Jing-Xin Meng

Controllable self-assembly of four new metal–organic frameworks based on different phosphomolybdate clusters by altering the molar ratio of H3PO4 and Na2MoO4

By adjusting the molar ratio of the reactants H3PO4 and Na2MoO4, four new metal–organic frameworks, namely, CoH(bix)4[PMoVI8VV4O40(VIVO)2] (1), (H2bix)2(NaHP2Mo5O23)·2H2O (2), H2(bix)4[Cd(H2O)4][Cd(HPO4)4(H2PO4)4(MoO2)12 (OH)6]·10H2O (3) and (H2en)3(Co3P4Mo4O28) (4) (bix = 1,4-bis(imidazol-1-ylmethyl)benzene, en = 1,2-ethylenediamine), have been hydrothermally prepared and characterized by elemental analyses, IR spectroscopy, TG analyses, and single-crystal X-ray diffraction. Compound 1 consists of straight chains based on pseudo-Keggin [PMoVI8VV4O40(VIVO)2]3−polyanions and [CoH(bix)4]3+ complex fragments, which are further connected into a three-dimensional (3D) open framework by hydrogen bonding interactions between polyanions and organic bix ligands . Compound 2 shows 3D supramolecular networks constructed from weak interactions between free biprotonated bix, water and oxygen atoms of polyanions [P2Mo5O23]6−. In compound 3, [Cd(HPO4)4(H2PO4)4(MoO2)12(OH)6]4−polyanions are linked by [Cd(H2O)4]2+ cations to build one-dimensional (1D) chains. Then weak interactions between free bix ligands, water and oxygen atoms of the polyanions extend these 1D chains to 3D supramolecular frameworks. Compound 4 exhibits open-framework structures. Interestingly, it also shows 1D left and right-handed helical chains and 2D (6,3)-layers. The molar ratio of the reactants H3PO4 and Na2MoO4 influence the transformation of the phosphomolybdate clusters in compounds 1–4. The electrochemistry and photocatalysis properties of these compounds have also been investigated in this paper.

Controllable self-assembly of two novel metal–organic frameworks based on different tetradentate in situ ligands

Two novel metal–organic frameworks (MOFs) based on different tetradentate in situ ligands, CuI3(L1)2(L2)[PMoVI8VV4O40(VIVO)2]·2H2O (1) and [CuI2Cl2(L3)] (2) (L1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L2 = 1,2,4,5-tetra(4-pyridyl)-benzene L3 = a-1-hydroxy-e,e,e,e-1,2,4,5-tetra(4-pyridyl)cyclohexane) have been rationally hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, TG analyses, and single-crystal X-ray diffraction, respectively. Here, compound 1 represents the first example that dehydrogenative coupling has been employed to yield a novel tetradentate coplanar dye molecule in POM-based MOFs. It also exhibits unique 3D MOFs with two topologies (4284)(4283101)(86)2 and (4383)(4284)(446289)(4106183) due to different definitions of nodes. Compound 2 shows a two-fold diagonal/diagonal inclined interpenetration based on CuI ions and in situ synthesized ligands L3. Interestingly, reaction conditions play important roles in the domination of in situ ligands (L2 and L3) from the same precursor bpp (bpp = 1,3-bis(4-pyridyl)propane). Additionally, electrochemical and photocatalysis properties of compound 1 have also been minutely investigated.

Syntheses and crystal structures of two compounds based on saturated keggin-type polyoxotungstates and mixed ligands

Two new polyoxotungstates with dafo and 4,4′-bipy ligands, [Ag(dafo)2]2{[Ag(4,4′-bipy)]2SiW12O40} (1) and [Cd2(dafo)4(4, 4′-bipy)(H2O)2](dafo) SiW12O40 (2) (dafo = 4, 5-diazafluoren-9-one, 4,4′-bipy = 4,4′-bipyridine), have been hydrothermally synthesized and characterized by elemental analyses, IR, TG and single crystal X-ray diffraction. Compound 1 consists of a one-dimensional (1D) chain constructed from [Ag(4,4′-bipy)]+ cations. With the connection of [Ag(4,4′-bipy)]+ cations and α-[SiW12O40]4− anions, two-dimensional (2D) structure was built. Because of the π–π stacking interactions between pyridyl rings of 4,4′-bipy from adjacent chains, three-dimensional (3D) structure was generated. Furthermore, the C–H ··· O weak interaction between and polytungstate made the structure more stable. Like 1, compound 2 is a three-dimensional (3D) supramolecular compound constructed from a transition-metal complex fragment [Cd2(dafo)4(4,4′-bipy)(H2O)2]4+, and free dafo through C–H ··· O weak interactions. To our best knowledge, it is the first time that saturated Keggin-type polyoxotungstates interact with dafo and 4,4′-bipy at the same time.

Synthesis, crystal structure, and characterization of a new high-dimensional phosphomolybdate architecture built from silver-complex fragments and hexa-connected P2Mo5 clusters

A new 3-D organic–inorganic hybrid phosphomolybdate, [Ag(bipy)]4(H2P2Mo5O23) · 3H2O (1) (bipy = 4,4′-bipyridine) has been hydrothermally synthesized and characterized by elemental analyses, IR, TG, and fluorescent properties. Compound 1 crystallizes in the monoclinic space group C2/c with a = 23.830(5), b = 21.030(4), c = 24.501(5) Å, β = 110.38(3)°, V = 11510(4) Å3, Z = 8, and R 1 (wR 2) = 0.0507 (0.1210). It contains unique 3-D metal organic frameworks based on silver-complex fragments and hexa-connected P2Mo5 clusters via covalent bonds and represents the highest connection numbers of P2Mo5 clusters to date.

Syntheses, crystal structures and photochemistry of two new organic–inorganic hybrid compounds based on copper–glycin complexes and paradodecatungstates

Two organic–inorganic hybrid materials built from copper–glycin complexes and paradodecatungstates, Na6[{Cu(gly)(H2O)}]2[{Cu(H2O)}(H2W12O42)] ⋅ 21H2O (1) and Na{Na(H2O)6}{Na(H2O)4}3[{Cu(gly)2}]2{H5(H2W12O42)} ⋅ 8.5H2O (gly = glycin) (2), have been synthesized in aqueous solution and characterized by IR, UV, TG, elemental analysis, electrochemistry, and single-crystal X-ray analyses. In 1, [H2W12O42]10− building block connects two neighboring clusters with [Cu(H2O)]2+ groups to produce an infinite 1-D chain; then these chains are linked through [Cu(gly)(H2O)]+ groups to form a 2-D layer structure, which is further joined by Na+ to form a 3-D network. In 2, [H2W12O42]10− decorated by two [Cu(gly)2] moieties connects four adjacent clusters with six Na+ into a 2-D layer. In addition, luminescence and photocatalysis properties of these compounds have been investigated.