Transition Metal Chemistry最新文献

A binuclear cadmium complex Cd₂(biba)₄ (Hbiba = 2-(1H-benzoimidazol-2-yl)benzoic acid) has been successfully synthesized via solvothermal method, and characterized by single-crystal x-ray diffraction, elemental analysis, infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, thermogravimetric analysis, and x-ray powder diffraction. Molecular structural analysis showed that each Cd₂(biba)₄ monomer was connected to four neighbors via intermolecular hydrogen bonds to form a 2D supramolecular structure. Fluorescence emission spectrum of Cd₂(biba)₄ was also measured in the solid state. Complex Cd₂(biba)₄ exhibited good photocatalytic activities for the degradation of methylene blue (MB) dye, sulfadiazine (SD) antibiotic and forchlorfenuron (CPPU) phytohormone under UV irradiation at room temperature. Reaction kinetics studies suggested that the photodegradation of MB, SD and CPPU were in accordance with the pseudo-first-order kinetic model. The photodegradation mechanism of MB, SD and CPPU catalyzed by Cd₂(biba)₄ was also discussed in detail. This paper presents important examples for the photodegradation of antibiotic and phytohormone using metal–organic complex as catalyst.

The development of suitable compounds for the effective treatment of cancer is highly demanded. Inorganic complexes based on cobalt and copper centers have revealed a great potential for the treatment of various cancers. The current study aimed to develop effective pyrazole-based agents against breast cancer. A pyrazole-based ligand (L: Na[EtNCSPz^Me2]) and its cobalt and copper complexes were synthesized, and the single crystals of the complexes were prepared for crystallographic analysis. The X-ray structure of the synthesized complexes indicated both of the complexes were mononuclear and monoclinic. The synthesized [Co(L)₃] complex demonstrated a six-coordinated distorted octahedral geometry around the cobalt center, while the [Cu(L)₂] complex occupied a four-coordinated seesaw geometry with N₂S₂ environment around the copper center. The compounds were evaluated for their anticancer activities against the human breast MDA-MB-231 cell lines with the MTT and flow cytometry assays to investigate the efficacy of these synthesized compounds in the induction of apoptosis and death in breast cancer cells. The investigated complexes significantly indicated more anticancer activity in compare with the free ligand and the among them Cu(II) complex showed considerable and higher activity against the tested cell lines. The molecular docking was carried out to explore the binding modes of these compounds on DNA and epidermal growth factor receptor precursor (EGFR) proteins. Altogether, in silico and in vitro investigations indicated that coordination of chelating organic ligand to the metal centers promoted the compounds anticancer activity and these complexes may be used the likely candidate for further development in cancer treatment after complementary preclinical evaluations.

A novel linear tetranuclear Ni(II) complex Ni₄L₂ {[Ni₄L₂(H₂O)₃CH₃OH]·CH₃OH·2CH₃CN·2H₂O} was constructed by employing a well-tailored compartmental ligand H₄L = (2E,N'E)-N'-(1-(3-((E)-2-hydroxy-3-methoxybenzylideneamino)-2-hydroxyphenyl)ethylidene)-2 -(hydroxyimino)propanehydrazideas with equal equivalent NiCl₂·6H₂O and NaOH via solvothermal reaction. The complex was well characterized by X-ray crystallography, elemental analysis, infrared emission spectra, UV–visible absorption spectra and thermogravimetry. The crystal structure shows that four nickel ions coordinate with two ligands to form a unique linear structure of Ni₄L₂. Besides, Ni₄L₂ act as a catalyst showed good catalytic activity for polymerization of methyl methacrylate (MMA) to obtain PMMA under mild condition.

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Multistep synthetic pathway towards a series of the anisoleboron-capped ribbed-functionalized iron(II) cage complexes was developed. Their hexachloroclathrochelate precursor was obtained by the template condensation of three dichloroglyoximate chelating ligand synthons with two molecules of 4-methoxyphenylboronic acid as a Lewis-acidic cross-linking agent on the iron(II) ion as a matrix. It easily underwent a stepwise nucleophilic substitution with S₂- and O₂-dinucleophilic aliphatic (ethanedithiolate) or aromatic (pyrocatecholate) agents, forming the stable X₂ (X = S or O)-six-membered ribbed substituent(s) at a quasiaromatic cage framework. Performing these reactions under the different reaction conditions (i.e., at various hexachloroclathrochelate-to-nucleophile molar ratios, a wide range of temperatures and a series of the solvents) allowed to control a predominant formation of its mono-, di- or triribbed-substituted macrobicyclic derivatives. Thus obtained iron(II) di- and tetrachloroclathrochelates can undergo their post-synthetic transformations with active nucleophilic agents. The latter complexes underwent a further nucleophilic substitution with the anionic derivative of n-butanthiol, thus giving the hexasulfide macrobicyclic compound with two functionalizing n-alkyl substituents in one of its three chelate α-dioximate fragments and two apical biorelevant anisole substituents. The obtained iron(II) clathrochelates, possessing a low-spin electronic d⁶ configuration, were characterized using elemental analysis, MALDI-TOF mass spectrometry, UV–Vis, ¹H and ¹³C{¹H} NMR spectroscopies, and by the single-crystal X-ray diffraction experiments for the hexachloroclathrochelate precursor, its dichlorotetrasulfide macrobicyclic derivative and the monoribbed-functionalized hexasulfide cage complex. In all their molecules, the encapsulated iron(II) ion is situated in the centre of its FeN₆-coordination polyhedron, the geometry of which is intermediate between a trigonal prism and a trigonal antiprism with the distortion angles φ from 21.4 to 23.4°. Halogen bonding between the polyhalogenoclathrochelate molecules in their crystals is observed.

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Two octamolybdate-based complexes formulated by [M₂(H₂O)₄(γ-Mo₈O₂₆)(HDIBA)₂]·H₂O [M = Co (1), Zn (2), DIBA = 3,5-di(1H-imidazol-1-yl)benzoic acid], were synthesized successfully by using hydrothermal method in the presence of 3,5-di(1H-imidazol-1-yl) benzonitrile (DICN) as initial ligand. The DIBA ligand was generated in situ from the hydrolysis of DICN ligand. The γ-octamolybdate polyoxoanion was decorated by two DIBA ligands relying on Mo−O covalent bonds between the carboxyl oxygen atom of DIBA ligand and Mo atom of polyoxoanion. The transition metal centers joined in pairs these modified γ-octamolybdate polyoxoanions into a 1D chain, which were further aggregated to result in a 2D layer. The investigations on the electrochemical performances indicated that the two complexes displayed electrocatalytic and electrochemical sensing activities for bromate and Cr(VI), which provide potential electrode materials in preparing the electrochemical sensors and electrocatalysts.

Semi-flexible aromatic polycarboxylic acids are gaining impetus in crystal engineering of functional coordination polymers. This work opens up the use of a triphenyl-tricarboxylic acid, 3,5-(4'-carboxylphenyl) benozoic acid (H₃cba), as a versatile and still unexplored linker for the synthesis of four new Mn(II), Ni(II), Zn(II), and Cd(II) coordination polymers, formulated as [Mn(μ₃-Hcba)(bpy)]_n⋅nH₂O (1), [Ni(μ-Hcba)(py)(H₂O)]_n (2), [Zn(μ-Hcba)(phen)(H₂O)]_n⋅nH₂O (3), and [Cd(μ₃-Hcba)(bpy)]_n⋅nH₂O (4). These compounds were prepared via a facile hydrothermal procedure using metal(II) chlorides, H₃cba, and supporting N-donor ligands (2,2΄-pyridine, bpy; pyridine, py; 1,10-phenanthroline, phen) acting as crystallization mediators. Compounds 1–4 were fully characterized and their X-ray crystal structures were established, disclosing the metal–organic architectures that range from 1D double chains (1, 4) to 1D chains (2, 3). Thermal and catalytic properties of 1–4 were also investigated. In particular, catalytic potential of the obtained coordination polymers in the Knoevenagel condensation of benzaldehydes with propanedinitrile was evaluated, disclosing an excellent performance of several heterogeneous catalysts with up to 100% product yield.

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Four new Mn(II), Ni(II), Zn(II), and Cd(II) 1D coordination polymers have been constructed and the structures and catalytic properties of the polymers were investigated.

New binuclear MnPt µ-vinylidene complexes Cp(CO)₂Mn(µ-C=CHPh)Pt(CN–Ad)(L) [L=PPh₃ (1a), P(OPrⁱ)₃ (2a)] bearing a terminal platinum-coordinated 1-adamantyl isocyanide ligand were prepared by the treatment of Cp(CO)₂Mn(µ-C=CHPh)Pt(CO)(L) [L=PPh₃ (1b), P(OPrⁱ)₃ (2b)] with CN-Ad. At the same time the reaction between Cp(CO)₂Mn(µ-C=CHPh)Pt(L)₂ [L=PPh₃ (1c), P(OPrⁱ)₃ (2c)] and CN-Ad did not proceed. The new complexes were characterized by IR and ¹H, ¹³C, ³¹P NMR spectroscopy. The molecular structure of Cp(CO)₂Mn(µ-C=CHPh)Pt(CN–Ad)[P(OPrⁱ)₃] (2a) was determined by an X-ray diffraction study. The redox properties of the new complexes and their reactions of chemical oxidation were studied. An influence of the platinum-coordinated 1-adamantyl isocyanide ligand on the properties of the synthesized µ-vinylidene compounds 1a and 2a was revealed.

By using 2, 2'-biimidazole (2, 2′-biim) and 2, 2′-bipyridine (2, 2′-bipy) as structure-directing agents (SDAs), two cadmium diphosphonates, [Cd₂(H₂L)₂(H₂O)] (1) and [Cd₅(HL)₂(H₂L)₂]·4H₂O (2) (H₄L = 4–F–C₆H₄CH₂N(CH₂PO₃H₂)₂), have been hydrothermally synthesized. The introduction of different N-heterocyclic aromatic SDAs results in the diverse structures, thermal stabilities, and luminescent properties. Structural analyses reveal that both 1 and 2 show three-dimensional (3D) supramolecular structures wherein the adjacent layers are further connected by moderately π–π stacking interactions or hydrogen-bond interactions. Among them, the thermal stability of 1 is higher than 2. Surprisingly, 1 displays excellent luminescent performance, whereas 2 shows no luminescent signal. Based on the intense luminescence of 1, it can serve as a high selectively and sensitively luminescent sensor for Hg²⁺ with a low detection limit of 3.1 × 10^–7 M in aqueous solution. Additionally, the probable sensing mechanism for 1 has also been investigated in detail, which can be assigned to the weak interaction between the uncoordinated O sites from the H₂L^2– ligands and Hg²⁺.

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Two cadmium diphosphonates with different structures and luminescent properties have been hydrothermally obtained by using N–heterocyclic aromatic (2, 2′–biim and 2, 2′‒bipy) compounds as SDAs. 1 displays excellent luminescent performance, whereas 2 shows no luminescent signal. Furthermore, 1 can serve as a luminescent sensor for Hg²⁺ in water

Three isostructural, Iron(III), Manganese(III) and Chromium complexes, with a tetradentate Schiff base ligand (H₂L²) from o-phenylenediamine and o-vanillin having the general formulae, [M(H₂L²)(C₂H₃O₂)(H₂O)], where M = Cr, Mn, Fe) have been prepared. The complexes were then subsequently characterized by physico-chemical and spectroscopic methods and further investigated for their magnetic nature. All the complexes are neutral mononuclear species and crystallize in a triclinic space group P-1(2). Single-crystal diffraction studies reveal that the ligand, H₂L², coordinates to the central metal ion in a tetradentate fashion through both the azomethine nitrogen and the deprotonated phenolic oxygen generating neutral complexes. One of the acetate counter anions and a water molecule is involved in the coordination, generating a distorted octahedral geometry in all the complexes. Temperature dependence magnetic susceptibility was measured in a squid magnetometer in the temperature range 300–1.8 K and reveals that all of the three complexes show antiferromagnetic behavior in the temperature range studied. The experimental susceptibility data fitting, by considering the intermolecular interactions, enabled to estimate the magnetic anisotropy D and lead to the parameters (D =  + 0.14 cm⁻¹ and zJ =  − 0.35 cm⁻¹) for Fe^III and (D =  − 3.95 cm⁻¹; E =  + 0.54 cm⁻¹; zJ =  − 0.35 cm⁻¹) for Mn^III ions. This study is aiming and boosting to 'open up' our interest to focus more on mononuclear complexes with SMM character with first-row transition metals, which will be more interesting as far as the application side is concerned.

To further develop the active site mimics of azadithiolate-bridged [FeFe]-hydrogenases, a series of new diiron azadithiolate complexes [{(μ-SCH₂)₂N(C₆H₄CH₂CH₂OC(O)R)}Fe₂(CO)₆] (R = CH₂C₆H₄Me-p, 2; C₆H₅, 3; CH₃, 4) bearing bridgehead N-derivation were successfully prepared by facile esterification reaction of parent complex [{(μ-SCH₂)₂N(C₆H₄CH₂CH₂OH)}Fe₂(CO)₆] (1) and different carboxyl compounds RCO₂H in the presence of 4-dimethylaminopyridine (DMAP) as catalyst and dicyclohexylcarbodiimide (DCC) as dehydrating reagent. Complexes 2–4 have been fully characterized by means of elemental analysis, FT-IR and NMR (¹H, ¹³C) spectroscopies, and especially for 2 by X-ray crystallography. Further electrochemical and electrocatalytic properties of target complexes 2–4 and reference analogue 1 were studied and compared in the absence and presence of acetic acid (HOAc) as a proton source by cyclic voltammetry (CV), indicating that they may be considered as the active biomimetic electrocatalysts for proton reduction to hydrogen (H₂).