Polyoxometalate‐Based Entangled Coordination Networks Induced by an Extended Bis(triazole) Ligand

The introduction of an extended bridging bis(triazole) ligand, that is, 4,4′‐bis(1,2,4‐triazol‐1‐ ylmethyl)biphenyl (BBPTZ), into the hydrothermal reaction system containing transition metal ions and Keggin‐type polyoxometalates (POMs) led to the isolation of three new organic–inorganic hybrid entangled coordination networks, [Cu^I₂Cu^II(BBPTZ)₆][SiW₁₂O₄₀]?12 H₂O ( 1 ), [Ni(BBPTZ)₂(H₂O)][H₂SiW₁₂O₄₀]?11 H₂O ( 2 ), and [Ni₂(BBPTZ)₄(H₂O)₂][SiW₁₂O₄₀]?3 H₂O ( 3 ). All three compounds were characterized by elemental analysis, IR spectroscopy, TG analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compound 1 contains a 2‐D POM‐based metal–organic layer entangled with 1‐D ladder‐like metal–organic chains. The adjacent 2‐D networks are parallel to each other, further stacking into a 3‐D supramolecular framework with 1‐D channels. Compound 2 exhibits a 1‐D cantilever‐type loop‐containing chain. The Keggin‐type POMs act as the cantilever groups, leading to the adjacent catilever‐type chains interwaving together to form a 3‐D supramolecular open framework with two types of channels. Compound 3 possesses a 3‐D open framework based on 2‐D metal–organic undulated layer and Keggin‐type POM clusters. Three sets of such frameworks further interpenetrate with each other to form an interesting three‐fold interpenetrating framework. The photocatalytic activities of compounds 1–3 for the decomposition of methylene blue (MB) under UV light have been investigated.     

An Organic‐Inorganic Hybrid Based on Keggin‐Type Polyoxometalate and Hypoxanthine: Synthesis,Structure, Stability,and Electrochemistry Properties

The organic‐inorganic hybrid H₅[Ag₂(hyp)₂]₂[BW₁₂O₄₀] · 9H₂O ( 1 ) (hpy = hypoxanthine), based on Keggin‐type polyoxometalate and hypoxanthine, was prepared by hydrothermal synthesis and characterized by single‐crystal and powder X‐ray diffraction, IR spectroscopy, elemental analysis, and thermogravimetry. The title compound has a two‐dimensional layer structure constructed by Keggin‐type [BW₁₂O₄₀]^5– anion, silver, and the biomolecule hyp. In addition, compound 1 exhibited excellent stability and superior activity in the electro‐catalytic oxidation of glucose.     

New Entangled Coordination Networks Based on Charge‐Tunable Keggin‐Type Polyoxometalates

Investigation into a hydrothermal reaction system with transition‐metal (TM) ions, 1,4‐bis(1,2,4‐triazol‐1‐lmethyl)benzene (BBTZ) and various charge‐tunable Keggin‐type polyoxometalates (POMs) led to the preparation of four new entangled coordination networks, [Co^II(HBBTZ)(BBTZ)_2.5][PMo₁₂O₄₀] ( 1 ), [Cu^I(BBTZ)]₅[BW₁₂O₄₀] ? H₂O ( 2 ), [Cu^II(BBTZ)]₃[AsW^V₃W^VI₉O₄₀] ? 10 H₂O ( 3 ), and [Cu^II₅(BBTZ)₇(H₂O)₆][P₂W₂₂Cu₂O₇₇(OH)₂] ? 6 H₂O ( 4 ). All compounds were characterized by using elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. The mixed valence of W centers in compound 3 was further confirmed by using XPS spectroscopy and bond‐valence sum calculations. In the structural analysis, the entangled networks of 1 – 4 demonstrate zipper‐closing packing, 3D polythreading, 3D polycatenation, and 3D self‐penetration, respectively. Moreover, with the enhancement of POM negative charges and the use of different TM types, the number of nodes in the coordination networks of 1 – 4 increased and the basic metal–organic building motifs changed from a 1D zipper‐type chain (in 1 ) to a 2D pseudorotaxane layer (in 2 ) to a 3D diamond‐like framework (in 3 ) and finally to a 3D self‐penetrating framework (in 4 ). The photocatalytic properties of compounds 1 – 4 for the degradation of methylene blue under UV light were also investigated; all compounds showed good catalytic activity and the photocatalytic activity order of Keggin‐type species was initially found to be {XMo₁₂O₄₀}>{XW₁₂O₄₀}>{XW_12?nTM_nO₄₀}.     

Keggin‐Type Polyoxometalate‐Based Metal–Organic Networks for Photocatalytic Dye Degradation

The reaction of Keggin‐type polyoxometalate (POM) units, transition‐metal (TM) ions, and a rigid bis(imidazole) ligand (1,4‐bis(1‐imidazolyl)benzene (bimb)) in a hydrothermal environment led to the isolation of four new POM‐based metal–organic networks, [H₂L][CuL][SiW₁₂O₄₀]?2 H₂O ( 1 ), [H₂L]₂[Co(H₂O)₃L][SiW₁₁CoO₃₉]?6 H₂O ( 2 ), KH[CuL]₂[SiW₁₁CoO₃₉(H₂O)]?2 H₂O ( 3 ), and [CuL]₄[GeW₁₂O₄₀]?H₂O ( 4 ; L=bimb). All four compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compounds 1 and 3 are new 3D networks with 1D channels. Compounds 2 and 4 contain 2D networks, which further stack into 3D supramolecular networks. The contributions of pH value, the negative charge of the POM, and the TM coordination modes to the construction of 3D networks were elucidated by comparing the synthetic conditions and structures of compounds 1 – 4 . The photocatalytic properties of compounds 1 – 4 were investigated using methylene blue (MB) degradation under UV light. All compounds showed good catalytic activity and structural stability. The possible catalytic mechanism was discussed on the basis of active‐species trapping experiments. The different photocatalytic activities of compounds 1 – 4 were explained by comparison of the band gaps of different POM species and different packing modes of POM units in these hybrid compounds.     

A 3D Metal‐organic Framework Containing [Cd(3‐CPOA)]n (3‐CPOA2– = 3‐Carboxyphenoxyacetato Dianion) Expanded by 4,4′‐Bipyridine

The hydrothermal reaction of Cd(NO₃) · 4H₂O with 4,4′‐bipyridine (bipy) and 3‐carboxyphenoxyacetatic acid (3‐H₂CPOA) afforded a 3D metal‐organic framework (MOF) [Cd(3‐CPOA)(bipy)]_n · 3.5nH₂O, which was characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and X‐ray diffraction. The single‐crystal structural analysis revealed that it has a Cds‐type topological network with 1D channels that contain encapsulated water molecular tapes.     

Synthesis,Crystal Structure,and Properties of the 3D Porous Framework [Zn(INAIP)]·DMA·H2O

A new three‐dimensional (3D) porous framework [Zn(INAIP)] · DMA · H₂O ( 1 ) [INAIP = 5‐(isonicotinamido)isophthalate, DMA = N,N′‐dimethylacetamide] was synthesized by solvothermal methods and characterized by single‐crystal and powder X‐ray diffraction, as well as thermogravimetric analysis. The results of X‐ray diffraction analyses revealed that complex 1 has an unusual 3D architecture with the (3,6)‐connected rutile ( rtl ) topology. The adsorption behavior shows that compound 1 exhibits selective adsorptions of CO₂ over N₂ after the removal of the solvent molecules within the pores.     

Two CdII/CoII‐Imidazolate Coordination Polymers: Syntheses,Crystal Structures,Stabilities, and Luminescent/Magnetic Properties

Cadmium(II) based 2D coordination polymer [Cd(L1)₂(DMF)₂] ( 1 ) (L1 = 4,5‐dicyano‐2‐methylimidazolate, DMF = N,N′‐dimethylformamide) and 2D cobalt(II)‐imidazolate framework [Co(L3)₄] ( 2 ) (L3 = 4,5‐diamide‐2‐ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction measurement (PXRD) and single‐crystal X‐ray diffraction. Compound 1 has hexacoordinate Cd^II ions and forms a zigzag chain‐like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 °C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co^II atom.     

Two 3D Polyoxometalate‐based Frameworks Constructed from Silver(I)‐triazole/tetrazole Units: Hydrothermal Syntheses,Crystal Structure and Properties

Two polyoxometalate‐based compounds constructed by Keggin/Ag/ L , namely [Ag₁₀( L₁ )₆(H L₁ )₂][HPMo₂^VMo^VI₁₀O₄₀] ( 1 ) and [Ag₁₀( L₂ )₈(H₂SiMo₁₂O₄₀)] ( 2 ) ( L₁ = 1,2,4‐1H‐triazole and L₂ = 1H‐tetrazole), were synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, elemental analyses, and IR spectroscopy. In compound 1 , the tetra‐nuclear Ag cycles constructed by four L₁ ligands, two Ag1 ions, and two Ag2 ions. Compound 1 exhibits a two dimensional (2D) metal‐organic layer containing adjacent tetra‐nuclear Ag cycles. Furthermore, the adjacent 2D layers are further extended by Ag ions to form a three dimensional (3D) channel‐like framework, with Keggin anions embedding in the channels. Compound 2 is isostructural with 1 . Additionally, the electrochemical and photocatalytic properties of the title compounds were investigated.     

Two Keggin Templated Supramolecular Compounds by Exerting the Chelate and Linking Dual Roles of the Ligand 2, 2′‐Biimidazole

Two new Keggin templated supramolecular compounds, [Zn₂(H₂biim)₅(SiM₁₂O₄₀)] · 4H₂O [M = W ( 1 ), Mo ( 2 )] (H₂biim = 2, 2′‐biimidazole), were synthesized under hydrothermal conditions by using the ligand 2, 2′‐biimidazole. They were characterized by single‐crystal X‐ray diffraction, elemental analyses, IR and photoluminescence spectroscopy as well as cyclic voltammetry. The two isostructural compounds are constructed by two discrete supramolecular moieties: the inorganic chains consist of Keggin anions and metal‐organic chains constructed by [Zn₂(H₂biim)₅]⁴⁺ subunits. In the dinuclear [Zn₂(H₂biim)₅]⁴⁺ subunit, the H₂biim ligands exhibit a dual role, chelating and linking. The metal‐organic chains further construct a 3D supramolecular framework with channels, in which the Keggin‐based inorganic chains are accommodated. The electrochemical behaviors of compounds 1 and 2 bulk‐modified carbon paste electrodes ( 1 ‐CPE, 2 ‐CPE) were studied.     

Synthesis,Characterization, and Photoluminescence Properties of a Planar Copper Triazolate Coordination Polymer with Cyanide as Co‐Ligand

A new copper coordination polymer [Cu₃(CN)(dmtz)₂] ( 1 ) (Hdmtz = 3,5‐dimethyl‐1,2,4‐triazole) was solvothermally synthesized and characterized by IR spectroscopy, X‐ray power diffraction, and single‐crystal X‐ray diffraction. The single‐crystal diffraction analysis shows that compound 1 belongs to the orthorhombic space group Pmmn, and exhibits a 2D planar framework constructed by the ligand dmtz and cyanide anions, in which the cyanide anion was generated from in situ decomposition of acetonitrile. The photoluminescent study indicates that 1 emits strong blue‐green luminescence with long emission lifetimes in the solid state at room temperature.     

Stable Heterometallic CuII‐BaII‐2,5‐Thiophenedicarboxylate Framework with High Capacity for Light Hydrocarbons

The heterometallic Cu^II‐Ba^II coordination polymer, namely [CuBa(tdc)₂(H₂O)(DMF)]_n ( 1 ) (H₂tdc = 2,5‐thiophenedicarboxylic acid, DMF = N,N′‐dimethylformamide), was solvothermally synthesized by the reaction of H₂tdc, CuCl₂ · 2H₂O, and Ba(NO₃)₂. Single crystal X‐ray diffraction analysis reveals that compound 1 features a 3D intricate framework with the 1D channels occupied by the coordinated solvent molecules. After removing the coordinated solvent molecules, the desolvated samples of 1a exhibit high capacity for light hydrocarbons.     

Synthesis,Crystal Structure,and Photocatalytic Properties of a Zinc(II) Coordination Polymer Based on 3‐Hydroxy‐2‐pyridinecarboxylic Acid

The zinc(II) compound, [Zn₃(HL)₆]_n ( 1 ) (H₂L = 3‐hydroxypyridine‐2‐carboxylic acid) was synthesized by a solvothermal reaction of Zn(NO₃)₂ · 6H₂O and 3‐hydroxypyridine‐2‐carboxylic acid as raw materials. The structure of complex 1 was determined by single‐crystal X‐ray diffraction analysis and further characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, as well as powder X‐ray diffraction. X‐ray structure analysis demonstrates that the complex crystallizes in the monoclinic system, space group P2₁/n. There are three zinc ions in the asymmetric unit, which are either five‐coordinate or six‐coordinate. The asymmetric units are further bridged by the carboxylate of the organic ligands, featuring a 2D framework. The solid state diffuse‐reflectance UV/Vis spectra reveals that complex 1 has semiconducting nature with the energy bandgap (E_g) estimated to be 3.11 eV. The photocatalytic properties of complex 1 in degradation of organic dyes were further investigated. Results showed that the complex could degrade 54 % of the dye methylene blue solution within 120 min under UV irradiation light and reused for five times without the decline of the photocatalytic activity.     

Porous GdIII‐Organic Framework as a Dual‐Functional Material for Cyanosilylation of Aldehydes and Ablation of Human Liver Cancer Cells

Metal‐organic frameworks (MOFs) have gained great attention in recent years because they could behave as multifunctional materials which combine the advances of porous solids and coordination complexes. With the aim of constructing multifunctional MOFs, in this study, we choose a Y‐shaped tricarboxylic ligand biphenyl‐3,4′,5‐tricarboxylic acid (H₃bpt) to react with Gd^III ions to afford a new dual‐functional lanthanide‐organic framework with the chemical formula of [Gd₂(bpt)₂(H₂O)₂] · (DMF)₂(H₂O)₆ ( 1 ) (DMF = N,N‐dimethylformamide) under solvothermal condition. The title complex was characterized by means of elemental analysis, FT‐IR spectroscopy, thermogravimetric and X‐ray diffraction analyses. Crystal structure analysis reveals that compound 1 is composed of 1D helical chain secondary building units that connect by the bpt^3– ligands into a 3D framework with 1D nanosized channels running along the b axis. In view of its high porosity and accessible open metal sites, the activated 1 ( 1a ) was studied for the cyanosilylation of aldehydes under solvent‐free conditions. The catalytic activity of 1a is much higher than that of compound 1 , indicating that the exposed open metal sites of 1a is beneficial to the cyanosilylation reaction. In connection to these, the different cytotoxicities of 1 and 1a were also evaluated on four human liver cancer cells (SMMC‐7721, Bel‐7402, MHCC97 and Hep3B) by the MTT assay.     

Synthesis of Pyrazolo‐[4́,3́:5,6]pyrido[2,3‐d]pyrimidine‐diones Catalyzed by a Nano‐sized Surface‐Grafted Neodymium Complex of the Tungstosilicate via Multicomponent Reaction

An inorganic–organic hybrid based on lanthanide clusters and Keggin type polyoxometalates (POMs) (Na[Nd (pydc‐OH)(H₂O)₄]₃}[SiW₁₂O₄₀]) was used the first time as trinuclear catalyst for one pot synthesis of pyrazolo[4??,3?:5,6]pyrido[2,3‐d]pyrimidine‐diones, via two different four and five‐component reactions involving hydrazine hydrate, ethyl acetoacetate, aryl aldehydes, and 6‐amino‐1,3‐dimethyl uracil or barbituric acid with ammonium acetate as alternative materials in green condition. To evaluate potential application of the as‐made hybrid in adsorption and separation processes, nitrogen adsorption was performed at 77 K through simulation study. The hybrid catalyst was further characterized via powder X‐ray diffraction (PXRD) at room temperature which indicated the good phase purity of the catalyst. The results show that the catalytic activity of the hybrid catalyst has increased relative to each parent component due to the special interaction between Keggin anions and pydc‐OH ligands.     

(3,4)‐Connected Twofold Interpenetrated Network with Right‐ and Left‐Handed Helical Chains: Synthesis,Crystal Structure,and Luminescence Sensing

The zinc(II) coordination polymer Zn₂(L)₂(bix)₂ · 2H₂O ( 1 ) [H₂L = 4,4′‐methylenebis(oxy)dibenzoic acid, bix = 1,4‐bis(imidazole‐1‐yl‐methylene)‐benzene] was synthesized by hydrothermal reaction. The title compound was characterized by single‐crystal X‐ray diffraction analysis, IR spectroscopy, and elemental analysis. The crystal structure determination reveals that compound 1 displays a twofold interpenetrated 3D framework, in which the Zn atoms are connected by the H₂L ligands into interesting right and left‐handed helical chains. Topological analysis reveals that the title compound displays a (3,4)‐connected (6³) (6⁵ · 8) topology. The solid‐state luminescent spectra was studied. Furthermore, the dispersed solution of compound 1 in DMF exhibits strong fluorescent emission, which could be quenched by trace amount of nitrobenzene.     

Solvothermal Synthesis and Structural Characterization of an Organic‐Templated New Aluminogermanate with the GIS Topology

A new organic‐templated aluminogermanate [C₄H₁₂N][AlGe₃O₈] ( 1 ) has been prepared under solvothermal conditions by using 2‐propanol as solvent. The structure of the title compound was characterized by IR spectroscopic, elemental analysis, TG, single‐crystal X‐ray diffraction and powder X‐ray diffraction. Compound 1 crystallizes in the tetragonal space group I4₁/a, a = b = 10.7754(8) Å, c = 9.9116(14) Å, V = 1150.8(2) Å³, Z = 4. The structure of the title compound shows eight‐membered ring channels along a and b axes with a typical GIS topology, and – most importantly – the structure of the inorganic framework is retained when the organic amine is removed by calcination.     

Synthesis and Characterization of a Two‐Dimensional Zinc Phosphite,Zn3(tren)(HPO3)3·xH2O (x ≈ 0.5; tren = tris(2‐aminoethyl)amine)

A new zinc phosphite with the formula Zn₃(tren)(HPO₃)₃·xH₂O (x≈0.5) has been synthesized under hydrothermal conditions and characterized by FTIR, elemental analysis, powder X‐ray diffraction, single‐crystal X‐ray diffraction, thermogravimetric analysis and its fluorescent spectrum. The compound crystallizes in the triclinic system, space group (No.2), a = 10.1188(9) Å, b = 10.4194(9) Å, c = 10.5176(9) Å, α = 60.763(2)°, β = 70.6150(10)°, γ = 80.725(2)°, V = 912.77(14) ų, Z = 2. The structure consists of double crankshaft chains, which are linked by Zn‐O‐P bonds to form 8‐ and 12‐membered channels along the [100] direction. The claw‐like Zn‐centered complexes of Zn(N₄C₆H₁₈) as the supported templates, hang into the 12‐MR channels through Zn‐O‐P linkages with framework.     

Counterion‐Directed Assembly of Praseodymium(III) Compounds based on the Flexible Ligand 5‐Aminotetrazole‐1‐propionic Acid (Hatzp)

Different kinds of counterions (such as NO₃^–, ClO₄^–, and Cl^–) play a special role in controlling the framework of coordination compounds. Using this strategy, 5‐aminotetrazole‐1‐propionic acid (Hatzp) was selected to react with praseodymium(III) nitrate or perchlorate in the same solvent system, producing two different coordination compounds, [Pr₂(atzp)₄(H₂O)₈] · 2NO₃ · 2H₂O ( 1 ) and [Pr₂(atzp)₆(H₂O)₂] · H₂O ( 2 ). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. X‐ray diffraction analysis revealed that compound 1 displays a dinuclear structure, whereas 2 shows a one dimensional zigzag chain framework. Furthermore, the luminescence properties of compounds 1 and 2 were investigated at room temperature in the solid state.     

Crystal Growth and Structure Determination of Pigment Orange 82

The crystal structure of the important industrial orange pigment PO82, major part of the BASF Colors & Effects^® product Sicopal^® Orange K/L 2430, was solved from combined X‐ray single crystal, X‐ray and neutron powder diffraction, ¹¹⁹Sn Mössbauer spectroscopy, transmission electron microscopy, electron diffraction, and chemical analyses. The structure contains Keggin type clusters composed of four [M₃O₁₃] trimers consisting each of three MO₆ octahedra that share edges and one common oxygen atom connecting the trimers to the central ZnO₄ tetrahedron. The octahedrally coordinated metal atom position is mixed occupied by Ti⁴⁺, Sn⁴⁺, and Zn²⁺. Adjacent Keggin clusters share vertices and are further interconnected to four ZnO₄ tetrahedra. This framework of interconnected MO₆ octahedra and ZnO₄ tetrahedra contains channels along [110], in which the Sn²⁺ cations are located.     

Solvent Molecule Controlled Zinc(II) Metal‐Organic Frameworks with Different Topology

Two zinc(II) coordination polymers, namely [Zn₂(bptc)(DMF)₂(H₂O)]_n ( 1 ) and [Zn(bptc)_0.5(DMA)]_n ( 2 ) (H₄bptc = biphenyl‐3,3′,5,5′‐tetracarboxylic acid, DMF = N,N′‐dimethylformamide, DMA = N,N′‐dimethylacetamide), were obtained under solvothermal conditions by varying the reaction solvents. Single crystal X‐ray diffraction analyses revealed that compound 1 features a 3D PtS type framework based on dinuclear [Zn₂O(COO)₂] subunits and compound 2 features a 3D lvt type framework based on paddle‐wheel shaped [Zn₂(COO)₄] subunits. Moreover, the luminescent and thermal stabilities of these two compounds were investigated.