Fei-Yan Yi

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.

Synthesis, crystal structures, and luminescent properties of two series' of new lanthanide (III) amino-carboxylate-phosphonates.

Hydrothermal reactions of lanthanide(III) chlorides with 4-HOOC-C(6)H(4)-CH(2)NHCH(2)PO(3)H(2) (H(3)L) at different ligand-to-metal (L/M) ratios afforded nine new lanthanide(III) carboxylate-phosphonates with two types of 3D network structures, namely, LnCl(HL)(H(2)O)(2) (Ln = Sm, 1; Eu, 2; Gd, 3; Tb, 4; Dy, 5; Er, 6) and [Ln(2)(HL)(H(2)L)(L)(H(2)O)(2)].4H(2)O (Ln = Nd, 7; Sm, 8; Eu, 9). Compounds 1-6 are isostructural and feature a 3D network in which the LnO(7)Cl polyhedra are interconnected by bridging CPO(3) tetrahedra into 2D inorganic layers parallel to the bc plane. These layers are further cross-linked by organic groups of the carboxylate-phosphonate ligands via the coordination of the carboxylate groups into a pillared-layered architecture. Compounds 7-9 are also isostructural and feature a 3D open-framework composed of 1D lanthanide(III) phosphonate inorganic slabs which are further bridged by organic groups of the carboxylate-phosphonate liagnds via the coordination of the carboxylate groups, forming large 1D tunnels along the b-axis which are filled by lattice water molecules. Luminescent measurements indicate that compounds 2, 4, and 5 show strong emission bands in red, green, and yellow light region, respectively. Magnetic properties of 2, 3, 5, and 7 have also been studied.

An ultrastable porous metal–organic framework luminescent switch towards aromatic compounds

In this work, a highly stable MOF luminescent switch {Cd3(L)(bipy)2·4DMA}n (1) has been successfully constructed, which exhibits clear fluorescence enhancement and “turn-off” quenching responses for benzene and nitrobenzene vapors, respectively, with high selectivity and sensitivity, as well as being fully reusable. Remarkably, the porous MOF (1) remains intact in aqueous solution over an extensive pH range of 2–13. This MOF sensor realizes fast detection for benzene vapor with a response time of less than one minute and ∼8-fold fluorescence enhancement. Furthermore, it as a porous multifunctional MOF also shows fully reversible adsorption behaviour for benzene vapor at room temperature. Thus the MOF material will be a promising luminescent sensor and adsorbent material for benzene vapor with important practical applications from environmental and health points of view.

Syntheses and Crystal Structures of Novel Manganese(II) or Cadmium(II) Arsonates with Dinuclear Clusters or 1D Arrays

Hydrothermal reactions of cadmium(II) or manganese(II) salts with aryl arsenic acids RAsO(3)H(2) (R = C(6)H(5)-, H(2)L(1); 3-NO(2)-4-OH-C(6)H(3)-, H(3)L(2)) and 1,10-phenanthroline (phen) led to six new cadmium(II) and manganese(II) organo arsonates, namely, Cd(phen)(HL(1))(2)(H(2)O) (1), M(phen)(H(2)L(2))(2) (M = Mn, 2; Cd, 3), [M(phen)(2)(H(2)L(2))](ClO(4)) x (H(2)O) (M = Mn, 4; Cd, 5), and [Mn(phen)(2)(HL(1))](ClO(4)) x (H(2)O) (6). The structures of 1, 4, and 5 contain two types of dinuclear clusters, whereas 2 and 3 exhibit 1D chains based on dinuclear M(2)(mu-O)(2) cluster units further bridged by arsonate ligands. Compound 6 features a 1D helical chain in which neighboring two metal centers are bridged by one arsonate ligand. Magnetic property measurements on compounds 2, 4, and 6 indicate that there exist very weak antiferromagnetic interactions between magnetic centers in all three compounds. Compounds 1-6 display typical ligand-centered fluorescence emission bands.

Enhanced photocatalytic performance of BiOBr/NH2-MIL-125(Ti) composite for dye degradation under visible light.

Metal-organic frameworks (MOFs) are considered as suitable materials for various applications in the area of photocatalysis. On the other hand, 2D BiOBr materials are efficient for the photodegradation of organic dyes under visible light illumination. In this work, BiOBr/NH2-MIL-125(Ti) composite photocatalysts with different NH2-MIL-125(Ti) content were prepared by incorporating NH2-MIL-125(Ti) with BiOBr using a co-precipitation method. A series of characterizations confirmed the strong synergistic effect between BiOBr and NH2-MIL-125(Ti). In rhodamine B (RhB) degradation experiments, the composite photocatalyst with a mass percent of 7 wt% NH2-MIL-125(Ti) exhibited an improved photocatalytic activity compared to pristine BiOBr and NH2-MIL-125(Ti). Furthermore, the enhanced photocatalytic performance under visible light illumination could be attributed to the Ti3+-Ti4+ intervalence electron transfer and synergistic effect between NH2-MIL-125(Ti) and BiOBr, and also resulted in a separation efficiency of photo-generated electron-hole pairs during the photocatalytic reaction. This study can open up numerous opportunities for the development of various MOF-based visible light photocatalysts when combined with 2D bismuth oxyhalide materials for applications in environmental cleaning.

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 Nanoscale Multiresponsive Luminescent Sensor Based on a Terbium(III) Metal-Organic Framework.

A nanoscale terbium-containing metal-organic framework (nTbL), with a layer-like structure and [H2 NMe2 ](+) cations located in the framework channels, was synthesized under hydrothermal conditions. The structure of the as-prepared sample was systematically confirmed by powder XRD and elemental analysis; the morphology was characterized by field-emission SEM and TEM. The photoluminescence studies revealed that rod-like nTbL exhibited bright-green emission, corresponding to (5)D4 →(7)FJ (J=6-3) transitions of the Tb(3+) ion under excitation. Further sensing measurements revealed that as-prepared nTbL could be utilized as a multiresponsive luminescent sensor, which showed significant and exclusive detection ability for Fe(3+) ions and phenylmethanol. These results highlight the practical applications of lanthanide-containing metal-organic frameworks as fluorescent probes.

Construction of Cu(II) coordination polymers based on semi-rigid tetrahedral pyridine ligands

The assembly of a Cu(II) ion and the semi-rigid tetrahedral pyridine ligand, tetrakis(3-pyridyloxymethylene)methane (L1), yields three coordination polymers (1–3) by synergy between different solvent mixtures. Single crystal X-ray diffraction analyses reveal that Cu4(L1)(OAc)8 (1) features a two-dimensional sql network, and comprises dimeric five-coordinated Cu-centered square pyramids as the inorganic building units; Cu2(L1)(C7H5O2)4 (2) is also a layered assembly but with a 3,4-connected 3,4L13 net. In this complex, mononuclear CuO2N2 square planar structures and dinuclear CuO3N2 square pyramids both serve as the inorganic building units. Cu(H2O)2(L1)(OAc)2 (3) is a three-dimensional framework structure based on six-coordinated CuO2N4 square bipyramidal inorganic nodes and tetrahedral semi-rigid pyridine ligands, and dia topology is simplified for 3.

Towards rational design of zinc(II) and cadmium(II) sulfonate-arsonates with low dimensional aggregations

Hydrothermal reactions of zinc(II) or cadmium(II) salts with o-sulfophenylarsonic acid (o-HO3S-C6H4-AsO3H2, H3L) afforded two layered compounds, namely, [Zn2(L)(OH)(H2O)]·H2O (1) and [Cd3(L)2(H2O)3]·H2O (2). Introduction of 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), and 2,2′:6′,2′′-terpyridine (terpy) as auxiliary chelating ligands led to a series of zinc(II) or cadmium(II) sulfonate-arsonates with lower dimensional aggregations, namely, [Zn(HL)(bipy)2]2·6H2O (3), [Cd(HL)(bipy)]2 (4), [Zn(HL)(phen)]2·2H2O (5), [Cd(HL)(phen)(H2O)]2[Cd(HL)(phen)]2 (6), [Cd(HL)(phen)]2·2H2O (7), [Zn(HL)(terpy)]2 (8), [Cd(HL)(terpy)]2·2H2O (9), Zn(HL)(bipy) (10), Zn(HL)(bipy)·2H2O (11), and Zn(HL)(phen)·H2O (12). Compound 3 contains two mononuclear cluster units, whereas 4–9 feature five types of dinuclear cluster units in which a pair of Zn2+ or Cd2+ ions are interconnected by two sulfonate-arsonate ligands (via M–O–M, M–O–As–O–M and M–O–S–O–M bridges). Compounds 10 and 11 feature a one-dimensional (1D) chain in which each pair of Zn2+ centers are bridged by one arsonate group of a sulfonate-arsonate ligand. In compound 12, dinuclear clusters and 1D chains coexist. All twelve compounds display very strong fluorescence in the ultraviolet or blue light region.

Explorations of New Phases in the Ga-III/In-III-Cu-II-Se-IV-O System

Four new gallium(III)/indium(III), copper(II), selenium(IV) oxides, namely, Ga(2)Cu(SeO(3))(4) (1), Ga(2)CuO(SeO(3))(3) (2), and M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4), have been synthesized by hydrothermal or high-temperature solid-state reactions. The structure of Ga(2)Cu(SeO(3))(4) (1) features a 2D layer of corner-sharing GaO(6) and CuO(6) octahedra with the SeO(3) groups hanging on both sides of the 2D layer. Ga(2)CuO(SeO(3))(3) (2) features a pillared layered structure in which the 1D Cu(SeO(3))(3)(4-) chains act as the pillars between 2D layers formed by corner- and edge-sharing GaO(n) (n = 4, 5) polyhedra. Although the chemical compositions of M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4) are comparable, they belong to two different structural types. Ga(2)Cu(3)(SeO(3))(6) (3) exhibits a pillared layered structure built by [Ga(2)Cu(3)(SeO(3))(4)](4+) thick layers with Se(3)O(3)(2-) groups as pillars. The structure of In(2)Cu(3)(SeO(3))(6) (4) features a 3D network composed of [In(2)(SeO(3))(2)](2+) layers and [Cu(3)(SeO(3))(4)](2-) layers interconnected through Se-O-Cu and In-O-Cu bridges, exhibiting 8-MR helical tunnels along the a-axis. Results of magnetic property measurements indicate that there are considerable antiferromagnetic interactions between copper(II) centers in Ga(2)CuO(SeO(3))(3) (2) and M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4). Interestingly, Ga(2)Cu(3)(SeO(3))(6) (3) behaves as a weak ferromagnet below the critical temperature of T(c) = 15 K. Further magnetic studies indicate that the compound is a canted antiferromagnet with a large canting angle of about 7.1 degrees.