First hexanuclear manganese(II) μ6-Cl centered carboxylate anion: Synthesis,structure and magnetic properties

Reaction of manganese(II) polymer [Mn₅Cl(OH)(Piv)₈(MeCN)(HPiv)(H₂O)]_n (1, HPiv is pivalic acid) and 2-benzoylpyridine (L) in MeCN produces the ionic complex [Mn₃(Piv)₅L₂(MeCN)]⁺[Mn₆Cl(Piv)₁₂]⁻ · MeCN (3) containing the unusual hexanuclear {Mn₆(μ₆-Cl)} anion. An analogous anion was also observed in the complex [Mn₆Cl(Piv)₁₂]⁻(NEt₄)⁺ · 5MeCN (4) prepared by the reaction of the polymer [Mn(Piv)₂(EtOH)]_n (2) with NEt₄Cl in MeCN. Complexes 3 and 4 were characterized by the X-ray diffraction and magnetic susceptibility.     

1D nickel(II) coordination polymer with pyrimidine and pivalate bridges: Synthesis,structure and magnetic properties

New 1D polymeric compound [Ni₂(μ-OH₂)(μ-Piv)₂(Piv)₂(μ-pym)(η¹-pym)₂]_n (3, Piv is an anion of pivalic acid) was synthesized upon the reaction of the nickel(II) pivalate complex Ni₉(OH)₆(Piv)₁₂(HPiv)₄ (3) and pyrimidine (pym) in MeCN. Complex 3 was characterized by the X-ray diffraction study and magnetic measurements. It is shown that neighboring Ni sites in the 1D metal chain in 3 are coupled by weak antiferromagnetic interactions with two exchange parameters of J₁ = –3.1 and J₂ = –1.2 cm^–1.     

Construction of three new mixed-ligand Zn(II) coordination polymers based on nitrogen-containing heterotopic ligands and carboxylate co-ligands

Reactions of Zn(II) salts, presynthesized 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and various carboxylate ligands result to three new coordination polymers (CPs), namely, [Zn₂[(IPT)₂(ox)]}_n (H₂ox = oxalic acid, 1), [Zn₂(IPT)₂(mNBDC)]_n (H₂mNBDC = 5-nitroisophthalic acid, 2), and [Zn₂(IPT)(CA)(H₂O)]_n (H₃CA = citric acid, 3). Compound 1 can be seen as constructed from 2D [Zn(IPT)]_n layers with (6,3) topology and pillared by ox^2 −. It is a 3D (3,4)-connected framework with InS topology. Compound 2 has 2D bilayer structure based on 2D [Zn(IPT)]_n single layer and mNBDC^2 − linkers. Compound 3 is a 3D pillar-layer framework built by Zn–CA bilayers and IPT⁻ pillars. The results showed that the coordination modes, configurations of IPT⁻, and the structure of carboxylate co-ligands have great influence on the structures of the final network. The choice of carboxylate can decide the result of CPs in Zn–IPT chains/net subunits plus carboxyl linkers or Zn–carboxylate chains/net subunits plus IPT⁻ linkers. The thermal stabilities and luminescent properties of selected compounds have also been studied.     

Three d10 coordination polymers based on rigid ligands with flexible functional groups: Syntheses,structures and luminescence

Three coordination polymers, namely, {[Zn(L)(BPY)]·DMF·H₂O}_n (1), {[Zn(L)(TPY)]·0.5H₂BDC·H₂O}_n (2), {[Cd(L)(H₂O)₂]·DMF}_n (3), have been synthesized based on a rigid linear carboxylate ligand (H₂L = 2′,5′-dimethoxy-[1,1′:4′,1″-terphenyl]-4,4″-dicarboxylic acid) and different lengths of pyridine ligands (TPY = 4,3′:5′,4″-terpyridine; BPY = 4,4′-bipyridine). These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Complex 1 is a 6-connected 3-fold interpenetrating pcu net with point symbol {4¹² ∙ 6³}, 2 and 3 can be simplified as 4-connected sql nets with point symbol {4⁴ ∙ 6²}. In addition, their photoluminescent properties are also investigated in detail.     

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu₂(IPT)(SO₄)(OH)(H₂O)]·H₂O}_n (HIPT = 5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd₂(IPT)(NPA)(OH)]·H₂O}_n (H₂NPA = 5-nitroisophthalic acid, 2), and {[Zn₂(IPT)(IDC)(H₂O)]·3H₂O}_n (H₃IDC = 1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu₂(IPT)(SO₄)(OH)]_n secondary building blocks and IPT⁻ linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA^2 − pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]_n chains and binuclear Zn₂(IPT)₂ rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions at room temperature.     

Synthesis and cytotoxicity of a ruthenium nitrosyl nitric oxide donor with isonicotinic acid and a cell penetrating peptide

The syntheses and properties of trans-[Ru(NH₃)₄(L)(NO)](BF₄)₃ (L = isonicotinic acid (inaH) (I) or ina-Tat48–60 (II)) are described. Tat48–60, a cell penetrating peptide fragment of the Tat regulatory protein of the HIV virus, was linked to the ruthenium nitrosyl through inaH. I and II release NO after reduction forming trans-[Ru(NH₃)₄(L)(H₂O)]^3 +. The IC₅₀ values against B16-F10 melanoma cells of I and II (21 μmol L^− 1 and 23 μmol L^− 1, respectively) are close to that of the commercially available cisplatin (33 μmol L^− 1) and smaller than similar complexes. The cytotoxicity is assigned to the NO released from I and II.     

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.     

Synthesis,structure, stability and DNA cleavage activities of three Cr(III) complexes with salicylate and ammonium ligands

Complexes [Cr(III)(SA)(en)₂]⁺ (1), [Cr(III)(SA)(DETA)(H₂O)]⁺ (2) and [Cr(III)(SA)(TETA)]⁺ (3) were synthesized (H₂SA = salicylic acid, en = ethylenediamine, DETA = diethylenetriamine, TETA = triethylenetetramine). Kinetics studies show that 2 is the most instable one among these complexes. In addition, only 2 is found to be a very efficient catalyst of the cleavage of PBR322 DNA in the absence of any added cofactor. The degradation rate from supercoiled form to nicked form was 1.05 ± 0.081 h^− 1 (10^− 5 M) at pH 7.4 and 37 °C. Thiobarbituric acid-reactive substances assay shows 2 fail to produce OH causing any degradation of deoxyribose ring even in the presence of ascorbic acid. Ethidium bromide displacement assay suggests that only 2 can kick out EB from the groove of DNA. The interaction with DNA causes a blue shift of the d → d transition spectra of 2.     

Binuclear cyano-bridged complex derived from [MnIII(salpn)] and [FeIII(CN)6]: Synthesis,structure and magnetic properties

The reaction of the neutral [Mn(salpn)C(CN)₃(H₂O)] (salpn^2 − = N,N^′-1,3-propylenebis(salicylideneiminato) dianion) with [Fe^III(CN)₆]^3 − in the presence of strong oxidizer (NH₄)₂S₂O₈ yields a binuclear anion complex [NH₃CH₂CH₂CH₂NH₃]^2 +{[Mn^III(salpn)(H₂O)][Fe^III(CN)₆]}^2 − (1). Its structure, DC and AC susceptibility have been studied. Frequency dependence of the AC susceptibility characteristic for single-molecule magnets has been found.     

Copper(II) azide complexes of [Cu(acac)(N3)(dpyam)] and [Cu(μ-N3-κN1)(C2N3-κN1)(dpyam)]2: Synthesis,crystal structure and magnetism

Two new compounds, [Cu(acac)(N₃)(dpyam)] (1), (acac = acetylacetonate; dpyam = di-2-pyridylamine) and [Cu(μ-N₃-κ^N1)(C₂N₃- κ^N1) (dpyam)]₂ (2), have been synthesized and characterized by single-crystal X-ray diffraction and magnetic analyses. Compound 1 is a mononuclear compound in which each of two independent Cu(II) ions is penta-coordinated with a distorted square pyramidal geometry with distortion parameters τ = 0.21 and 0.16. In contrast, compound 2 is an azido-bridged dinuclear compound with monodentate dicyanamide anions and the Cu(II) ions display a distorted trigonal bipyramidal geometry with τ = 0.73 and end-on azido bridges providing an equatorial–axial position between the metal ions. The EPR spectra of powdered samples for 1 and 2 have also been investigated. Magnetic susceptibility measurements of compound 2 reveal a very weak ferromagnetic interaction between the Cu(II) ions with a J value of +5.8 cm⁻¹.     

Hydrothermal syntheses and characterization of a series of mixed-ligand luminescent CdII frameworks with novel 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate ligand and benzenedicarboxylate isomers

Under similar hydrothermal synthetic conditions using a novel flexible ligand 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetonitrile (PPAN), benzenedicarboxylate isomers (H₂pa = phthalate, H₂ip = isophthalate, and H₂tp = terephthalate) and Cadmium(II) acetate, three novel mixed-ligand Cd(II) coordination polymers {[Cd₂(PPAA)₂(μ-pa)(H₂O)]·2H₂O}_n (1), {[Cd₄(PPAA)₄ (μ₄-ip)₂]·2H₂O}_n (2) and {[Cd₂(PPAA)₂(μ-tp)]·2H₂O}_n (3) (PPAA⁻ = 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate) have been isolated, in 1–3 PPAN, and are also hydrolyzed into a novel PPAA⁻ ligand. Complex 1 is a 1D coordination polymer in which the tetra-nuclear [Cd₄(PPAA)₄]^4 + structural units are extended by tri-dentate μ-pa^2 − ligands. Complex 2 contains binuclear [Cd₂(PPAA)₂]^4 + structural units, which are extended by four tetra-dentate μ₄-ip^2 − ligands to link eight neighboring binuclear [Cd₂(PPAA)₂]^4 + units ultimately forming a 2D layered framework, while complex 3 contains 1D double chain containing [Cd(PPAA)]_n cation structural units, which are further extended by tetradentate μ-tp^2 − ligands to form a new 2D layered framework. All the complexes have been investigated by elemental analysis, FT-IR, thermal analysis and fluorescence characterization. The flexible coordination modes of PPAA⁻ are also briefly analyzed. The flexible coordination modes of PPAA⁻ and benzenedicarboxylate isomers also reveal great potential in the construction of these novel mixed-ligand luminescent frameworks with diverse structural motifs and unique functional properties.     

Synthesis,crystal structure and magnetic properties of a new cyanide-bridged mixed-valence copper(I)/copper(II) clathrate

A unique cyanide-bridge mixed-valence Cu^I/Cu^II clathrate of formula [Cu^I₂(CN)₃][{Cu^II(tren)}₂(μ-CN)](CF₃SO₃)₂ [tren = tris(2-aminoethyl)amine] containing cyanide-bridged [{Cu^II(tren)}₂(μ-CN)]^3 + binuclear cations stacked between anionic honeycomb layered copper(I) cyanide networks, was synthesized and structurally characterized by single crystal X-ray diffraction. Variable-temperature magnetic susceptibility studies showed that the cyanide bridge mediates a strong antiferromagnetic interaction between the copper(II) centers (J = − 160 cm^− 1, the spin Hamiltonian being defined as H = −J S_A⋅S_B).     

A lead(II)-orotate coordination polymer with a new coordination mode: Synthesis,structure and luminescent property

A lead(II) orotate complex [Pb(HOr)(H₂O)]_n (1), (H₃Or = orotic acid) was synthesized under hydrothermal condition and characterized by X-ray diffraction, IR, solid-state photoluminescence and thermogravimetric analysis. Lead atom in 1 is in a holodirected eight-coordinated polyhedron and the orotate ligand exhibits a new and unique hexametallic coordination mode. The lead complex shows a 6,6-connected (4⁸, 6⁶, 8)(4¹³, 6²) topology. The complex exhibits photoluminescence at 546 nm (λ_ex = 350 nm).     

Structural characterization of ferromagnetic bridged-acetato and -dichlorido copper(II) complexes based on bicompartmental 4-t-butylphenol

The reaction of Cu(II) salts with 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-t-butylphenol (L^t-Bu-OH) afforded two bridged-phenoxido/hydroxido complexes. The dinuclear bridged acetate species [Cu₂(μ-L^t-Bu-O)(μ-CH₃COO)](PF₆)₂ (1) and the 1D polymeric doubly-bridged-chlorido {[Cu₂(μ-L^t-Bu-OH)(μ-Cl)₂](ClO₄)₂·4H₂O}_n (2). The two complexes were structurally characterized. Both complexes revealed ferromagnetic interactions; moderate in complex 1 (J = + 30.8 cm^− 1) and very weak (J = + 2.25 cm⁻¹) in 2.     

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 new luminescent Cd(II)/Zn(II) metal–organic frameworks for exceptionally selective detection of picric acid explosives

Two new coordination polymers, {[Cd(BIDPT)(oba)]·0.5H₂O}_n (1) and {[Zn(BIDPT)(4,4′-sdb)]·2.25H₂O}_n (2) (BIDPT = 4,4′-bis(imidazol-l-yl)diphenyl thioether, H₂oba = 4,4′-oxydibenzoic acid, 4,4′-H₂sdb = 4,4′-sulfonyldibenzoic acid), have been solvothermally synthesized and characterized. Both 1 and 2 show 2-fold interpenetrating 3D frameworks with {6⁵ ∙ 8} cds and {6⁶} dia topology, respectively. These two coordination polymers show strong luminescence and their luminescence could be quenched by a series of nitro explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitro explosives.     

A luminescent coordination polymer with potential active site for the sensing of metal cation,anion and nitrobenzene explosive

A new 1D Zn-based coordination polymer (CP), {[Zn(HBTB)(pdp)]·H₂O} (1) (H₃BTB = 1,3,5-benzenetribenzoic acid and pdp = 2-(4,6-di(pyridine-2-yl)pyridine- 2-yl)pyridine), has been synthesized under solvothermal condition and structurally characterized. The compound displays intense luminescence in solid state at room temperature with high thermal stability. Interestingly, Luminescent studies indicate that 1 could be an efficient multifunctional fluorescence material for high sensitivity metal ions, anions and organic small molecules, especially for Cu^2 +, CrO₄^2 − and nitrobenzene (NB) by luminescent quenching. The probable quenching mechanism of different analytes was also discussed.     

Decarboxylation of 5-amino-orotic acid and a Schiff base derivative by rhenium(V)

The reaction of 5-amino-orotic acid (H₂aor) with trans-[ReOBr₃(PPh₃)₂] in 2-propanol produced the complex [Re^V(apd)Br(aor)(PPh₃)₂] (1, apd^2 − = 5-imidopyrimidine-2,4-dione). The ligand apd^2 − was formed by the decarboxylation of H₂aor, and it is coordinated via the dinegative imido nitrogen only. The Schiff base derivative of H₂aor, salicylimine-orotic acid {5-(2-hydroxy-benzylideneamino)-1,2,3,6-tetrahydro-2,6-dioxopyrimidine-4-carboxylic acid; H₂sor}, was also decarboxylated in the reaction with trans-[ReOI₂(OEt)(PPh₃)₂] in ethanol to form [Re^III(cor)I(PPh₃)₂]I (2, Hcor = 5-(2-hydroxybenzylideneamino)-pyrimidine-2,4(1H,3H)-dione). Decarboxylation of H₂sor was not observed in its reaction with trans-[ReOCl₃(PPh₃)₂], which led to the isolation of [ReOCl(sor)(PPh₃)] (3), in which sor^2 − is coordinated as a tridentate ligand as expected. Spectroscopic results and the X-ray crystal structures of compounds 1–3 are also presented.     

Syntheses,structural characterization and electrochemical properties of two rare-earth–isonicotinic-acid containing silicomolybdates

Two rare-earth–isonicotinic-acid containing silicomolybdates [NH₄]₆[RE(INA)₂(HINA)(H₂O)₃]₂[α-SiMo₁₂O₄₀]₂·6H₂O [RE = Nd^III (1), Er^III (2); HINA = isonicotinic acid] have been synthesized in the conventional aqueous solution and characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. Both 1 and 2 crystallize in the triclinic P–1 space group and consist of two typical Keggin [α-SiMo₁₂O₄₀]^4 − polyanions, one isolated rare-earth-isonicotinic-acid [RE(INA)₂(HINA)(H₂O)₃]₂^2 + dimeric complex cation, six NH₄⁺ ions and six lattice water molecules. Interestingly, two rare-earth ions are linked by four INA⁻ ligands in the [Ln(INA)₂(HINA)(H₂O)₃]₂^2 + complex cation, which is very rare in polyoxometalate chemistry. The UV spectral measurements of 1 indicate that 1 is stable in aqueous solution in the pH range of 4.49–9.39. Furthermore, the electrochemical and electrocatalytic properties of 1 have been measured by cyclic voltammetry in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution at the scan rate of 100 mV·s^− 1.     

Synthesis of diiron sulfur clusters containing thiolato-1,8-naphthalene imide ligand

Three diiron sulfur clusters containing thiolato-1,8-naphthalene imide ligand, [Cp*Fe(μ-4,5-S₂-ⁿBu-NMI)(μ-CO)FeCp*] (3a), [Cp′Fe(μ-4,5-S₂-ⁿBu-NMI)(μ-CO)FeCp′] (3b), [CpFe(ⁿBu-NMI-S)]₂ (4) (3a: Cp* = η⁵-C₅Me₅; 3b: Cp′ = η⁵-C₅HMe₄; 4: Cp = η⁵-C₅H₅; ⁿBu-NMI = N-butyl-1,8-naphthalene imide) were synthesized via the reaction of N-butyl-4,5-disulfide-1,8-naphthalene imide and [Cp2Fe(μ-CO)CO]₂ (Cp2 = Cp*, Cp′, Cp). A partially desulfurated product [CpFe(ⁿBu-NMI-S)]₂ was determined in the reaction of [CpFe(μ-CO)CO]₂ with ⁿBu-NMI 4,5-dithiolate. The new complexes were structurally characterized by X-ray analysis.