Transition Metal Chemistry最新文献

A new aza-thia macrocycle compound was obtained with high dilution reaction. A new zinc(II) phthalocyanine containing four 17-membered macrocycle moieties with nitrogen-sulfur donor atoms was synthesized in a multi-step reaction sequence. Zn(II) phthalocyanine (S₄N-ZnPc) and all of the new compounds were characterized by elemental analysis and different spectroscopic methods such as ¹H NMR, ¹³C NMR, IR, UV–vis and mass. Obtained macrocyclic compounds 6 and S₄N-ZnPc were used in solvent extraction of metals such as Ag⁺, Hg²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Cr³⁺ from aqueous phase to the organic phase. The results of two-phase extraction studies on new macrocyclic compounds showed very high selectivity for silver ions compared to other metal cations.

Two new tetradentate symmetrical Schiff bases derived from 2,2’-diamino-4,4’-dimethyl-1,1’-biphenyl or its dibromo substituted analog and 3,5-diiodosalicylaldehyde were synthesized. The reactions of these Schiff bases with zinc acetate generated the corresponding Zn(II)-complexes in which the zinc atom is bonded through the two azoimine nitrogen atoms in addition to the two oxygen atoms of the deprotonated hydroxyl groups. The Schiff bases and their Zn(II) complexes were characterized using UV-Vis, ¹H- and ¹³C-NMR, IR spectroscopy and elemental analysis. The structures of the two Schiff bases as well as the two zinc(II) complexes were further approved by single crystal X-ray analysis.

Pyridine (py) and ammonia (NH₃) have been widely used as raw materials in manufacturing processes; however, both are volatile, and their vapor is detrimental to human health. To limit the exposure of those who work with py and NH₃ vapor, the development of effective techniques to sense atmospheric levels of py and NH₃ in order to decrease their concentration when required is important. In the present study, we found that crystals of bis(benzimidazole)NiCl₂ (1, bis(benzimidazole) = phenylbis(benzimidazol-2-yl)methane)) adsorb py and NH₃ vapor with a concomitant color change from purple to green (py) or light purple (NH₃). Powder X-ray diffraction, UV–Vis diffuse reflectance, and IR spectroscopic studies revealed that these color changes are induced by the formation of trans-[NiCl₂(py)₄] (2) or [Ni(NH₃)₆]Cl₂ (3). A time-dependent analysis of the py-vapor adsorption indicated that the formation of 2 from 1 proceeds non-uniformly in the solid. Crystals of 1 were furthermore found to adsorb py or NH₃ even at low concentrations (py: ~ 6 ppm; NH₃: ~ 33 ppm), albeit that a color change was not observed in these cases.

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In this paper, the mechanisms of reactions involving complexes with tetraazamacrocyclic (mac) ligands against nitrosyl ligands in an aqueous medium were explored, with emphasis on reactivity to nitric oxide (NO) and analog species, like nitrite ion (NO₂⁻). The reactions between [RuCl(OH₂)(mac)]²⁺ with NO and [RuCl(OH)(mac)]²⁺ with NO₂⁻ were performed in an aqueous solution within pH 1 or 7, and the rate constants (k) and the thermodynamic parameters (∆H^#, ∆S^#) of activation were determined. The reaction between NO and the complex with cyclen is faster than that with the complex with cyclam. However, the reaction of the cyclen complex with NO₂⁻ is slower than NO. This research provides detailed reaction kinetics and thermodynamic activation parameters for these interactions for the first time. In addition, the redox processes of coordinated NO⁻ and NO₂⁻ ligands to ruthenium were evaluated and the electrochemical release of NO from nitrosyl compounds upon electrochemical potential application. Our findings bring significant contributions in elucidating mechanisms related to NO capture both in vitro and in vivo.

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A novel CuO–SiO₂ nanoadsorbent, incorporating copper oxide (CuO) and silicon dioxide (SiO₂), has been successfully synthesized using three distinct preparation processes: Mode-A (solution and solution), Mode-B (solution and nanoparticles), and Mode-C (nanoparticles and nanoparticles). The investigation focuses on evaluating the efficiency of the CuO–SiO₂ nanoadsorbent, considering its synthesis process, reusability, and sustained performance over time, particularly in the removal of Rose Bengal dye. Characterization results revealed the formation of CuO–SiO₂ nanocomposites structure irregular shapes morphology across all three-preparation processes. The average particle sizes for Mode-A, Mode-B, and Mode-C nanocomposites were determined as 18.1 nm, 15.6 nm, and 14.8 nm, respectively. Furthermore, the band gap energies of the CuO–SiO₂ nanocomposites were measured at 2.2 eV, 1.8 eV, and 3.29 eV for Mode-A, Mode-B, and Mode-C, respectively. Remarkably, the CuO–SiO₂ nanocomposite prepared using Mode-B demonstrated superior photocatalytic activity in degrading the anionic dye Rose Bengal, achieving a degradation coefficient of 84.8%. In comparison, CuO NPs, tested under the same experimental conditions (120 min contact time, pH = 7, temperature of 25 °C, and solar light irradiation), achieved a degradation coefficient of 78.8%. These findings highlight the potential of the CuO–SiO₂ nanoadsorbent, particularly when synthesized via Mode-B, for effective and environmentally friendly dye degradation applications.

Nickel(II) complexes of 1H-tetrazol-5-acetic acid (H₂L) and oligopyridines (1,10-phenanthroline /2,2’-bipyridine derivatives) have been synthesized and characterized by physicochemical methods (elemental and thermogravimetric analysis, powder X-ray diffraction, and IR spectroscopy). The behavior of the complexes in solution was studied by UV–Vis spectroscopy, conductometry, and mass spectrometry. The stability of the complexes over 48 h in aqueous solution and in phosphate-buffered saline was demonstrated using UV–Vis spectroscopy. These compounds were investigated for their cytotoxic and cytostatic activity against HepG2 (hepatocellular carcinoma), and Hep2 (larynx carcinoma) human cancer cell lines. Cytotoxicity was also studied on human non-cancerous cell line MRC-5 (lung fibroblast). All the compounds did not show cytotoxic activity against the tested cell lines in 1–50-µM concentration range. However, compounds showed a cytostatic effect against HepG2 and Hep2 cell lines. The most pronounced cytostatic properties were found for the complex [Ni(dmphen)₂L]·2C₂H₅OH·2H₂O (1). In addition, we report three new crystal structures: [Ni(phen)₂L]·H₂O, [Ni(dmbipy)₂L]·2C₂H₅OH, and [Ni(dmphen)₂L]·2C₂H₅OH·2H₂O, where L^2– behaves as a bidentate ligand which is coordinated to the Ni(II) ion via N,O atoms.

Two mononuclear complexes of transition metal {Fe(II) and Cu(II)} constructed from 2-(3-(1H-imidazol-1-yl)propyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (L)and KSCN as auxiliary ligand are reported. Both the complexes were formed in refluxed condition. The complexes were characterized with different spectroscopic tools such as FT-IR, UV–vis, CHN-elemental analysis, photoluminescence. The solid-state structures were determined by single crystal X-ray diffraction method which exhibit that Fe (II) center, in complex 1, is four coordinated distorted tetrahedral geometry whereas Cu(II) center, in complex 2 is five coordinated square pyramidal geometry with slight distortion. The bulk stability was confirmed by powder XRD data. The thermal stability of both complexes was determined by thermogravimetric analysis (TGA). Various types of supramolecular interactions such as O–H…O, C–H…O, π…π, C–H…π and C–H…S were observed in the x-ray structures, and all these interactions guide the formation of 3D supramolecular architecture in the solid-state of both complexes. Besides these, the 2D-fingerprint (2D-FP) and Hirshfeld surface analysis (HSA) computations were served to prove the 2D-network packed crystal lattice interactions.

N-(2-(1H-pyrazol-1-yl)phenyl)-picolinamide ligands 3a–c and 5a–f have been easily prepared from commercially available 2-pyridinecarboxylic acid. Reaction of 3a–c and 5a–f with PdCl₂ in toluene in the presence of triethylamine gave the nine NNN pincer Pd(II) complexes 6a–i in 15–91% yields. All the new compounds were characterized by ¹H, ¹³C NMR spectra and HRMS. In addition, the molecular structures of complexes 6a and 6i have also been determined by single-crystal X-ray diffraction. The obtained palladium(II) catalysts showed efficient catalytic activity toward the Heck coupling of aryl bromides with styrenes. Under the condition of 5% catalyst loading, the expected various styrenes were obtained in moderate to high yields (up to 99% yield).

Two new manganese(III) Schiff base complexes MnL₂N₃ (1) and MnL₂NCS (2) where HL is 4-bromo-2-[(Z)-{[2-(thiophene-2-yl)ethyl]imino}methyl]phenol) were synthesized and characterized by UV–Vis. absorption spectra, FT-IR, TGA Analyses, and single-crystal X-ray diffraction technique. Structural studies reveal that the metal sites in complexes 1–2 are six-coordinated by two phenoxy oxygen atoms, two imine nitrogen atoms of two moles of Schiff base ligand, HL, and two nitrogen atoms from the azide or one nitrogen atom and one sulphur atom from thiocyanate ligands, respectively. The geometry around the metal center is twisted octahedral geometry with a MnN₄O₂ (for 1) and MnN₃O₂S (for 2) chromophore. Hirshfeld surfaces associated with 2D fingerprint plots have been used to analyze intermolecular interactions in crystal packing. Crystal packing of both complexes shows the interchain π⋯π stacking interactions between one-dimensional polymeric chains.

Mononuclear complexes of Copper(II) with (E)-N′(3,5-di-tert-butyl-2-hydroxybenzili- dene)-2-hydroxybenzohydrazide (H₃sahz)₂, Cu(Hsahz)(H₂O) and Cu(Hsahz)(DMF) were synthesized. The structure of the complexes was studied by elemental analysis, IR and EPR spectroscopy, and single-crystal X-ray analysis. It was shown that the complexes have a square-planar structure, in which the ligand is tridentate and dianionic. The coordination of Cu(II) ion is formed by the oxygen atom of the phenol group of 3,5-di-tert-butyl salicylic aldehyde, amidic oxygen atom is in enolic form, the oxygen atom of the DMF molecule and the nitrogen atom of the azomethine group. When recrystallizing from DMF/acetonitrile/ethanol = 1:2:4 solution, the water molecule in the complex is easily exchanged with the DMF molecule. The results of these studies showed that the complexes have a stronger antibacterial and antifungal effect than the ligand.