Structure and characterization of zero- to two-dimensional compounds built up of the sandwich-type clusters and transition-metal linkers

Five new heteropolyoxotungstates K₂Na₂Mn₂(H₂O)₁₂[Mn₂(H₂O)₁₀Mn₄(H₂O)₂(XW₉O₃₄)₂]·18H₂O (X=Ge, 1; X=Si, 2), Na₄[Mn₄(H₂O)₁₈Mn₄(H₂O)₂(XW₉O₃₄)₂]·22H₂O (X=Ge, 3; X=Si, 4) and K₃Na₅[Mn₂(H₂O)₆Mn₄(H₂O)₂(SiW₉O₃₄)₂]·23.5H₂O (5) have been obtained by the routine synthetic reactions in aqueous solution. In 1 and 2, two isolated Mn²⁺ ions are covalently linked to the sandwich-type polyoxoanions [Mn₄(H₂O)₂(B-α-XW₉O₃₄)₂]¹²⁻ (X=Ge or Si) by two μ₂-oxygen atoms resulting in the disupporting sandwich-type polyoxometalates (POMs). Compounds 3 and 4 are built from the disupporting sandwich-type polyoxoanions 1 and 2, linked by additional four Mn²⁺ ions to construct a 1D ladder-like chain-like structure, which is rarely observed in the POM chemistry. Compound 5 represents the first example of the 2D structure consisting of the sandwich-type polyoxoanion [Mn₄(H₂O)₂(SiW₉O₃₄)₂]¹²⁻ and the binuclear {Mn₂(H₂O)₆}⁴⁺ group. The magnetic studies of compounds 1, 4 and 5 indicate that the antiferromagnetic interactions are predominant in the three compounds between Mn(II) metal ions.     

Hydrothermal synthesis and structural characterization of three inorganic–organic composite sandwich-type phosphotungstates

Three inorganic–organic composite sandwich-type phosphotungstates [Ni(tepa)(H₂O)]₄H₂[Ni₄(H₂O)₂(α-B-PW₉O₃₄)₂]·8H₂O (1), (enH₂)₃[Ni₂(H₂O)₁₀][Ni₄(H₂O)₂(α-B-PW₉O₃₄)₂]·en·8H₂O (2) and (enH₂)₁₀[Mn₄(H₂O)₂(α-B-PW₉O₃₄)₂]₂·20H₂O (3) (tepa=tetraethylenepentamine and en=ethylenediamine) have been synthesized by the hydrothermal reaction of the trivacant Keggin polyoxoanion [α-A-PW₉O₃₄]⁹⁻ with Ni²⁺ or Mn²⁺ ions in the presence of tepa or en and structurally characterized by IR spectra, elemental analysis, thermogravimetric analysis and variable temperature magnetic susceptibility. X-ray crystallographic analyses indicate that they all contain the classical tetra-M sandwiched polyoxoanions [M₄(H₂O)₂(α-B-PW₉O₃₄)₂]¹⁰⁻ (M=Ni²⁺ or Mn²⁺) and nickel-organoamine cations or organoamine cations work as the charge balance ions. The tetra-M clusters in 1, 2 and 3 exhibit the familiar structural type of a β-junction at the sites of metal incorporation. The study of magnetic property of 1 is indicative of a typical ferromagnetic coupling between Ni²⁺ cations.     

Assemblies based on the directing effect of non-classical W18 anionic clusters and the rod-like trans-1,2-di-(4-pyridyl)-ethylen (bpe)

Two polyoxometalate (POM) supramolecular assemblies based on W₁₈ clusters and the rigid organic trans-1,2-di-(4-pyridyl)-ethylen (bpe) have been synthesized and fully characterized, namely (H₂bpe)3.5H₂[SbW₁₈O₆₀]·5H₂O (1), and (H₂bpe)5[Ni₄(AsW₉O₃₄)₂(H₂O)₂]·3H2O (2). Compounds 1-2 are formed from organic bpe cations and different polytungstate anions: pseudo-Dawson-type [SbW₁₈O₆₀]⁹⁻ in 1 and sandwich-type [Ni₄(H₂O)₂(AsW₉O₃₄)₂]¹⁰⁻ in 2. Both of compounds 1-2 crystallize in a low-symmetrical space group of P-1 and consist of a complicated supramolecular network based on non-covalent intermolecular weak interactions, including hydrogen bonding and π···π stacking. The multipoint hydrogen bonding interactions constitute the structural feature in two supramolecular frameworks. The UV-vis, fluorescence and electrochemistry properties are also studied.     

Hydrothermal Syntheses and Structural Characterization of Two 3-D Supramolecular Networks Constructed from Tetra-CoII Sandwiched Polyoxometalates

Two Co₄-substituted sandwich-type polyoxometalates (H₂en)₉[Co₄(H₂O)₂(PW₉O₃₄)₂]{[Co(H₂O)₄][Co₄(H₂O)₂(PW₉O₃₄)₂]}·18H₂O (1) and (H₂en)₅[Co₄(H₂O)₂(H₃GeW₉O₃₄)₂]{[Co(H₂O)₄]₂[Co₄(H₂O)₂(H₂GeW₉O₃₄)₂]}·16H₂O (2) (en = ethylenediamine) have been hydrothermally synthesized and characterized by IR spectra, elemental analyses, thermogravimetric analyses, powder X-ray diffraction and single-crystal X-ray diffraction. Single-crystal structure analysis reveals that the molecules of 1 and 2 contain two Co₄-substituted sandwich-type polyoxoanions. This type of a molecular unit containing double polyoxoanions is very rare. From the viewpoint of supramolecular chemistry, the sandwich-type polyoxoanions in 1 and 2 can be further extended to 3-D frameworks via extensive hydrogen-bonding interactions.     

A novel 2D layer structure constructed from sandwich-type transition metal substituted tungstates and nickel coordination fragments: {[Ni(enMe)2]2[Ni(enMe)2(H2O)]2[As2W18Ni4(enMe)2O68]}·2H3O·2H2O

A novel polyoxometalate {[Ni(enMe)₂]₂[Ni(enMe)₂(H₂O)]₂[As₂W₁₈Ni₄(enMe)₂O₆₈]}·2H₃O·2H₂O (1) (enMe = 1,2-propylenediamine) has been synthesized and characterized, which is the first high-dimensional structure constructed from sandwich-type transition metal substituted tungstates and transition metal coordination groups.     

Dinuclear nickel(II) complexes with Schiff base ligands: syntheses, structures and bio-relevant catalytic activities

Three Ni(II) complexes of cresol-based Schiff-base ligands, namely [Ni₂(L¹)(NCS)₃(H₂O)₂], (1) [Ni₂(L²)(CH₃COO)(NCS)₂(H₂O)] (2) and [Ni₂(L³)(NCS)₃] (3), (where L¹ = 2,6-bis(N-ethylpyrrolidineiminomethyl)-4-methylphenolato, L² = 2,6-bis(N-ethylpiperidineiminomethyl)-4-methylphenolato and L³ = 2,6-bis{N-ethyl-N-(3-hydroxypropyl iminomethyl)}-4-methylphenolato), have been synthesized and structurally characterized by X-ray single-crystal diffraction in addition to routine physicochemical techniques. Density functional theory calculations have been performed to understand the nature of the electronic spectra of the complexes. Complexes 1?C3 when reacted with 4-nitrophenyl phosphate in 50:50 acetonitrile?Cwater medium promote the cleavage of the O?CP bond to form p-nitrophenol and smoothly convert 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) either in MeOH or in MeCN medium. Phosphatase- and catecholase-like activities were monitored by UV?Cvis spectrophotometry and the Michaelis?CMenten equation was applied to rationalize all the kinetic parameters. Upon treatment with urea, complexes 1 and 2 give rise to [Ni₂(L¹)(NCS)₂(NCO)(H₂O)₂] (1??) and [Ni₂(L²)(CH₃COO)(NCO)(NCS)(H₂O)] (2??) derivatives, respectively, whereas 3 remains unaltered under same reaction conditions.     

The chain-shaped coordination polymers based on the bowl-like Ln18Ni24(23.5) clusters exhibiting favorable low-field magnetocaloric effect

The design of assembling high-nuclearity transition-lanthanide (3d-4f) clusters along with excellent magnetocaloric effect (MCE) is one of the most prominent fields but is extremely challenging. Herein, two heterometallic metal coordination polymers are constructed via the “carbonate-template” method, formulated as {[Gd₁₈Ni₂₄(IDA)₂₂(CO₃)₇(μ₃-OH)₃₂(μ₂-OH)₃(H₂O)₅Cl]·Cl₈·(H₂O)₁₄}_n and {[Eu₁₈Ni_23.5(IDA)₂₂(CO₃)₇(μ₃-OH)₃₂(H₂O)₅(IN)(CH₃COO)₂(NH₂CH₂COO)Cl]·Cl₆·(H₂O)₁₇}_n [abbreviated as 1-(Gd₁₈Ni₂₄)_n and 2-(Eu₁₈Ni_23.5)_n respectively; H₂IDA = iminodiacetic acid; HIN = isonicotinic acid]. Concerning the structures, compounds 1-(Gd₁₈Ni₂₄)_n and 2-(Eu₁₈Ni_23.5)_n both feature the one-dimensional (1D) chain-like structure which is rarely reported in high-nuclearity metal complexes. Meanwhile, the large presences of Gd³⁺ ions in compound 1-(Gd₁₈Ni₂₄)_n are conducive to the fantastic MCE, and the value of −∆S_m is 35.30 J kg⁻¹ K⁻¹ at 3.0 K and ∆H = 7.0 T. And more significantly, compound 1-(Gd₁₈Ni₂₄)_n shows the large low-field magnetic entropy change (−∆S_m = 20.95 J kg⁻¹ K⁻¹ at 2.0 K and ∆H = 2.0 T) among the published 3d-4f mixed metal clusters.     

Two 3D networks based on sandwich-type polyoxometalate units linked by Sr-O clusters: Synthesis, structure, and magnetic property

Two 3D hybrid sandwich-type polyoxometalates, [{Sr(H₂O)₅Sr(H₂O)₆Sr_0.5(H₂O)₇}₂Mn₄(H₂O)₂(α-PW₉O₃₄)₂]·6H₂O (1) and [{Sr(H₂O)₆[Sr(H₂O)₈]₂Sr(H₂O)₄}₂Mn₄(H₂O)₂(αββα-P₂W₁₅O₅₆)₂]·5H₂O (2), have been obtained by the routine synthetic reactions in aqueous solution and characterized by IR, elemental analysis, thermal analysis, and X-ray single-crystal diffraction. The 3D hybrid framework of 1 and 2 are built by tetra-Mn^II substituted sandwich-type polyoxotungstates modified by fourteen Sr(H₂O)_x (x=4-8) units acting as bridges, forming centrosymmetric sandwich structures. The magnetic property of compound 1 has been studied by measuring its magnetic susceptibility in the temperature range of 2-300 K, which indicates predominant ferromagnetic interactions between the Mn^II-O-Mn^II bridge unit. Additionally, the electrochemical behaviours have been detected on solid bulk modified carbon paste electrodes of compounds (CPEs) and three redox couples are detected.     

Temperature-Dependent Organic Functionalization of {Ni6PW9} Species: from Isolated Clusters to 1D Chain

Four new hexa-nickel(II)-substituted Keggin-type tungstophosphates [Ni₆(μ₃-OH)₃(oeen)₃(H₂O)₃(B-α-PW₉O₃₄)]·6H₂O (1, oeen = N-(2-hydroxyethyl)enediamine), [Ni₆(μ₃-OH)₃(oeen)₃(H₂O)₄(B-α-PW₉O₃₄)]₂·13H₂O (2), [Ni₆(μ₃-OH)₃(oeen)₂(tran)(H₂O)₃(B-α-PW₉O₃₄)]·3H₂O (3, tran = 1,4,7-triazonane) and [Ni₆(μ₃-OH)₃(oeen)₂(tran)(H₂O)₂(B-α-PW₉O₃₄)]·6H₂O (4) have hydrothermally made by controlling their reaction temperatures. 1–4 have been characterized by elemental analyses, IR spectra, powder X-ray diffraction, thermogravimetric analyses and single-crystal X-ray diffraction, respectively. Structural analyses reveal that they consist of {Ni₆(μ₃-OH)₃(H₂O) _n }⁹⁺ cores and B-α-PW₉O₃₄ (PW₉) units, and further are stabilized by organic neutral oeen/tran molecules. 1–3 are isolated clusters while 4 is the 1D chain structure. It should be noted that the tran molecules in 3 and 4 are derived from the oeen molecules in the starting materials.     

Four novel linear trinuclear assemblies containing bridging triazole ligands. Crystal structure,magnetic, semiconducting and fluorescent properties

Four homotrinuclear linear coordination compounds with bridging ligand of (m-phenol)-1,2,4-triazole, [Mn₃(L)₆(H₂O)₆](ClO₄)₆ (1), [Ni₃(L)₆(H₂O)₆](BF₄)₆·4DMF (2), [Cd₃(L)₆(H₂O)₆](ClO₄)₆· 2H₂O·2DMF·2EtOH (3), [Zn₃(L)₈(H₂O)₄](BF₄)₄(SiF₆)·2EtOH·12H₂O (4), have been synthesized and structurally determined. The structures consist of three metal ions in linear arrangements, linked to each other by two pairs of three N1, N2 bridging triazole ligands. The negative value of J suggests that antiferromagnetic interaction exists in 1. Green fluorescence of 2 and 4 with emissions at 518 nm for 2 and 524 for 4 is possibly assigned to LMCT. The energy gaps of the compounds 2 and 4 are 1.82 and 1.97 eV, respectively, which suggests that the two materials behave as semiconductors.     

Sandwich-type polyoxotungstate hybrids decorated by nickel-aromatic amine complexes

Three new sandwich-type polyoxotungstates (POTs) decorated by nickel-2,2′-bpy complexes [{Ni(2,2′-bpy)₂(H₂O)}₂{Ni(2,2′-bpy)}₂ {Ni₄(H₂O)₂(B-α-XW₉O₃₄)₂}]ⁿ⁻ (X=P^V, n=4 for 1; X=As^V, n=4 for 2; X=Ge^IV, n=4 for 3) (2,2′-bpy=2,2′-bipyridine) were successfully synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction, and magnetic properties. Single-crystal structural analyses indicate that 1 and 2 are isostructural and both crystallize in the monoclinic space group C2/c, whereas 3 belongs to the triclinic space group . To our knowledge, 1, 2 and 3 represent rare examples of the organic-inorganic hybrid sandwich-type polyoxometalates functionalized by multiple nickel-aromatic amine complexes. Magnetic measurements of 1 exhibit the presence of ferromagnetic interactions within the rhombic tetranuclear-Ni^II cluster.     

Crystal structure, spectroscopy and magnetism of trinuclear nickel(II), cobalt(II) complexes and their solid solution

Four new complexes [Ni₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (1), [Co₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (2), [Ni₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (3), [Co₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (4) (L = 4-amino-3,5-dimethanyl-1,2,4-triazole) were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complex 1 and 2 are isomorphous; complex 3 and 4 are isomorphous. Four complexes all consist of the linear trinuclear cations ([M₃(μ-L)₆(H₂O)₆]⁶⁺ (M = Ni,Co) for 1 and 2; [M₃(μ-L)₆(H₂O)₄(CH₃OH)₂]⁶⁺ (M = Ni,Co) for 3 and 4), NO₃⁻ anions and crystallized water molecules. In the trinuclear cations, the central M(II) ions and two terminal M(II) ions are bridged by three triazole ligands. Other eleven solid solution compounds which are isomorphous with complex 3 and 4 were obtained by using different ratio of Ni(II) and Co(II) ions as reactants and ICP result indicates that ligand L has higher selectivity of Ni(II) ions than that of Co(II) ions. The magnetic analysis was carried out by using the isotropic spin Hamiltonian ? = −2J(?₁?₂ + ?₂?₃) (for complexes 1 and 3) and simultaneously considering the temperature dependent g factor (for complexes 2 and 4). Both the UV-Vis spectra and the magnetic properties of the solid solutions can be altered systematically by adjusting the Co(II)/Ni(II) ratio.     

A new [Ni4] distorted cubane assembly on four solvent derived μ3-OMe corners: Solvent dependent formation and cleavage of exogenous bridges

A new Ni₄ distorted cubane complex [Ni₄(μ₃-OMe)₄Q₄(MeOH)₄] (1) (where Q⁻ is the anion of 8-quinolinol) is obtained from the reaction of NaQ with Ni(OAc)₂ · 4H₂O in refluxing MeOH via solvent derived μ₃-OMe assisted self-assembly of four nickel(II) centres. The periphery of [Ni₄(OMe)₄] cubane is covered by four Q⁻ and four MeOH molecules. This methanol specific reaction is not supported in solvent glycinol (Hgl; NH₂(CH₂)₂OH), an amine substituted ethanol, producing monomeric [NiQ₂(Hgl)₂] · 2H₂O (2 · 2H₂O) instead and is able to cleave 1 to yield 2 · 2H₂O. The cryomagnetic susceptibility data of powdered 1 can be modeled by a two J equation yielding J₁ = −1.8(1) cm⁻¹, J₂ = 3.9(1) cm⁻¹ and g = 2.24.     

A mononuclear complex and a cubane cluster from the initial use of 2-(hydroxymethyl)pyridine in nickel(II) carboxylate chemistry

The reactions of 2-(hydromethyl)pyridine, hmpH, with Ni(O₂CMe)₂·4H₂O in H₂O, in the absence of counterions, have been investigated. The synthetic study has led to the two new complexes [Ni(O₂CMe)₂(hmpH)₂] (1) and [Ni₄(O₂CMe)₄(hmp)₄(H₂O)₂] (2). Complex 1 can also be transformed into 2 by reacting with an excess of NaOH in H₂O. The structures of 1 and 2·2.25H₂O·0.5(1,4-dioxane) have been solved by single-crystal, X-ray crystallography. The octahedral Ni^II center in centrosymmetric 1 is coordinated by two 1.10 (Harris notation) MeCO₂⁻ groups and two N,O-chelating (1.11) hpmH ligands. The tetranuclear cluster molecule of 2·2.25H₂O·0.5(1,4-dioxane) possesses a distorted cubane {Ni₄(μ₃-OR′)₄}⁴⁺ core [R′ = (2-pyridyl)CH₂–] with the Ni^II ions and the oxygen atoms from the 3.31 hmp⁻ ligands occupying alternate vertices of the cube. Two 2.11 MeCO₂⁻ groups cap two opposite faces of the cube, while two 1.10 MeCO₂⁻ ions and two aqua ligands complete the octahedral coordination sphere of the metal centers. Characteristic IR bands for the two complexes are discussed in terms of the nature of bonding and the structures of the two complexes. The variable-temperature magnetic properties of 2 have been modeled with two J values, and reveal antiferromagnetic exchange interactions between the four Ni^II ions to give a diamagnetic ground state.     

Two New One-Dimensional Chain-Like Compounds Constructed from the Sandwich-Type Polyoxotungstate Clusters

Two new one-dimensional chain-like compounds, K₄Na₄[Mn₂(H₂O)₈Mn₄(H₂O)₂(GeW₉O₃₄)₂] · 20.5H₂O (1) and K₂Na₄Cu₂(H₂O)₁₂[Cu(H₂O)₂Cu₄(H₂O)₂(SiW₉O₃₄)₂] · 15H₂O (2), constructed from the sandwich-type clusters, have been obtained by the routine synthetic reactions in aqueous solutions, and their structures were determined by X-ray single crystal diffraction analysis. The crystal data is following: for 1, space group, monoclinic, P _21/n, a = 16.693(3) Å, b = 14.935(3) Å, c = 20.090(4) Å, β = 92.23(3)°, V = 5004.7(17) ų, Z = 2; For 2, space group, triclinic, P _?1, a = 11.744(2) Å, b = 13.415(3) Å, c = 17.609(4) Å, α = 73.08(3)°, β = 82.68(3)°, γ = 65.18(3)°, V = 2409.1(8) ų, Z = 1. The crystal structure of 1 shows a 1D ladder-like chain, built up of the sandwich anions [Mn₄(H₂O)₂(GeW₉O₃₄)₂]^12? and the Mn²⁺ ions. Compound 2 is a polymeric chain, composed of the Cu-substituted sandwich-type anions [Cu₄(H₂O)₂(SiW₉O₃₄)₂]^12? linked by the Cu(H₂O)₄ clusters. These extended materials based on the sandwich-type polyoxoanions are rarely reported in the POM chemistry.     

Syntheses and study on nickel and copper complexes with 1,3,5-benzenetricarboxylic acid. Crystal and molecular structure of [Cu3(mdpta)3(btc)](ClO4)3 · 4H2O

Nickel and copper complexes containing 1,3,5-benzenetricarboxylic acid, with a combination of selected N-donor ligands and Schiff bases, of the composition Ni₃(bimz)₆(btc)₂ · 12H₂O (1), Ni₃(btz)₉(btc)₂ · 12H₂O (2), Ni₂(L₁)(btc) · 7H₂O (3), Ni₃(L₂)₂(Hbtc) · 9H₂O (4), Ni₂(L₃)(btc) · 4H₂O (5), Cu₂(L₄)(btc) · 7H₂O (6), [Cu₃(pmdien)₃(btc)](ClO₄)₃ · 6H₂O (7) and [Cu₃(mdpta)₃(btc)](ClO₄)₃ · 4H₂O (8); H₃btc = 1,3,5-benzenetricarboxylic acid, bimz = benzimidazole, btz = 1,2,3-benztriazole, L₁ = 2-[(phenylimino)methyl]phenol, L₂ = N,N′-bis-(salicylidene)propylenediamine, L₃ = 2-{[(2-nitrophenyl)methylene]amino}phenol, L₄ = 2-[(4-methoxy-phenylimino)methyl]phenol, pmdien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, mdpta = N,N-bis-(3-aminopropyl)methylamine, have been synthesized. The complexes have been studied by elemental analysis, IR, UV–Vis spectroscopies, magnetochemical and conductivity measurements and selected compounds also by thermal analysis. The crystal and molecular structure of complex 8 was solved. The complex is trinuclear with btc³⁻-bridge. The coordination polyhedron around each copper atom can be described as a distorted square with a CuON₃ chromophore formed by one oxygen atom of carboxylate and three nitrogen atoms of mdpta. The magnetic properties of 8 have been studied in the 1.8–300 K temperature range revealing a very weak antiferromagnetic exchange interaction with J = −0.56 cm⁻¹ for g = 2.13(9). The antimicrobial activities against selected strains of bacteria were evaluated. It was found that only complex 5 is able to inhibit the growth of Staphylococcus strains.     

Syntheses,characterization, and magnetic properties of two 3D frl topological frameworks constructed from nickel diphosphonates

Two 3D open-framework nickel diphosphonates, [Ni₃(H₂zdn)₂(bpe)₂]·4H₂O (1) and [Ni₃(H₂zdn)₂(bpy)₂]·bpy·4H₂O (2) (H₅zdn = zoledronic acid, bpe = trans-4,4-vinylenedipyridine, bpy = 4,4′-dipyridyl), have been prepared and structurally characterized. In complex 1, the metal centers are linked by zoledronate ligands to generate a 2D layer, containing 14- and 24-membered rings. These 2D layers are further pillared by the bpe ligands into a 3D network structure with cylindrical channels. Magnetic susceptibility measurements reveal ferrimagnetism at T _c = 3.8 and 4.4 K for complexes 1 and 2, respectively.     

Synthesis,crystal structures,adsorption and fluorescence properties of coordination polymers based on a semirigid octadentate ligand

Using an octadentate ligand, namely tetrakis[(3,5-dicarboxyphenoxy)methyl] methane (H₈L), four coordination polymers, [Ni₃L(OH)₂(H₂O)₂][NH₂(CH₃)₂]₄·5H₂O (1), [Co₄L(H₂O)₄]·9H₂O (2), [Zn₄L(H₂O)₄]·DMF·11H₂O (3) and [Li₄(H₄L)(H₂O)₄] (4) (DMF = N,N-dimethylformamide), have been solvothermally synthesized and structurally characterized by X-ray crystallography. Complex 1 is an anionic three-dimensional open framework built from tricluster {Ni₃(COOR)₈} and square planar L ligands to give a uninodal 6-connected pcu network. Complexes 2 and 3 are isostructural, possessing a non-interpenetrated three-dimensional network with rare (4,8)-connected scu topology. Complex 4 consists of 4-connecting {Li₂(COOR)₄} clusters which form a 2D Shubnikov tetragonal plane net with sql topology. Complexes 1–3 all have large solvent accessible voids, but only complex 3 possesses permanent porosity as confirmed by N₂, H₂, CO₂ and CH₄ gas adsorption measurements. In addition, complex 3 shows strong photoluminescent emissions at room temperature with a peak at 365 nm, owing to a ligand-centered excited state. The emission intensities of 3 varied upon contact with different solvents or analytes.     

Synthesis,characterization and antimicrobial activity of Ni(II) and Zn(II) complexes with N′,N′-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide. Crystal structures of two highly solvated bimetallic complexes of Ni(II)

The bimetallic [Ni₂(H₂L2)₂](ClO₄)₄ (1), [Ni₂(HL2)(H₂L2)](ClO₄)₃ (2) and [Zn₂(H₂L2)₂](BF₄)₄ (3) complexes (H₂L2 = N′,N′²-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide) were synthesized and characterized. The structure of complexes (1) and (2) was established by X-ray analysis. NMR spectroscopy was used for the characterization of complex (3). The complexes (1) and (2) were obtained from the same synthetic reaction and two crystal types of these complexes have been isolated during the fractional crystallization process.     

Molecular and polymeric uranyl and thorium hybrid materials featuring methyl substituted pyrazole dicarboxylates and heterocyclic 1,3-diketones

A series of seven novel f-element bearing hybrid materials have been prepared from either methyl substituted 3,4 and 4,5-pyrazoledicarboxylic acids, or heterocyclic 1,3- diketonate ligands using hydrothermal conditions. Compounds 1, [UO₂(C₆H₄N₂O₄)₂(H₂O)], and 3, [Th(C₆H₄N₂O₄)₄(H₂O)₅]·H₂O feature 1-Methyl-1H-pyrazole-3,4-dicarboxylate ligands (SVI-COOH 3,4), whereas 2, [UO₂(C₆H₄N₂O₄)₂(H₂O)], and 4, [Th(C₆H₅N₂O₄)(OH)(H₂O)₆]₂·2(C₆H₅N₂O₄)·3H₂O feature 1-Methyl-1H-pyrazole-4,5-dicarboxylate moieties (SVI-COOH 4,5). Compounds 5, [UO₂(C₁₃H₁₅N₄O₂)₂(H₂O)]·2H₂O and 6, [UO₂(C₁₁H₁₁N₄O₂)₂(H₂O)]·4.5H₂O feature 1,3-bis(4-N¹-methyl-pyrazolyl)propane-1,3-dione and 1,3-bis(4-N¹,3-dimethyl-pyrazolyl)propane-1,3-dione respectively, whereas the heterometallic 7, [UO₂(C₁₁H₁₁N₄O₂)₂(CuCl₂)(H₂O)]·2H₂O is formed by using 6 as a metalloligand starting material. Single crystal X-ray diffraction indicates that all coordination to either [UO₂]²⁺ or Th(IV) metal centers is through O-donation as anticipated. Room temperature, solid-state luminescence studies indicate characteristic uranyl emissive behavior for 1 and 2, whereas those for 5 and 6 are weak and poorly resolved.