits one of the previously reported 3D lanthanide wheel cluster-like frameworks. 3 characterizes a novel one-dimensional ladder-like chain [Gd4(OH)4] n decorated with mixed ligand ribbons. Variable-temperature magnetic susceptibility measurement reveals that the shortest Gd···Gd distance in 3 induces the antiferromagnetic interactions between adjacent Gd3+ cations within the hydroxyl-bridged binuclear unit. Remarkably, magnetic investigation for 2 indicates a unique metamagnetic transition from the antiferromagnet to ferromagnet. Furthermore, magnetic studies for 2 also exhibit the presence of significant magnetocaloric effect with a large magnetic entropy change.

Highly Water-Stable Novel Lanthanide Wheel Cluster Organic Frameworks Featuring Coexistence of Hydrophilic Cagelike Chambers and Hydrophobic Nanosized Channels.

In attempts to investigate the potential luminescent sensing materials for sensitive detection of environmental pollutants, a new family of lanthanide wheel cluster organic frameworks (Ln-WCOFs) UJN-Ln4 has been constructed by employing one of the cycloalkane dicarboxylic acid derivatives. Adopting different conformations, the ligand links Ln4 second building units (SBUs) and Ln24 tertiary building units (TBUs) to form a unique wheel cluster layer-pillared 3D framework featuring the coexistence of hydrophobic nanosized channels and trigonal antiprism arrays with hydrophilic cagelike chambers. Apart from charming structures, isostructural UJN-Ln4 displays interesting porous, water-stable features. Systematic luminescence studies demonstrate that solvent water molecules can enhance the emission intensity of solid-state UJN-Eu4. Acting as a recyclable luminescent probe, water-stable luminescent UJN-Eu4 exhibits superior "turn-off" detection for Fe3+ and Cu2+ ions in aqueous solutions. Due to the nanosized hydrophobic channels, UJN-Eu4 also shows highly sensitive sensing of sodium dodecyl benzenesulfonate (SDBS) via luminescence "turn-on" respondence, representing the first example of quantitatively detecting SDBS in aqueous solutions by employing luminescent lanthanide frameworks as fluorescent sensors. The results also open up the exploration of novel luminescent Ln-WCOFs exhibiting unique applications in sensitive detecting of harmful pollutants in aquatic environments.

New Family of Octagonal-Prismatic Lanthanide Coordination Cages Assembled from Unique Ln17 Clusters and Simple Cliplike Dicarboxylate Ligands.

Novel high-nuclearity lanthanide clusters (Ln17) are generated in situ in the coordination-driven self-assembly. A metal-cluster-directed symmetry strategy for building metal coordination cages is successfully applied to a lanthanide system for the first time. A new family of octagonal-prismatic lanthanide coordination cages UJN-Ln, formulated as [Ln(µ3-OH)8][Ln16(µ4-O)(µ4-OH)(µ3-OH)8(H2O)8(µ4-dcd)8][(µ3-dcd)8]·22H2O (Ln = Gd, Tb, Dy, Ho, and Er; dcd = 3,3-dimethylcyclopropane-1,2-dicarboxylate dianion), have been assembled from the unique Ln17 clusters and simple cliplike ligand H2dcd. Apart from featuring aesthetically charming structures, all of the compounds present predominantly antiferromagnetic coupling between the corresponding lanthanide ions. Additionally, the intense-green photoluminescence for UJN-Tb and magnetic relaxation behavior for UJN-Dy have been observed. Remarkably, UJN-Gd shows a large magnetocaloric effect (MCE) with an impressive entropy change value of 42.3 J kg(-1) K(-1) for ΔH = 7.0 T at 2.0 K due to the high-nuclearity cluster and the lightweight ligand. The studies highlight the structural diversity of multigonal-prismatic metal coordination cages and provide a new direction in the design of cagelike multifunctional materials by the introduction of lanthanide clusters and other suitable cliplike ligands.

Anhydrous lanthanide MOFs and direct photoluminescent sensing for polyoxometalates in aqueous solution.

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.

Structure and photoluminescence tuning features of Mn(2+)- and Ln(3+)-activated Zn-based heterometal-organic frameworks (MOFs) with a single 5-methylisophthalic acid ligand.

In attempts to investigate whether the photoluminescence properties of the Zn-based heterometal-organic frameworks (MOFs) could be tuned by doping different Ln(3+) (Ln = Sm, Eu, Tb) and Mn(2+) ions, seven novel 3D homo- and hetero-MOFs with a rich variety of network topologies, namely, [Zn(mip)](n) (Zn-Zn), [Zn(2)Mn(OH)(2)(mip)(2)](n) (Zn-Mn), [Mn(2)Mn(OH)(2)(mip)(2)](n) (Mn-Mn), [ZnSm(OH)(mip)(2)](n) (Zn-Sm), [ZnEu(OH)(mip)(2)](n) (Zn-Eu1), [Zn(5)Eu(OH)(H(2)O)(3)(mip)(6)·(H(2)O)](n) (Zn-Eu2), and [Zn(5)Tb(OH)(H(2)O)(3)(mip)(6)](n) (Zn-Tb), (mip = 5-methylisophthalate dianion), have been synthesized hydrothermally based on a single 5-methylisophthalic acid ligand. All compounds are fully structurally characterized by elemental analysis, FT-IR spectroscopy, TG-DTA analysis, single-crystal X-ray diffraction, and X-ray powder diffraction (XRPD) techniques. The various connectivity modes of the mip linkers generate four types of different structures. Type I (Zn-Zn) is a 3D homo-MOF with helical channels composed of Zn(2)(COO)(4) SBUs (second building units). Type II (Zn-Mn and Mn-Mn) displays a nest-like 3D homo- or hetero-MOF featuring window-shaped helical channels composed of Zn(4)Mn(2)(OH)(4)(COO)(8) or Mn(4)Mn(2)(OH)(4)(COO)(8) SBUs. Type III (Zn-Sm and Zn-Eu1) presents a complicated corbeil-like 3D hetero-MOF with irregular helical channels composed of (SmZnO)(2)(COO)(8) or (EuZnO)(2)(COO)(8) heterometallic SBUs. Type IV (Zn-Eu2 and Zn-Tb) contains a heterometallic SBU Zn(5)Eu(OH)(COO)(12) or Zn(5)Tb(OH)(COO)(12), which results in a 3D hetero-MOF featuring irregular channels impregnated by parts of the free and coordinated water molecules. Photoluminescence properties indicate that all of the compounds exhibit photoluminescence in the solid state at room temperature. Compared with a broad emission band at ca. 475 nm (λ(ex) = 380 nm) for Zn-Zn, compound Zn-Mn exhibits a remarkably intense emission band centered at 737 nm (λ(ex) = 320 nm) due to the characteristic emission of Mn(2+). In addition, the fluorescence intensity of compound Zn-Mn is stronger than that of Mn-Mn as a result of Zn(2+) behaving as an activator for the Mn(2+) emission. Compound Zn-Sm displays a typical Sm(3+) emission spectrum, and the peak at 596 nm is the strongest one (λ(ex) = 310 nm). Both Zn-Eu1 and Zn-Eu2 give the characteristic emission transitions of the Eu(3+) ions (λ(ex) = 310 nm). Thanks to the ambient different crystal-field strengths, crystal field symmetries, and coordinated bonds of the Eu(3+) ions in compounds Zn-Eu1 and Zn-Eu2, the spectrum of the former compound is dominated by the (5)D(0) → (7)F(2) transition (612 nm), while the emission of the (5)D(0) → (7)F(4) transition (699 nm) for the latter one is the most intense. Compound Zn-Tb emits the characteristic Tb(3+) ion spectrum dominated by the (5)D(4) → (7)F(5) (544 nm) transition. Upon addition of the different activated ions, the luminescence lifetimes of the compounds are also changed from the nanosecond (Zn-Zn) to the microsecond (Zn-Mn, Mn-Mn, and Zn-Sm) and millisecond (Zn-Eu1, Zn-Eu2, and Zn-Tb) magnitude orders. The structure and photoluminescent property correlations suggest that the presence of Mn(2+) and Ln(3+) ions can activate the Zn-based hetero-MOFs to emit the tunable photoluminescence.

Novel three-dimensional pillared-layer Ln(III)-Cu(I) coordination polymers featuring spindle-shaped heterometallic building units.

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.

Effects of calcination temperature on the pore size and wall crystalline structure of mesoporous alumina.

In this paper, mesoporous alumina with different pore sizes and wall crystalline structures was synthesized at calcination temperatures over 550 degrees C. The characterization of the samples calcined at 550, 800, 1100, and 1300 degrees C, respectively, was performed using TEM, XRD, FTIR, TG/DTA, and N2 adsorption/desorption techniques. The correlation between pore size and wall crystalline structure on calcination temperature was systematically investigated.