A novel polyoxometalate-based metal-organic compound constructed from an unprecedented [Ag8(Hpyttz)4(H2pyttz)2] cluster and an in-situ [VW12O40]3 − anion

A novel polyoxometalate (POM)-based metal-organic compound constructed from a multinuclear Ag^I cluster and Keggin-type [VW₁₂O₄₀]^3 − anion, [Ag₄(Hpyttz)₂(H₂pyttz)][HVW₁₂O₄₀]·3H₂O (1) (H₂pyttz = 5′-(pyridin-4-yl)-1H,2′H-3,3′-bi(1,2,4-triazole), was hydrothermally synthesized and characterized by IR spectroscopy, TG analysis, powder and single-crystal X-ray diffraction. In compound 1, [VW₁₂O₄₀]^3 − (VW₁₂) was in-situ transformed from [SiW₁₂O₄₀]^4 − anion. Eight Ag^I ions were connected by six Hpyttz/H₂pyttz ligands with three coordination modes forming an unprecedented [Ag₈(Hpyttz)₄(H₂pyttz)₂] cluster, which connected with six VW₁₂ anions to construct a 2-D double-layer (3,6)-connected network with {4³}₂{4⁶.6⁶.8³} topology. Moreover, the photocatalytic activity of 1 has been investigated.     

A dinuclear copper(II) complex and a zigzag chain iron(II) polymer based on the 4-antipyrine derived Schiff base ligands: The hydroxylation and redox occurred under the solvothermal conditions

A new dinuclear copper(II) compound, [Cu₂(L1-O)₂] (1) (L1 = (4E)-4-(2-hydroxybenzylideneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one), and zigzag chain polymer, {[FeCl₂(L2)]}_n (2) (L2 = 1,5-dimethyl-2-phenyl-4-{[(1E)-pyridine-4-ylmethylene]amino}-1,2-dihydro-3H-pyrazol-3-one), were synthesized by solvothermal reactions and structurally characterized. The methyl group hydroxylation and the redox have been observed in the preparation of 1 and 2, respectively.     

Trinuclear Ru(II) polypyridyl complexes as human telomeric quadruplex DNA stabilizers

Two new trinuclear ruthenium(II) complexes [(bpy)₆Ru₃(tpbip)]⁶⁺ (1) and [(bpy)₆Ru₃(tptaip)]⁶⁺ (2) (bpy = 2,2′-bipyridine, tpbip = 1,3,5-tris(1,10-phenanthroline-[5,6-d]imidazol-2-yl)-benzene, tptaip = 2,4,6-tri(1,10-phenanthroline-[5,6-d]imidazol-2-yl)-1,3,5-triazine) have been synthesized and characterized. The interaction of human telomeric DNA with Ru(II) complexes was explored by means of CD spectroscopy, fluorescence titration, ITC and FRET melting. Results indicated that two complexes not only induce a remarkable conformational change of human telomeric DNA, but also have the ability to stabilize the G-quadruplex.     

Syntheses,structures and luminescence of two cadmium entangled coordination polymers based on bis(imidazole) and biscarboxylate ligands

Two entangled coordination polymers [Cd₂(bib)(bdc)₂]_n (1) and [Cd₂(bib)(bda)₂]_n (2) were synthesized by the hydrothermal reaction (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, bdc = 1,2-benzenedicarboxylate, bda = 1,4-benzenediacetate). 1 exhibits an unusual 6-connected self-catenated 3D network based on Cd₂(COO)₂ dimer with the point symbol of (4⁴·6¹⁰·8). 2 exhibits a 3-fold interpenetrating 3D pcu network based on Cd₂(COO)₂ dimer. The different conformations of bib ligands (the anti–anti–anti conformation in 1 and gauche–anti–gauche conformation in 2) play the key role in the construction of different structures in 1 and 2. The luminescence and thermal stability were investigated.     

Self-assembly of novel supramolecular silver(I) compound based on mixed ligands bipy/TST3−, H3TST = 2,4,6-tris (4-sulfophenylamino)-1,3,5-triazine

The novel supramolecular silver(I) compound with formula [Ag₆(TST)₂(bipy)₆(H₂O)₂]_n · 3nH₂O (1) based on assembly of Ag(I) and mixed ligand bipy/TST³⁻, bipy = 2,2′-bipyridine, H₃TST = 2,4,6-tris(4-sulfophenylamino)-1,3,5-triazine, has been prepared by hydrothermal method. In the solid-state structure of 1, two-dimensional layered polymeric structures extended with subunits [Ag₆(TST)₂(bipy)₆(H₂O)₂] interact each other in the form of π–π attractions between bipy, forming a three-dimensional supramolecular architecture. Compound 1 represents a Ag-containing polymeric compound possessing room-temperature luminescence.     

A lamella 2D silver(I) coordination polymer constructed from in situ generated 2-mercaptobenzoic acid

The reaction of Ag₂O and 2,2′-dithiodibenzoic acid (dtba) under ultrasonic condition gave rise to a novel metal–organic coordination polymer [Ag₄(2-mba)₂·(H₂O)₂]_n (1) (2-H₂mba = 2-mercaptobenzoic acid) involving in situ generated 2-mba ligand. Complex 1 shows a lamella 2D structure with a 6³-hcb net which is comprised of fused Ag₆ hexagonal rings. Moreover, 1 exhibits photoluminescence maximized at 468 nm upon 330 nm excitation at room temperature, which may be assigned to a ligand-to-metal charge transfer (LMCT) transition. Semiconducting behavior was also measured at room temperature with σ value of 3.24 × 10^?5 S cm^?1.     

A three-dimensional zincic molybdenum (V) phosphate with helical channel: Synthesis,structure, and electrochemical properties

A new reduced zincic molybdophosphate, (H₂bpp)₃[Zn₃Mo₁₂^VO₂₄(OH)₆(H₂O)₂(HPO₄)₆(PO₄)₂]·2H₂O 1 (bpp = 1,3-bis(4-pyridyl)propane) has been hydrothermally synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. Compound 1 crystallizes in the tetragonal space group I 41/a c d with a = 31.8033(4) Å, b = 31.8033(4) Å, c = 34.5593(8) Å, V = 34955.0(10) ų, and Z = 16 and exhibits a 4,6-connected 3-D framework with (3².8⁴)(3⁴.4².8³.9⁵.10) topology. The basic building blocks of [Zn(2)(Mo₆P₄)₂] are linked through [Zn(3)O₆] octahedra and [Zn(1)O₄] tetrahedra to construct 1-D chains along four different directions. Such 1-D chains are further connected by [Zn(1)O₄]²⁺ linkers to form a 3-D intricate framework with helical channels occupied by protonated bpp and water molecules. Additionally, the electrochemical property of the 1-CPE has been studied in detail.     

A new 2D 5-connected coordination polymer based on 3,4-bis(pyridin-4-ylmethoxy)benzoic acid ligand

A new 2D 5-connected coordination polymer [Zn₃(HL²)(1,4-bdc)₃] (1) (HL² = 3,4-bis(pyridin-4-ylmethoxy)benzoic acid, 1,4-H₂bdc = 1,4-benzenedicarboxylate) has been hydrothermally constructed using HL², 1,4-bdc ligands as linear linkers and Zn₃-clusters as 5-connected nodes. In addition, powder X-ray diffraction, photoluminescent property and thermogravimetric analysis for 1 are investigated in detail.     

A new (4,8)-connected topological MOF as potential drug delivery

A new compound of (NH₂(CH₃)₂[Zn₃(L)₂·3.5DMF]) (1) (H₄L = 1,1′,4′,1″,4″,1‴-quaterphenyl-3,5,3‴,5‴-tetracarboxylic acid 1,3,5-benzenetrisbenzoate) was synthesized and characterized. The coordination polymer shows an unusual 4,8-connected 3D net with (4⁶)₂(4¹²·6¹²·8⁴) topology. The incorporation of the drug 5-fluorouracil (5-FU) into the desolvated 1 was around 22.5 wt.% per gram of dehydrated 1. 5-Fu is released in a highly controlled and progressive fashion with 92% of the drug released after 120 h. The result from this work provides a new avenue for MOF to be used as potential drug delivery.     

A novel Wells–Dawson polyoxometalate-based metal–organic framework constructed from the uncommon in-situ transformed bi(triazole) ligand and azo anion

A novel Wells–Dawson polyoxometalate (POM)-based metal–organic framework (MOF) constructed from bi(triazole) ligand and azo anion, namely, [Ag₁₃(L)₆(N₂)(HP₂W₁₈O₆₂)] (1) (HL = 4-(1 H-1,2,4-triazol-3-yl)-2 H-1,2,4-triazolyl) has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR spectra, PXRD analysis. In compound 1, the rigid bi(triazole) ligands connected Ag^I ions to construct a 2D metal–organic layer, which was further extended by azo anions forming a 3D framework. The Wells–Dawson type [P₂W₁₈O₆₂]^6 − anion as a multidentate inorganic ligand coordinated with the Ag^I ions, consolidating the 3D MOF. The L ligands and azo anions were in-situ transformed from a bi(triazole) derivative, which has never been observed in previous reports. In addition, the electrocatalytic and photocatalytic properties of compound 1 have been investigated.     

A photoluminescent 3D silver(I) polymer with mixed 2-naphthol-5-carboxylate and hexamethylenetetramine ligands,showing an unusual (3,4)-connected (6·7·8)2(4·6·7)2(4·7·8)2(72·8)2(62·7·83)(62·72·8·10) topology

The reaction of AgClO₄ with 2-naphthol-5-carboxylic acid (HL) and hexamethylenetetramine (hmt) in the presence of 2,6-dimethylpyridine afforded a photoluminescent three-dimensional (3D) Ag^I polymer {[Ag₆(L)(μ₃-hmt)₂(μ₄-hmt)₂(ClO₄)](ClO₄)₄(H₂O)}_∞ (1), which exhibited an unusual (3,4)-connected (6·7·8)₂(4·6·7)₂(4·7·8)₂(7²·8)₂(6²·7·8³)(6²·7²·8·10) topological network (L = 2-naphthol-5-carboxylate). Moreover, the luminescent properties of 1 have been briefly investigated.     

Synthesis,topology analysis and luminescent property of a 3D AgCN coordination polymer based on 2-tptz (2-tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazin)

The solvothermal reaction of AgCN with 2-tptz (2-tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazin) afforded a 3D coordination polymer [(AgCN)₃(2-tptz)]_n (1). It was characterized by infrared spectroscopy, elemental analysis and X-ray single-crystal analysis. The structure of this polymer features a 2D wavelike [AgCN]_n substructure constructed from 18-membered of Ag₆(CN)₆ rings and 22-membered of Ag₈(CN)₆C₂ rings. When silver?sliver interactions are taken into account, the structure of 1 exhibits a (3 · 8 · 9)(4 · 8 · 9)(3 · 4 · 8 · 9³)(3 · 8 · 9² · 10²) topological network which has not been reported for the (3, 4)-connected nets. The photoluminescent property of the present coordination polymer was also investigated.     

Structural conversion of cubane-type thallium complex to hexagon silver complex by solid-state mechanochemical reaction

Solid-state structural transformation of Tl^I supramolecular polymer comprised from cubane-type thallium complex of [Tl₄(μ₃-4-BN)₄] (1) (4-HBN = 4-hydroxy benzonitrile) to Ag^I coordination polymer with three nuclear units of [Ag₃(μ₃-4-BN)₂(μ₄-4-BN)] (2) has been studied upon mechanochemical reaction of compound 1 with AgNO₃.     

A rare (3, 6, 10)-connected net containing both Zn2(COO)4 and Zn4(COO)8 units

A novel coordination polymer [Zn₃(btrc)₂(L1)]_n (1) (H₃btrc = 1, 2, 4-benzenetricarboxylic acid; L1 = 1, 3-bis(4-pyridyl)propane) has been synthesized under hydrothermal conditions. Single crystal X-ray diffraction study reveals that polymer 1 presents an unusual example of (3, 6, 10)-connected net with (4·6·7) (5²·6⁶·7⁷) (4¹⁶·5¹²·6⁴·7¹³) topology symbol, where btrc^3?, Zn₂(CO₂)₄, and Zn₄(CO₂)₈ units act as three-, six-, and ten-connecting nodes, respectively. In addition, the IR spectra, luminescence properties and thermogravimetric analysis of this polymer are investigated in this study.     

A novel 3D Nd(III) metal-organic frameworks based on furan-2,5-dicarboxylic acid exhibits new topology and rare near-infrared luminescence property

A rare lanthanide metal-organic framework (Ln-MOFs) based on Nd(III) binuclear nodes, with formula {[Nd₂(H₂O)₃(FDA)₃(CH₃OH)]⋅ CH₃OH}_n (1) (H₂FDA = furan-2,5-dicarboxylic acid), was obtained under solvothermal conditions and characterized by single crystal X-ray diffraction, thermogravimetric analysis and luminescent measurements. 1 has two type of Nd₂ binuclear clusters stabilized by carboxylic groups and exhibits a new topology structure. It is a four nodes 3,3,5,6-connected net with the point symbols of (4.5.6)₂(4.6²)₂(4².5⁴.6².7²)₂(5².6⁶.7⁴.9².10). Moreover, the near-infrared (NIR) luminescence of 1 based on Nd(III) and H₂FDA were investigated in the solid state at room temperature for the first time.     

Organometallic boxes built from 5,10,15,20-tetra(4-pyridyl)porphyrin panels and hydroxyquinonato-bridged diruthenium clips

Self-assembly of 5,10,15,20-tetra(4-pyridyl)porphyrin (tpp-H₂) tetradentate panels with dinuclear arene ruthenium clips [Ru₂(η⁶-arene)₂(dhbq)Cl₂] (arene = C₆H₅Me, p-PrⁱC₆H₄Me, C₆Me₆; dhbq = 2,5-dihydroxy-1,4-benzoquinonato) affords the cationic organometallic boxes [Ru₈(η⁶-C₆H₅Me)₈(tpp-H₂)₂(dhbq)₄]⁸⁺ ([1]⁸⁺), [Ru₈(η⁶-p-PrⁱC₆H₄Me)₈(tpp-H₂)₂(dhbq)₄]⁸⁺ ([2]⁸⁺) and [Ru₈(η⁶-C₆Me₆)₈(tpp-H₂)₂(dhbq)₄]⁸⁺ ([3]⁸⁺). These octanuclear cations have been isolated as their triflate salts and characterised by mass spectrometry, NMR and IR spectroscopy. The molecular structure of these systems was deduced by one-dimensional and two-dimensional NMR experiments (ROESY, COSY, HSQC).     

Two new polyoxometalate-based metal-organic complexes constructed from two in-situ transformed ligands through different ways

Two new Keggin-type polyoxometalates-based metal–organic complexes: [Ag₃(L1)₃(PMo₁₂O₄₀)]·3H₂O (1) and Ag₄(L2)₂(HL2)(PW₁₂O₄₀)Na₂(μ-OH)]·1.5H₂O (2) (L1 = 1.2.4-triazole, HL2 = 4-amino-1,2,4-triazole) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction analyses, IR spectra and powder X-ray diffraction analyses. In compound 1, the [Ag₆(L1)₆] crown-shaped ring was clamped by two [PMo₁₂O₄₀]^3 − polyanions, forming a sandwich-like [Ag₆(L1)₆(PMo₁₂O₄₀)₂] unit, which was extended to a 1D supramolecular chain through hydrogen bonding interaction. Compound 2 is a 3D metal–organic framework containing the [Ag₆(L2)₄(HL2)₂] crown-shaped ring and 1D [Na₂(PW₁₂O₄₀)(μ-OH)]_n inorganic chains, which represents a novel (3,3,4,6,10-c)-connected 3D topological framework. The L1 and L2 ligands were in-situ transformed from two different N-heterocyclic amide ligands through different ways, respectively. In addition, the electrocatalytic and photocatalytic activities of the title compounds have been studied.     

Novel silver(I) compounds assembled from hybrid ligands based on linear or T-shaped coordination environment

Two novel 1D compounds {[Ag₃(Hbptc)(bpa)₂]·H₂O}_n (1) and [Ag₂(H₂bptc)(bpp)₂]_n (2) (H₄bptc = 3,3′,4,4′-benzophenonetetracarboxylic acid, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane) were synthesized and structurally characterized. The crystal structures of compounds exhibit two kinds of ladder-like chains based on linear or T-shaped coordination environment of Ag(I). Fluorescence spectra of compounds 1 and 2 indicate the unusual intensity of fluorescent emission upon photoexcitation which may be attributed to ligand-to-metal charge transfer and Ag–Ag interactions.     

Novel two-dimensional Co(II) and Cd(II) coordination polymers with intriguing net topologies

Three new two-dimensional coordination polymers were constructed from 2,6-bis(imidazole-1-yl)pyridine (2.6-bip), terephthalic acid (1,4-bdcH₂), and M(NO₃)∙nH₂O (M = Co, Cd). [M(2,6-bip)(1,4-bdc)] (1: M = Co; 2: M = Cd) were prepared under hydrothermal condition, whereas [Cd(2,6-bip)(1,4-bdc)∙xDMF] (3) was obtained under solvothermal condition in DMF solvent. Single-crystal X-ray analyses revealed the first example of a 2D 4-connected net of 6⁶ topology in 1 and 2 and a rare 2D 4,5-connected net of 4,5 L20 topology in 3. All these complexes were thermally robust and emissive in solid-states. This work confirmed the versatility of using hingelike 2,6-bip as a linker and the importance of solvent effect in the process of framework formation.     

Fluorescent selectivity for small molecules of two coordination polymers based on a tetracarboxylate ligand

Two coordination polymers [Cd(tptc)_0.5(4,4′–bibp)]_n (1) and {[Zn₃(Htptc)₂(phen)₂]·1.5H₂O}_n (2) (H₄tptc = terphenyl-3,3″,5,5″-tetracarboxylic acid, 4,4′-bibp = 4,4′-bis(imidazolyl)biphenyl, and phen = 1,10-phenanthroline) were synthesized under solvothermal conditions. Complex 1 displays a 3D structure with a Schläfli symbol of {4⁴.6²}{4⁸.6²⁰}. Complex 2 possesses a 2D layer network, incorporating [Zn₃(COO)₆] second building units (SBUs), which is packed into a 3D supramolecular architecture by π ⋯ π interactions. Both of them exhibit strong luminescence characteristics. It is worth to note that complexes 1 and 2 show potential application to detect small organic molecules.