Transition Metal Chemistry最新文献

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.

Transition metal with variable oxidation states has always been a point of attraction since many decades for scientists with special focus in the field of catalysis, biologically active agents, therapeutic drugs, etc. Among these, vanadium is a metal which is of multi-dimensional potential for industry, pharmaceutics, physiology, etc. Albeit the fact that inorganic vanadium salts like Na₂VO₃ and VOSO₄ have shown considerable medical potential, yet their low absorbance, higher toxicity and excretion through feces and urine drifted the attention of scientist to synthesize novel vanadium compounds/organic polyoxovanadate (POV) having versatile therapeutic potential, better absorbance and specific intra-/intercellular biomolecular interaction with various cell signaling pathways, resulting in better therapeutic activities. In past few decades, this area of research has gained much attention but still need to be done a lot in future. Keeping in mind the therapeutic scope of various vanadium complexes, the present review article is written with the purpose of providing comprehensive overview to those who are interested to dive and explore the possibility for the synthesis of new vanadium complexes as drug with its therapeutic properties. Our study aims at reporting the biphasic behavior of vanadium, a range of vanadium compound with special focus on its anti-diabetic, anti-bacterial, anti-viral, cardiovascular, anticancer, anti-oxidant, alkaline phosphatase (ALP) inhibitor properties and their probable mechanism cited in recent leading literature databases. Analogy of vanadate with phosphate responsible for its interaction with various phosphatase enzymes like ALP, protein tyrosine phosphatase (PTP), etc. in the mechanistic point of view is analyzed. The multi-directional study carried out so far on vanadium complexes and its mechanistic interaction at biomolecular level need to be systematically summarized for further innovation in drug discovery and to make new avenues in the synthetic metallodrug fields to fight against some lethal diseases.

A new Cadmiun(II) coordination polymer, {[Cd(µ-mptrz)₂].0.5((CH₃)₂SO)}_n was prepared from the reaction of CdBr₂ with 4-methyl-4H-1,2,4-triazole-3-thiol (Hmptrz) ligand in methanol. The coordination polymer was thoroughly characterized by elemental analysis, IR, UV–Vis, ¹HNMR spectroscopies, and thermogravimetric analysis. Moreover, its structure was studied by the single-crystal diffraction method. Compound 1 has a 1D chain structure. Furthermore, crystal structure is stabilized by intermolecular weak interactions, for example, C–H···O, C–H···N, and C–H···S hydrogen bonds. Besides, the photoluminescence of 1 has been investigated. This compound exhibits photoluminescence with an emission maximum of 321 nm upon excitation at 259 nm. The present work is a combined experimental and computational study. Quantum chemical parameters such as bond lengths, bond angles, HOMO–LUMO energy levels, energy band gap (Delta E), chemical hardness η, the dipole moment μ, and Natural bond orbital (NBO) analysis of the compound were investigated using the DFT at M06/GENECP (6-31 g(d) and LANL2DZ) basis sets for compound 1. Our calculation results have shown that compound 1 has an energy band gap (∆E = 3.857 eV), indicating a high recommendation for a semiconductor compound. The optimized geometry of the Cd(II) coordination polymer is shown in good agreement with single crystal X-ray data. UV/Vis spectra are calculated with the time-dependent density functional theory (TD-DFT) method. Furthermore, TD-DFT displays intraligand transition (ILCT) between triazole bridging ligands. Moreover, NBO analysis of the Cd(II) coordination polymer indicates that the lone pair donor orbital interaction between the N, S, and O lone pairs and π*, σ* anti-bonding orbitals provides stronger stability. Additionally, Solid-state density functional theory (DFT) calculations were performed on 1 using the program VASP to understand the electronic states and conduction pathways of the coordination polymer.

A new copper(II) complex, [Cu(L)NO₃]NO₃·2H₂O, has been synthesized with N, N'-bis-(benzimidazol-2-yl-methyl)-hexane-1,6-dicarboxamide as a ligand, L = GBSA (Ahuja and Mathur in Spectrochim Acta Part A 83:180–186, 2011). The single-crystal X-ray structure characterization confirms that copper(II) ion in the complex possesses a distorted penta-coordinate geometry with one of the nitrate anions bound to copper(II) as a monodentate ligand. The N₂O₂ equatorial plane of the copper(II) complex comprises of carbonyl oxygen atom (O1), nitrate oxygen atom (O3) and two benzimidazole nitrogen atom (N1,N4), while the axial position is occupied by oxygen atom (O2) of amide carbonyl. Low-temperature EPR study indicates distorted tetragonal geometry, while cathodic E_1/2 value indicates stabilization of copper in + 2 oxidation state in solution. TGA data demonstrated thermal decomposition pattern of the complex. The complex was studied as a catalyst for the oxidation of aromatic and aliphatic primary and secondary amines in ionic liquid, [BMIM][BF₄] as a solvent and TBHP as an external source of oxygen at 45–50 °C, affording good yields under mild conditions. Products formed were analyzed by GCMS.

The six-coordinate ruthenium(II) porphyrin complexes (OEP)Ru(CO)(Q), (OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion; Q = quinoline, Qnl (2); quinine, QN (3)) have been prepared from (OEP)Ru(CO) (1) and characterized by MS, IR, UV–visible and ¹H NMR spectroscopy. The X-ray crystal structure of 2 has been determined, which reveals quinoline coordination to Ru through the nitrogen atom. In the crystal packing of 2, the two Qnl groups of adjacent porphyrins are positioned relatively parallel to each other at a close distance of 3.30 Å, implying a relatively strong π-π interaction. The X-ray crystal structure of 1 was obtained, which revealed coordination of the water to the ruthenium center. By comparing the spectroscopic data for 1, 2 and 3, it was determined that the site of binding of QN to Ru is likely through the nitrogen atom of the quinoline moiety. The redox behavior of the complexes at a Pt working electrode studied in a CH₂Cl₂ solution with NBu₄PF₆ as support electrolyte by cyclic voltammetry revealed oxidations that are porphyrin-centered.

Graphical abstract

Background

The study and development of fluorouracil metal complexes are important in the development of new synthetic methods and materials with applications in pharmaceuticals, agrochemicals, and materials science.

Mothodology

A new Cd(II) compound, (H-5FC) [(H-5FC) Cd Cl ] (1), (where H-5FC is HFlucytosine), was successfully synthesized and crystallized by slow evaporation at room temperature. The compound was characterized by single-crystal X-ray diffraction technique and UV–Visible spectroscopy.

Results

The structure shows that the compound constitutes of an independent protonated (H-5FC)⁺ cation and two protonated flucytosine molecules that coordinate to the Cd(II) ion via an oxygen atom to form a trinuclear [(H-5FC)₂Cd₃Cl₁₀]²⁻ anionic moieties. The independent protonated (H-5FC)⁺ bridges the [(H-5FC)₂Cd₃Cl₁₀]²⁻ anions via N/C–H···Cl/O hydrogen bonds. Supramolecular structure analysis of (1) with the aid of Hirshfeld calculations showed the importance of the H···Cl, O···H, C···Cl, and F···Cl interactions. Their percentages were calculated to be 42.2, 10.3, 6.6, and 8.7%, respectively. The band gap energy of the compound, deduced from the Tauc plot of the absorption spectrum, indicated a wide energy gap of 3.65 eV.

A novel copper complex [Cu(μ₂–OH)(1,10-phenanthroline)(4-aminobenzenesulfonic acid)·3H₂O]₂ (1) was synthesized and characterized by X-ray single-crystal diffraction, elemental analysis and IR spectroscopy. X-ray crystallography of complex 1 showed strictly planar bridged μ₂–Cu₂(OH)₂ core where copper (II) center exhibited a distorted square pyramidal coordination geometry. The interaction of the complex with calf thymus DNA (CT DNA) was investigated by absorption titration and viscosity measurement. The results revealed an intercalation binding between DNA and complex 1 with a binding strength of 6.0731 × 10⁶ ± 0.0032 M⁻¹. The antitumor capacity of the complex was tested in vitro against human colorectal (HCT 116) cancer cell lines by metabolic tests, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide reagent. Complex 1 showed remarkably low IC₅₀ values of 4.844 ± 0.025 μM compared to 5-fluorouracil (7.3 μM), a widely used clinical antitumor drug.

In this study, ZnO thin films were prepared with different precursors using the spray pyrolysis technique, zinc acetate (ZAC-0.2), zinc chloride (ZCL-0.2), and dehydrated zinc nitrate (ZNH-0.2) precursors. The formation of ZnO thin films was confirmed using a variety of characterization techniques, including UV–vis spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). The primary aim of this study is to explore how different precursor materials affect the properties of ZnO thin films and to demonstrate the efficacy of these films in removing copper ions from wastewater. The structure, microstructure, and optical properties of these materials were investigated, along with their adsorption activity. The results revealed that all ZnO films exhibited a hexagonal wurtzite crystal structure. The ZAC-0.2 sample demonstrated the highest transparency within the 400–800 nm wavelength range. The sample with the least band gap was ZNH-0.2, with a value of 1.96 eV, and exhibited the highest Urbach energy (Eurb) at 1.150 eV. Moreover, the ZnO thin films displayed high efficiency in removing 80% of copper ions from an aqueous solution.

Chromium–chromium and chromium–ligand bonding interactions existing in the [Cp*₂Cr₂(CO)₂(μ-PMe₂)₂], [Cp*₂Cr₂(CO)₄(μ-H) (μ-PMe₂)], and [Cp*₃Cr₃(CO)₃(μ-S) (μ-PMe₂)] complexes are studied at DFT level of theory. Several local and integral topological parameters of the electron density such as electron density ρ_(b), Laplacian ∇²ρ_(b), local energy density H_(b), local kinetic energy density G_(b), potential energy density V_(b), ε_(b), and bond localization index (A, B) were evaluated according to QTAIM (quantum theory of atoms in a molecule). The calculated topological parameters are consistent with the relevant transition metal complexes in the literature. The computed data allow comparisons between the topological properties of related but different atom–atom interactions, such as other ligand-bridged Cr–Cr interactions and H-bridged ligand interactions versus S and P ligands. The QTAIM results confirm that the metal atoms bridged by two phosphorus atoms in binuclear complex1 are connected through a localized Cr–Cr bond that implicates little electron density (0.040). In contrast, such bonding was not found in binuclear complexes 2 (bridged by H and P) and trinuclear complex 3 (bridged by S and P). A multicenter 4c–5e, 4c–3e, and 4c–4e interactions are proposed to exist in the bridged parts, Cr(1)–P(1)–Cr(2)–P(2) in complex 1, Cr(1)–H–Cr(2)–P in complex 2, and Cr3–S in complex 3, respectively. Finally, the delocalization indices δ(Cr····O) calculated for the Cr–CO bonds in the three compounds confirm the presence of significant CO to Cr π-back-donation except for Cr(2)–O(2) and Cr(3)–O(1) bonds in complex 3, indicating that there is no π-back-donation.

Two dinuclear and centrosymmetric silver-containing complexes, namely [Ag₂(3,5-dmpz)₂(3,5-dmpz methanol)₂(tbtc)] (1) and [Ag₂(3,5-dmpz)₂(3,5-dmpz methanol)₂(dbtc)] (2) (3,5-dmpz: dimethylpyrazole; 3,5-dmpz methanol: 3,5-dimethylpyrazole methanol; H₂tbtc: tetrabromoterephthalic acid; H₂dbtc: 2,5-dibromoterephthalic acid), were prepared and characterized. X-ray crystallographic data of 1 and 2 revealed that trigonal environment of the Ag ions has a “compressed Y’s” geometry. The antimicrobial activity of 1 and 2 was tested against the Gram-positive, Gram-negative bacteria and fungus, displaying the better inhibiting activity than the individual AgNO₃ and 3,5-dimethylpyrazole, especially for Candida albicans (IC₅₀ 2.5 ± 0.1 mg mL ⁻¹ and 2.8 ± 0.2 mg mL⁻¹). The quantified IC₅₀ values displayed that complexes 1 and 2 were more effective against fungus than the Gram-negative bacteria and Gram-positive bacteria.