Assembly of one 2D layer and two 3D pillared-layer structures derived from metal ions and 5-(pyridin-4-yl)isophthalic acid with or without pillars

Three new coordination polymers, [Mn(L)(H₂O)₂]₂·5H₂O (1), [Cu(L)(4,4′-bipy)]₂·H₂O (2) and [Pb(L)(4,4′-bipy)_0.5] (3) (H₂L = 5-(pyridin-4-yl)isophthalic acid; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by IR, thermogravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. Complex 1 shows a 2D layer structure which stacks with the other ones to form 1D channels to hold 1D water chains. Complex 2 displays a 3D + 3D → 3D polycatenation network. 3 shows a unique 2D + 2D → 3D polycatenation net in which each Pb center has a hemidirected coordination geometry due to the existence of “inert pair effect”. The thermal and luminescent properties of 1–3 were also examined.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Synthesis,structural characterization and properties of a novel 1D helical chain arsenomolybdate {[Cu(en)2][Cu(en)(H2O)][(Cu(en)2(H2O)] [AsIIIAsVMo9O34)]} · 2H2O

An organic–inorganic hybrid 1D helical chain arsenomolybdate {[Cu(en)₂][Cu(en)(H₂O)][(Cu(en)₂(H₂O)] [As^IIIAs^VMo₉O₃₄)]} · 2H₂O (1) (en = ethylenediamine) has been hydrothermally synthesized and characterized by elemental analyses, IR, UV and CD spectrum, powder X-ray diffraction, TG-DTA and single-crystal X-ray diffraction. The asymmetric unit of 1 consists of a monocapped trivacant Keggin [As^IIIAs^VMo₉O₃₄]^6 − subunit, a pendant [Cu(en)₂(H₂O)]^2 + cation, a pendant [Cu(en)(H₂O)]^2 + cation, one bridging [Cu(en)₂]^2 + cation and two lattice water molecules. It should be noted that 1 illustrates a one-dimensional (1D) helical chain assembled by {[Cu(en)(H₂O)][(Cu(en)₂(H₂O)][As^IIIAs^VMo₉O₃₄)]}^2 − clusters and [Cu(en)₂]^2 + linkers.     

The irreversible crystal transformation of a novel Cadmium(II) supramolecular complex containing planar tetrameric water cluster

A new cadmium complex [CdL₂(CH₃COO)₂] · 3H₂O (1) has been synthesized by the reaction of 2-aminobenzimidazole (L) with cadmium acetate in an aqueous solution, and structurally characterized by single crystal X-ray diffraction and FT-IR spectra. Cyclic planar tetrameric water clusters with C_2h symmetry are observed to be encapsulated in the 3D open supramolecular architecture of 1 by hydrogen bonds interactions. Interestingly, 1 can convert irreversibly into single crystal 1a formulated [CdL₂(CH₃COO)₂] by losing its lattice water molecules at room temperature. Strong intermolecular N–H ⋯ O hydrogen bonds and aromatic rings π–π stacking interactions assemble 1a into another 3D interdigitated supramolecular network.     

Synthesis,characterizations, and crystal structure of a novel 2D metal phosphonate: Na2[Cd2(H2O)3(O3PCH(OH)CO2)2] · 2H2O

A novel cadmium phosphonate compound Na₂[Cd₂(H₂O)₃(O₃PCH(OH)CO₂)₂] · 2H₂O (1) has been synthesized by hydrothermal reaction at 120 °C and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, elemental analysis and thermogravimetric analysis. The structure of compound 1 comprises CdO₆ octahedra and CdO₇ pentagonal bipyramid connected by [O₃PCH(OH)CO₂]³⁻ to form a 2D layered structure with a one-dimensional channel system and the charge-compensating Na⁺ cations being located between two adjacent layers.     

Novel 3-dimensional sixfold interpenetrating diamondoid networks of copper(I) coordination polymers of polypyridyl ligands – Syntheses,characterization and crystal structures

Two new coordination polymers [Cu(L¹)₂]_n(ClO₄)_n·2nH₂O (1), [Cu(L²)₂]_n(ClO₄)_n·2nH₂O (2) of polydentate imine/pyridyl ligands, L¹ and L² with Cu(I) ion have been synthesized and characterized by single crystal X-ray diffraction studies, elemental analyses, IR′ UV–vis and NMR spectroscopy. They represent 3-dimensional, sixfold interpenetrating diamondoid network structures having large pores of dimension, 35 × 21 Å² in 1 and 38 × 19 Å² in 2, respectively.     

Syntheses,structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H₂N(CH₃)₂]₈H₃[LnNa(H₂O)₄(OH)WO(H₂O) (B-α-AsW₉ O₃₃)₂]·8H₂O [Ln = La^III (1), Ce^III (2), Pr^III (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na₂WO₄·2H₂O, C₂H₇N·HCl, NaAsO₂ and Ln(NO₃)₃·6H₂O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H₂O)₄(OH) WO(H₂O)(B-α-AsW₉O₃₃)₂]^11 − polyanion consists of two trivacant Keggin [B-α-AsW₉O₃₃]^9 − moieties linked by one [WO(H₂O)]^4 + group and a dimeric [LnNa(H₂O)₄(OH)]^3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.     

Binuclear, 2D grid and 3D interlocking coordination polymers based on 1,2,4,5-benzenetetracarboxylic acid and 4,4′-azobispyridine

Three new nickel(II) complexes [Ni₂(btec)(azopy)₂(H₂O)₈]·2H₂O (1), {[Ni(H₂btec)(azopy)(H₂O)₂]·(azopy)}_n (2) and {[Ni₄(btec)₂(azopy)₃(H₂O)₁₀]·8H₂O}_n (3) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid; azopy = 4,4′-azobispyridine) have been synthesized by tuning the reaction temperature and the metal–ligand ratio. They were characterized by single-crystal X-ray diffraction and elemental analysis. 1 shows a binuclear structure, 2 exhibits a 2D grid, and 3 features an interesting 3D framework with (6³)(4.6²)(4².6².8²) topology formed by two types of interlocked 2D layers.     

Synthesis,crystal structures and NIR luminescence properties of binuclear lanthanide Schiff Base complexes

Three binuclear lanthanide complexes [Nd₂(L¹)₃(MeOH)]·MeOH·H₂O (1) and [Ln₂(H₂L²)₂(OAc)₄]·2(CF₃SO₃)·MeOH·EtOH (Ln = Nd (2) and Ho (3)) were prepared using two Schiff base ligands. Interestingly, 1 has a triple-decker structure with two lanthanide ions enclosed by three rigid conjugated Schiff base ligands (H₂L¹), while 2 and 3 show nanoscale ring structures (8 × 12 × 12 Å) formed by flexible long-chain Schiff base ligands (H₂L², ~ 23 Å) with the lanthanide ions located in the center. Upon excitation of the ligand-centered absorption bands, 1–2 and 3 show typical NIR emission spectra for Nd^3 + and Ho^3 + ions, respectively. In 1, the Nd(III) centers are shielded within the decker-like structure and surrounded by chromogenic Schiff base ligands (energy transfer donors). Luminescence studies show that the NIR emission lifetime of 1 is longer than that of 2 in solution.     

Tuning structural topologies of two coordination polymers via alter N-donor auxiliary ligand

Based on the N-donor auxiliary ligand effect, two new Ni(II) coordination polymers [Ni₂(HL)₂(bpe)₂] (1) and [Ni(HL)(bipy)(H₂O)₂] (2) [H₃L = 2-(4′-carboxyphenyl)terephthalic acid; bpe = 1,2-bis(4-pyridyl)ethane; bipy = 4,4′-bipyridine] have been successfully synthesized and characterized by single-crystal X-ray diffraction study, elemental analysis, IR spectra, TGA and powder X-ray diffraction (PXRD). This work presents a comparative study on the tuning of structural topologies by using two N-donor ligands with different lengths as auxiliary ligands. The structural determination reveals that complex 1, incorporating bpe ligands, features a three-dimensional (3D) 4-connected 4-fold dia interpenetrating architecture with the point symbol of 6⁶, while 2, containing bipy ligands, exhibits a two-dimensional (2D) sql layer structure with a 4-connected (4⁴·6²) topology. Moreover, the magnetic properties for 1 and 2 were also measured and compared on account of their different structures.     

One 2D anionic coordination polymer with {[Co(H2O)6]}2 + cationic guest for fast and selective adsorption of cationic dyes

One new anionic Coordination Polymer, namely [Co(H₂O)₆]^2 +·[Co₃(bptc)₂(H₂O)₁₀]^2 −·3H₂O (1), where H₄bptc = 3,3′,5,5′-biphenyltetracarboxylate, has been synthesized hydrothermally and characterized. In compound 1, bptc^4 − as tridentate ligands connect the Co^2 + cations to form a 2D layer with 1D pseudo channels encapsulation of [Co(H₂O)₆]^2 + guest. In addition, their adsorption activities for organic dyes were investigated in aqueous solution. The results suggested that the anionic complex 1 show rapid and selective adsorption of cationic dyes for Neutral red, Methylene blue.     

A banana-shaped iron(III)-substituted tungstogermanate containing two types of lacunary polyoxometalate units

A novel polyoxotungstate cluster (H₂en)_2.5H₉[Fe₆Ge₃W₂₄O₉₄(H₂O)₂] · 14H₂O (1) (en = ethylenediamine) has been hydrothermally synthesized and structurally characterized by IR, TGA and single-crystal X-ray diffraction. The polyoxoanion skeleton of 1 is composed of two tri-Fe^III substituted B-α-(Fe₃GeW₉O₄₀) Keggin units connected by an unique hexavacant GeW₆O₂₆ Keggin fragment, leading to the first Fe(III)-containing banana-shaped tungstogermanate. Magnetic measurements of 1 reveal that the exchange interactions within the trimetal clusters are antiferromagnetic.     

A novel organic-inorganic hybrid polyoxometalate-based 3D framework constructed by organo-functionalized [As2W21O72(mal)2]18 − units and Ce3 + ions

A novel organic-inorganic hybrid polyoxometalate-based 3D framework K₅H₄{Ce₃(H₂O)₉[As₂W₂₁O₇₂(mal)₂]}·20H₂O (1) (mal = malic acid) has been synthesized by the metastable precursor [As₂W₁₉O₆₇(H₂O)]^14 −, which was further characterized by IR spectrum, thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. Structural analysis revealed that 1 consists of the organo-functionalized [As₂W₂₁O₇₂(mal)₂]^18 − units linked together by the Ce^3 + ions resulting in 3D network-like architecture. Magnetic property studies indicate that obvious antiferromagnetic interactions exist in three Ce^3 + ions.     

A new 3D pillared-layer porous framework with intersecting open channels in the Co/triazolate/carboxylate system: Synthesis,structure and magnetism

A new Co(II) coordination polymer, namely [Co₆(btc)₄(dtb)₂(H₂O)₃]_n (1) (H₃btc = 1,3,5-benzenetricarboxylic acid, dtb = 1,3-di-(1,2,4-triazole-4-yl)benzene), has been synthesized by combining the mixed ligands of H₃btc and dtb with Co(Ac)₂·4H₂O under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 feature a 3D open framework with intersecting channels based on Co-btc^3 − layers and btc^3 − and dtb pillars. The magnetic property of the complex has also been investigated at room temperature.     

A functionalized polyoxometalate by hexanuclear copper–amino acid coordination complexes

A new functionalized polyoxometalate by transition metal–amino acid coordination complexes, H₄[Na(H₂O)₂][Cu₆Na(gly)₈(H₂O)₂][BW₁₂O₄₀]₂ · 13H₂O (1) (gly = glycine) has been synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single crystal X-ray diffraction. Compound 1 possesses a 3D framework, which is built up of [BW₁₂O₄₀]⁵⁻ building blocks, hexanuclear [Cu₆Na(gly)₈] coordination clusters and Na⁺ ions. Furthermore, magnetic measurements show ferromagnetic interactions for compound 1.     

Three dimensional lanthanide-organic frameworks containing tetranuclear Ln (Ln = La,Nd) cluster secondary building blocks

The hydrothermal reactions of Ln₂O₃, o-phthalic acid (H₂L₁) and N,N’-Piperazine(bis-methylene phosphonic acid) hydrochloride (H₄L₂·HCl) yielded two three dimensional (3D) lanthanide-organic frameworks formulated as [Ln₄(L₁)₂(H₂L₂)₃(H₃L₂)₂]·18H₂O (Ln = La, 1; Nd, 2). Single-crystal X-ray diffraction revealed that they are isostructural. They feature 3D open framework structures containing rarely observed centrosymmetric tetranuclear lanthanide sub-building units (SBU). The photoluminescence property of 2 has been investigated, and it shows strong solid-emissions in the near-infrared region at room temperature.     

1D chain lanthanide coordination polymers with 6-hydroxynicotinic acid: Crystal structures and luminescent properties

Four new lanthanide coordination polymers {[Ln(HL)₂(H₂O)₅] · HL ·  H₂O}_n (Ln = Sm for 1, Eu for 2, Tb for 3 and Dy for 4) (H₂L = 6-hydroxynicotinic acid) have been synthesized and characterized by elemental analysis, FT-IR spectra and X-ray single-crystal diffraction. They all exhibit 1D chain structure, which are further linked via hydrogen bonds to form 3D supramolecular architecture. Luminescent properties of these lanthanide coordination polymers are studied.     

A new compound based on polyoxoniobates and three types of copper complexes

A new compound based on bi-capped Keggin polyoxoniobates and copper coordination complexes, with formula [Cu(en)₂][Cu(en)₂(H₂O)₂][Cu(en)₂(H₂O)]₂[H₄SiNb₁₂V₂O₄₂]·7H₂O (1) (en = ethylenediamine), was obtained under hydrothermal condition and characterized by single crystal X-ray diffraction, infrared spectrum (IR), powder X-ray diffraction (PXRD), Ultraviolet–visible spectroscopy (UV–vis) and electron spin resonance (ESR) analysis. Compound 1 has three different types of copper complexes in it. A [Cu(en)₂]^2 + and two [Cu(en)₂(H₂O)]^2 + fragments were supported by the polyoxoniobate to form a novel polyoxoniobate tri-supported coordination complex.     

Two organic–inorganic hybrid materials based on the penta-nuclear {MMn4} (M = W and Mo) heterometallic clusters and Schiff-base ligands

Two organic–inorganic hybrid compounds with the formula {[Mn^III(Salen)(H₂O)]₄MoO₄}·Cl₂·16H₂O (1) and {[Mn^III(Salen)(H₂O)]₄WO₄}·(CH₃COO)₂·11H₂O (2) (Salen = Di-[2-hydroxyl-3-methoxyl-benzaldehyde] ethylenediamine) have been synthesized and structurally characterized by IR, UV–vis spectroscopy, TG analysis and single crystal X-ray diffraction. Structural analysis revealed that compounds 1 and 2 consist of a [MoO₄]^2 − or [WO₄]^2 − building unit and four {[Mn^III(Salen)(H₂O)]⁺ metal–organic moieties, respectively. In the crystal structure, the [MoO₄]^2 − or [WO₄]^2 − tetrahedra coordinated with four Mn^III ions, resulting in the penta-nuclear heterometallic tetrahedra cluster compounds, which were rarely observed in the Mn-Salen system. Magnetic study revealed that there was antiferromagnetic coupling in the two compounds.     

Two 1-D Krebs-type heteropolyoxotungstates based on [X2W21O72Na(OH)2]13 − (X = SbIII,BiIII) units

By the one-pot self-assembly reaction of simple materials under acidic aqueous solution, two 1-D chain Krebs-type heteropolyoxometalates [H₂N(CH₃)₂]₂Na₁₁[X₂W₂₁NaO₇₂(OH)₂]·34H₂O (X = Sb^III for 1, Bi^III for 2) have been successfully synthesized and structurally characterized by elemental analysis, IR spectra, UV spectra, thermogravimetric (TG) analysis and X-ray single-crystal diffraction. The most prominent structural feature of 1 and 2 is that both display an interesting 1-D chain alignment constructed from Krebs-type [X₂W₂₁NaO₇₂(OH)₂]^13 − fragments connected by sharing four W–O–W connectors, which is for the first time observed in the polyoxometalate chemistry. Additionally, the electrochemical properties of 1 and 2 have been studied in 0.5 mol L^− 1 Na₂SO₄ + H₂SO₄ supporting electrolyte.