Weiting Yang

One-dimensional channel-structured Eu-MOF for sensing small organic molecules and Cu2+ ion

Two new lanthanide metal–organic frameworks Ln(FBPT)(H2O)(DMF) (FBPT = 2′-fluoro-biphenyl-3,4′,5-tricarboxylate, Ln = Eu and Tb) were prepared under solvothermal conditions. Single crystal X-ray diffraction analyses reveal that the two compounds are isostructurally related with the same one-dimensional channel structure on the basis of FBPT as an organic linker. Herein, the Eu(FBPT)(H2O)(DMF) (EuL) is selected as a representative sample for luminescent measurements. Study of the photoluminescence properties reveals that the EuL exhibits red emission, corresponding to the 5D0 → 7FJ (J = 1–4) transitions of the Eu3+ ion under UV light excitation. Most interestingly, when this compound was immersed in the different organic solvents and metal ion DMF solutions, it shows highly selective and sensitive sensing for small organic molecules and Cu2+ ions. In connection to this, a probable sensing mechanism was also discussed in this paper.

MOF-76: from a luminescent probe to highly efficient U(VI) sorption material.

MOF-76 exhibits not only high sensitivity for the detection of U(vi), but also high adsorption capacity of 298 mg g(-1) at a low pH value of ∼3.0. Furthermore, the high selectivity for uranium adsorption over a series of competing metal ions is also illustrated.

Facile and rapid fabrication of nanostructured lanthanide coordination polymers as selective luminescent probes in aqueous solution

Nanoscale Tb-active coordination polymers Tb(BTC)(H2O)6 were facilely, rapidly and environmentally-friendly fabricated at room temperature. The structures of the samples were confirmed by powder X-ray diffraction and elemental analyses, and the morphologies were characterized by SEM. The studies of the photoluminescence properties reveal that these nanostructured coordination polymers exhibit green emission, corresponding to the 5D4 → 7FJ transitions of the Tb3+ ions under UV light excitation, which represents highly selective and sensitive sensing for metal ions and acetone molecules in aqueous solution, and the probable sensing mechanisms were discussed.

Highly selective acetone fluorescent sensors based on microporous Cd(II) metal–organic frameworks

Solvothermal reaction of Cd2+ ions and a hexavalent carboxylic acid (H6666666L) afforded a Cd(II) metal organic framework (Cd-MOF), namely {[Cd3(L)(H2O)2(DMF)2]·5DMF}n (1). Its structure consists of trinuclear CdII building units, which are further bridged by the carboxylic ligand, resulting in a 4,4-connected topological net (sra). By introducing a rigid N-donor ligand 1,4-bis(1-imidazolyl)benzene (dib), a new Cd-MOF (2) {[Cd3(L)(dib)]·3H2O·5DMA}n was isolated, in which the coordinated sites of solvent molecules in 1 were completely replaced by dib. The resulting trinuclear Cd3 subunits are further bridged into a two-fold interpenetrating network with DMA and water molecules located in the void space. The luminescent properties of the two microporous Cd-MOFs dispersed in different solvents have been investigated systematically, demonstrating unique selectivity for the detection of acetone via a fluorescence quenching mechanism. Their luminescence intensities decreased to 50% at an acetone content of 0.3 vol% and were almost completely quenched at a concentration of 1.0 vol%, thus, they can be considered as excellent potential luminescent probes for the detection of acetone.

3-Fold-Interpenetrated Uranium–Organic Frameworks: New Strategy for Rationally Constructing Three-Dimensional Uranyl Organic Materials

The first series of 3-fold-interpenetrated uranium-organic frameworks, UOF-1 and UOF-2, have been synthesized by hydrothermal reactions of flexible semirigid carboxylic acids and uranyl nitrate. Structure analyses indicate that UOF-1 and UOF-2 possess flu and pts topologies, respectively.

Syntheses and structures of a series of uranyl phosphonates and sulfonates: an insight into their correlations and discrepancies.

Six uranyl phosphonates and sulfonates have been hydrothermally synthesized, namely, (H2tib)[(UO2)3(PO3C6H5)4]·2H2O (UPhP-1), Zn(pi)2(UO2)(PO3C6H5)2 (UPhP-2), Zn(dib)(UO2)(PO3C6H5)2·2H2O (UPhP-3), (HTEA)[(UO2)(5-SP)] (USP-1), (Hdib)2[(UO2)2(OH)(O)(5-SP)] (USP-2), and Zn(phen)3(UO2)2(3-SP)2 (USP-3) (tib = 1,3,5-tri(1H-imidazol-1-yl)benzene, pi = 1-phenyl-1H-imidazole, dib = 1,4-di(1H-imidazol-1-yl)benzene, TEA = triethylamine, phen = 1,10-phenanthroline, 5-SP = 5-sulfoisophthalic acid, and 3-SP = 3-sulfoisophthalic acid). UPhP-1 has been determined to be a layered structure constructed by UO7 pentagonal bipyramids, UO6 octahedra, and phenylphosphonates. Protonated tib plays a role in balancing the negative charge and holding its structure together. UPhP-2 is made up of UO6 octahedra, ZnO2N2 tetrahedra and PO3C tetrahedra in phenylphosphonates, forming a 1D assembly, which is stabilized by chelate phen ligand. Further connection of such chainlike structure via dib yields a 2D layered architecture of UPhP-3. Although sulfonate group possesses similar tetrahedral structure as the phosphonate group, a unidentated coordination mode is only found in this work. UO7 pentagonal bipyramids are linked by 5-SP to form the layered assembly of USP-1. USP-2 also consists of the same sulfonate ligand, but features tetranulear uranyl clusters. Similarly, protonated TEA and dib molecules enable stabilization of their structures, respectively. Formed by dinuclear uranyl cluster and 3-SP ligand, USP-3 appears as a 1D arrangement, in which Zn(phen)3 acts as the counterion to compensate the negative charge. All of these compounds have been characterized by IR and photoluminescent spectroscopy. Their characteristic emissions have been attributed as transition properties of uranyl cations.

Flexible Diphosphonic Acids for the Isolation of Uranyl Hybrids with Heterometallic U-VI=O-Zn-II Cation-Cation Interactions

A family of uranyl diphosphonates have been hydrothermally synthesized using various flexible diphosphonic acids and Zn(UO2)(OAc)4·7H2O in the presence of bipy or phen. Single-crystal X-ray analyses indicate that these compounds represent the first examples of uranyl phosphonates with heterometallic U(VI)═O-Zn(II) cation-cation interactions.

Construction of porous Mn(II)-based metal-organic frameworks by flexible hexacarboxylic acid and rigid coligands

Solvothermal reactions of hexa[4-(carboxyphenyl)oxamethyl]-3-oxapentane (H6L) with rigid coligands, 2,2′-bipyridine (bipy), 1,4-bis-(1-imidazolyl)benzene (dib), and 4,4′-bis(1-imidazolyl)biphenyl (bibp) in the presence of manganese salts produce four porous Mn(II) metal–organic frameworks (Mn–MOFs), namely, Mn3(L)(bipy)2 (1), Mn3(L)(dib) (2), Mn3(L)(dib)(H2O)2 (3), and Mn6(L)2(bibp)1.5(H2O)54. Single crystal X-ray diffraction analyses reveal that 1–4 consist of trinuclear MnII subunits, which are further connected into four interesting nets, 4,4-connected pts net for 1, 4,6-connected fsc net for 2, and two novel nets for 3 and 4, by the synergistic effect of carboxylate groups and functionally complementary N-donor ligands. They exhibit high potential solvent accessible volumes of 35.0%, 33.5%, 45.1%, and 56.5% for 1–4, respectively. Magnetic studies indicate the presence of weak antiferromagnetic interactions between MnII centers in these compounds.

A nanosized {Ag@Ag12} "molecular windmill" templated by polyoxometalates anions.

Reaction of multidentate 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole (L) ligand with Ag(I) ions in the existence of H3PW12O40 as anionic template under hydrothermal conditions results in tridecanuclear silver cluster-polyoxometalates hybrid: {Ag13L12}{PW12O40}4·30H2O (1). X-ray single crystal diffraction analysis indicates that the main structural feature of 1 is a nanosized molecular windmill-shaped polynuclear Ag cluster with intriguing {M@M12}-type cuboctahedral topology. The as-synthesized compound exhibits effective photocatalytic activity in the photodegradation of Rhodamine-B (RhB) and antibacterial activity against Escherichia coli, respectively.

Photochromic Terbium Phosphonates with Photomodulated Luminescence and Metal Ion Sensitive Detection.

Rational selection and modification of rare earth metal centers and photoactive organic linkers enables designable multiphotofunctionality to come to fruition in new hybrid coordination polymer materials. By using a viologen-functionalized diphosphonate linker, two terbium phosphonate compounds (Tb-1 and Tb-2) have been constructed, which display reversible photochromic reactions in response to UV light and soft X-ray irradiation. In addition, the photo-induced electron-transfer reaction can modulate the luminescent emission to thus realize photoluminescence switching behavior. Furthermore, both terbium phosphonates can serve as highly sensitive sensors to probe Cu2+ in solution through their luminescence. Thus, they represent the first photochromic examples of lanthanide phosphonate-based materials with photomodulated luminescence and sensitive detection of metal ions.