Polyhedron最新文献

Solid solutions of 4-methylpyridinium bromoiodobismuthates have been isolated from aqueous solutions and structurally characterized. It was found that the composition of the resulting solid solutions [PiH]₄Bi₂X₁₀, [PiH]BiX₄, and [PiH]₃Bi₂X₉ (PiH = 4-methylpyridinium; X = Br, I) depends on the ratio of organic cation/bismuth and bromine/iodine in the initial solution. The existence of two polymorphic modifications of [PiH]BiX₄ in the system formed at different ratios of halide ions has been demonstrated. Possible reasons for the unequal occupation of halogen positions in the crystal lattice by different halogen atoms are analyzed.

The stability of polynuclear superhalogen anions composed of BiF₅ building blocks was investigated using ab initio electronic structure methods and flexible basis sets. A comprehensive exploration of the ground state potential energy surfaces of (Bi₂F₁₁)⁻, (Bi₃F₁₆)⁻ and (Bi₄F₂₁)⁻ anions, which can be viewed as comprising BiF₅ fragments and an additional fluorine atom, led to the identification of their isomeric structures. It was found that the most stable isomers, predicted to dominate at room temperature, correspond to chain-like extended structures containing BiF₆ subunits, with fluorine ligands arranged octahedrally around Bi atoms, sharing F atoms to form Bi–F–Bi bridging linkages. The vertical electron detachment energies of the (Bi_nF_5n+1)⁻ anions (n = 1–4) were found to be very high (ranging from 10.91 to 13.36 eV) and increased with the number of bismuth atoms (n) and thus the BiF₅ building blocks involved in the structure. Thermodynamic stability of the (Bi_nF_5n+1)⁻ anions (i.e., their susceptibility to fragmentation) was also verified and discussed.

We report the synthesis of a dinuclear cadmium (II)-based coordination polymer, {[Cd₃(BTC)₂(H₂O)₃]·1.5Beib·9H₂O}_n (1), via a solvothermal method using CdCl₂, 1,3,5-benzenetricarboxylic acid (H₃BTC), and 1,4-bis(2-ethylimidazol-1-yl)butane (Beib) in a mixed solvent of N,N-Dimethylacetamide (DMA) and distilled water. The photocatalytic efficiency of 1 was evaluated for the degradation of organic pollutants such as 2,4-dinitrophenol (DNP), 2,4,6-trinitrophenol (TNP), 3-nitrophenol (MNP), and 4-nitrotoluene (PNT) in wastewater. The complex showed remarkable photocatalytic activity, with 20 ppm DNP achieving 97.17 % degradation using 30 mg of photocatalyst 1 within 100 min. Trapping experiments confirmed superoxide radicals and h⁺ as the primary active species. The complex also demonstrated excellent stability and reusability across multiple cycles in various water sources.

Dichromate (Cr₂O₇²⁻) and permanganate (MnO₄⁻) ions have been important targets for sensing and detection in the field of luminescent complexes and their corresponding ligands due to their significant impact on the ecological environment and human health. However, many Cu(I) complexes with good room-temperature phosphorescence are rarely used as luminescent sensors for ions in water due to the insolubility and the disproportionation of the Cu(I) ion. Herein, 2,6-di-1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl-4-tertbutylphenol (diptpH₃) and its two luminescent binuclear Cu(I) complexes, [Cu(diptpH₃)(POP)]ClO₄ (1) and [Cu(diptpH₃)(xantphos)]ClO₄ (2), were designed and synthesized (POP = bis[(2-diphenylphosphino)phenyl] ether, and xantphos = 9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-xanthene). All compounds in DMSO/H₂O (1: 9, v: v) show high stability to water, which was confirmed by the results of electrospray ionization mass spectrometry (ESI-MS). Cr₂O₇²⁻ and MnO₄⁻ ions showed high luminescence quenching coefficients (Cr₂O₇²⁻: 3.042 × 10⁴ − 2.946 × 10⁵ M⁻¹; MnO₄⁻: 1.476 × 10⁴ − 2.254 × 10⁵ M⁻¹) for all the three compounds. DiptpH₃, complexes 1 and 2 exhibited good luminescent sensing properties toward Cr₂O₇²⁻ and MnO₄⁻ ions with short response times, good selectivity and low detection limits (Cr₂O₇²⁻: 1.845 × 10⁻⁷ − 2.359 × 10⁻⁶ mol⋅L⁻¹; MnO₄⁻: 1.850 × 10⁻⁷ − 6.221 × 10⁻⁶ mol⋅L⁻¹) in DMSO/H₂O. The plausible sensing mechanisms were fully discussed.

The new organotantalum(V) chloride (η⁵-permethylindenyl)tetrachlorotantalum, Ind*TaCl₄, was prepared by addition of previously-unreported Ind*SnBu₃ to TaCl₅ in toluene at 70° in 53 % isolated yield. The solid-state four-legged piano-stool structure, consistent with solution multinuclear NMR spectroscopies, demonstrated that tantalum is bonded to all carbons of the five-membered ring of the permethylindenyl ligand, with little deviation in the Ta-C distances. The permethylindenyl ring torsional angles for the three independent molecules in the unit cell vary from 2.46(17)° to 5.10(17)°. The cyclic voltammogram of Ind*TaCl₄ in tetrahydrofuran showed one reversible reduction feature at −1.24 V [Ta(V)/Ta(IV)] and one quasi-reversible reduction feature at −1.65 V [Ta(IV)/Ta(III)] vs. Fc/Fc⁺. The UV/vis LMCT absorption λ_max at 593 nm (ε = 2000 M⁻¹ cm⁻¹) in toluene is remarkably red-shifted from that of the known η⁵-pentamethylcyclopentadienyl analog, luminescent-yellow Cp*TaCl₄. TD-DFT calculations were used to explain the comparative UV/vis absorption spectra.

This study aimed to present an optimized synthetic pathway for a complex formed between copper (II) metal ion and tannic acid (TA), which have a variety of pharmacological properties. The study also focused on characterizing this metallodrug, carrying out in vitro antioxidant and acetylcholinesterase enzyme (AChE) inhibition assays, and performing in vivo toxicity assay against zebrafish (Danio rerio), thus expanding the area of study involving syntheses of metal complexes to act as therapeutic agents. Through various characterization techniques, including UV–Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Thermal Analysis (TG and DTG), ¹H Nuclear Magnetic Resonance (¹H NMR), Inductively Coupled Plasma with Optical Emission Spectrometry (ICP-OES), and Electron Paramagnetic Resonance (EPR), it was confirmed that the metal ion is coordinated to the ligand, exhibiting distorted planar square geometry with mononuclear copper (3.10 ± 0.10 % copper by ICP-OES). In vitro tests demonstrated that the TA–Cu complex presents antioxidant activity against DPPH (IC₅₀ = 2.26 ± 0.01 µg mL⁻¹) and ABTS (IC₅₀ = 1.91 ± 0.07 µg mL⁻¹) radical scavenging assays. These results were more promising than those obtained for the TA (4.25 ± 0.03 µg mL⁻¹ and 3.37 ± 0.03 µg mL⁻¹, respectively). In the in vitro inhibition of AChE assay, the TA–Cu complex (4.07 ± 0.04 µg mL⁻¹) presented a lower IC₅₀ value than TA (5.80 ± 0.09 µg mL⁻¹), indicating that coordination to the metal center Cu (II) was able to improve the anticholinesterase activity of the free ligand. Furthermore, the TA–Cu complex did not show toxicity in the in vivo test with adult zebrafish for 96 h at the tested doses of 4–40 mg kg⁻¹, with LD₅₀ >40 mg kg⁻¹. Thus, it is estimated that the TA–Cu complex is a metallodrug with anticholinesterase potential, representing a promising strategy for conducting future pre-clinical studies in models of Alzheimer’s disease.

Thiazoles and their derivatives are one of the most active classes of compounds known for their wide spectrum of bioactivity. Metal complexes, based on them, show antitumor potential that is attractive for investigations. Herein, we report 6 new biologically active thiazole-based complexes have been synthesized. The iridium- and palladium-based coordination compounds obtained by the precipitation method were characterized using elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), magnetic measurements, thermogravimetric analysis coupled with mass spectrometry (TGA-MS), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Spectroscopic data helped to propose the formulas of the complexes and indicated that all ligands acted in a monodentate manner. Water molecules were identified by thermal analysis and FTIR spectroscopy. Mathematical analysis and evaluation of thermodynamic parameters including entropy (ΔS), Gibbs free energy (ΔG), and activation energy (E) were performed using the Coats–Redfern method for all complexes. The biological potential (anticancer, antibacterial, and antifungal properties) of compounds was analyzed by biological evaluation studies. Investigated CT-DNA studies revealed that the prepared compounds were intercalatively bound to the DNA. Cytotoxicity analyses showed that complexation with Ir(III) increased the toxicity of L2 towards both tested cell lines (LN-229 and MDA-MB-231), while complexation of L3 with Pd(II) significantly increased cytotoxic activity against LN-229. Due to this, the further biological studies, such as apoptosis/necrosis detection, cell cycle analysis and JC-1 fluorescence measurements were performed on this pair of compounds.

Copper (II) acetate reacted with 2-oxindole semicarbazone (2-Hoxsc, H¹L), 3-methyl 2-oxindole semicarbazone (3-MeHoxsc, H²L) and 6-Chloro-2-oxindole semicarbazone (6-ClHoxsc, H³L) in 1:2 (M:L) molar ratio to form complexes of general formula, [Cu(L₂)] (¹L, 1; ²L 2; ³L 3. Stoichiometric ratio of complexes was established using UV–Vis spectroscopy. All the complexes were characterised by the CHN analysis, IR, ESR spectroscopy and Mass spectrometry. From the ESR spectrum, g values obtained (g_‖ = 2.20; g_⊥ = 2.05) for complex 2 confirms axial symmetry for this complex, whereas a broad isotropic signal in 1 and 3 (g_iso = 2.060, 1; 2.057, 3) indicates extensive exchange coupling. All the synthesized compounds (ligands and complexes) complexes were examined for their anti-tubercular activity against M. tuberculosis H37RV strain. Compounds were also tested for their anti-bacterial (B. subtilis, K. pneumonia) and antifungal (C. auris, C. albicans) activities. Biological investigations revealed that the antimicrobial activities (anti-TB, antibacterial and antifungal) of ligands get improved on complexation with Cu (II) due to formation of chelate ring, which can make the ligand a more powerful biological agent. Complex 3 has shown excellent anti-TB (MIC = 1.6 g/ml) and antibacterial (ZOI = 26 mm at 5 mg/mL) activities. Strong binding of complex 3 was observed (K_b = 24.22 × 10⁵ M⁻¹) with Human Serum Albumin (HSA) using fluorescence spectroscopy. Molecular modelling of complex 3 was also done with the active site of amino acid of M. tuberculosis enoyl reductase. The minimal binding energy of −10.1 kcal/mol indicated significant intermolecular interaction between M. tuberculosis enoyl reductase and complex 3 and is in well agreement with experimental data.

A new acetato bridged 2D coordination polymer with general formula of [Mn(µ-4-ambh)(µ-OAc)(OAc)]_n (1) was prepared by the reaction of Mn(OAc)₂·4H₂O with 4-aminobenzohydrazide (4-ambh) in equimolar ratio. The reaction was done in methanol under reflux condition and the single crystals of 1 were obtained by evaporation of the solvent. The structure of this compound was determined by X-ray analysis, and its spectroscopic properties and thermal stability were also studied. These studies indicated that in this compound, the manganese ions are connected by a mixture of acetate and 4-ambh bridges to form a 2D polymeric network at the bc crystallographic plane. The intermolecular and intramolecular interactions were investigated by Hirshfeld surface analysis. Magnetic studies revealed a dominant antiferromagnetic intermetallic coupling of J = −0.78 cm⁻¹ magnitude. Magnetization measurements suggest a diamagnetic ground state and a small gap of 1.59 cm⁻¹ with the first excited state; while the axial zero-field splitting parameter, D, was calculated at −0.21 cm⁻¹.

Silver(I) complexation with boron cluster anions [B_nH_n]²⁻ (n = 10, 12) and chelating 1-substituted-2-aldiminebenzimidazoles 1-(1-methylbenzimidazol-2-yl)-N-phenylmetanimine (L¹) and 1-(1-benzylbenzimidazol-2-yl)-N-cyclohexylmethanimine (L²) in systems AgNO₃/[B_nH_n]²⁻/L and {Ag₂[B_nH_n]}_m/L, as well as with azaheterocyclic ligands 2,2ʹ-bipyridine (bipy) or 1,10-phenanthroline (phen) in the system AgNO₃/[B_nH_n]²⁻/L has been first studied. The effect of the organic ligand on the composition and structures of the resulting compounds has been shown. As a result, binuclear complexes [Ag₂L₂[μ–B_nH_n]] with bridging boron cluster anions with various combinations of coordination modes (edge-edge and edge-face for the [B₁₀H₁₀]²⁻ anion, edge–atom and nontrivial asymmetric for the [B₁₂H₁₂]²⁻ anion) have been synthesized and structurally characterized for benzimidazole derivatives L¹ and L². When using bipy or phen as ligands, polymeric complexes {Ag₂L[B₁₀H₁₀]}_m or {Ag₂L₂[μ-B₁₂H₁₂]}_m have been obtained.