Transition Metal Chemistry最新文献

The development of molecular photocatalytic systems for CO₂ reduction is a continuous challenge for chemists. Herein, the photocatalytic reductions of CO₂ by [Co^II(L1)(η¹-ONO₂)₂] (1) (L1 = 6,6'-(pyridine-2,6-diyl)bis(1,3,5-triazine-2,4-diamine)) and [Co^II(L2)(H₂O)₂]²⁺ (2) (L2 = 6,6'-([2,2'-bipyridine]-6,6'-diyl)bis(1,3,5-triazine-2,4-diamine)) have been investigated. With Ir(ppy)₃ as the photosensitizer and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole as the sacrificial reductant in DMF/triethylamine solution under irradiation by white light-emitting diode (λ > 420 nm), CO was selectively produced with a turnover number (TON) of 36 and 89 for 1 and 2, respectively. Based on the electrochemical studies, the triply reduced [Co⁰(L2•)]ˉ species from 2 is found to be responsible for the activation of CO₂ with a large rate constant of k = 506 M⁻¹ s⁻¹. However, the strong CO binding constant of Co^I(L2)-CO adduct (K = 5.01 × 10⁶) and the slow CO release from Co⁰(L2)-CO adduct limit the catalytic efficiency.

This is an investigation on the properties of PrMnO₃ using density functional theory under varying pressure conditions ranging from 0 to 50 GPa. The study includes an analysis of the material's structural, electronic, mechanical, and thermal properties, utilizing the computational power of density functional theory. The Goldschmidt tolerance factor, enthalpy, and elastic stability criteria are used to evaluate the material's stability. The results suggest that the material is stable under these criteria. Furthermore, the optimization of the material is discussed based on the computed properties. The results show that the material exhibits good ferromagnetic and spintronic properties, making it a promising candidate for use in optoelectronic and spintronic devices. Overall, the findings highlight the potential of PrMnO₃ to be a valuable material for these applications, as revealed through the use of density functional theory.

Understanding the asymmetric catalytic mechanism involving organometallic species provides exceptional insight into the strategies for the degradation of emerging organic contaminants. The present work demonstrates such insights on the oxidation of commonly used non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac, paracetamol, ibuprofen, and aspirin using optically active novel Schiff base Co(II) complexes derived from salicylaldehyde containing five different amino acids (L-methionine, L-leucine, L-asparagine, L-tryptophan, and L-glutamic acid). Among the studied chiral catalysts, asymmetric degradation in the presence of a Co(II) complex containing glutamic acid mixed ligand showed an elevated rate of oxidation of non-amine NSAIDs such as ibuprofen (3.86 × 10^–2 s⁻¹) and aspirin (3.70 × 10^–3 s⁻¹) using H₂O₂ oxidant under visible light conditions at neutral pH. The formation of chiral intermediate species in both drugs has been detected and characterized by FTIR and Raman analysis. On the other hand, NSAIDs containing secondary amine groups (–NH–), such as diclofenac and paracetamol, generate effective coordination between the complex catalyst and the nitrogen atom. This explains the high activity of the Co(II) complex with glutamic acid mixed salicylaldehyde with 100% selectivity in the degradation of ibuprofen and aspirin. The thermodynamical feasibility of the proposed degradation route for ibuprofen and aspirin was analyzed with theoretically calculated total energy values of all the intermediates formed in each step of the proposed mechanism.

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Hollow metallic particles have a lower density than their bulk counterparts with an equivalent apparent volume; therefore, they are expected to be applied in fields requiring low density and large surface area materials. This study proposes a method for synthesizing hollow metallic Cu particles in an aqueous solution. An aqueous suspension of hollow metallic Cu particles was prepared by placing metallic Zn particles in an aqueous Cu acetate solution. Based on the displacement plating related to the standard electrode potential difference between Cu and Zn, Cu²⁺ ions were reduced to metallic Cu by receiving electrons from metallic Zn, while metallic Zn dissolved into the aqueous solution. Consequently, metallic Cu with a shell-like shape formed near the surface of the original metallic Zn particles before Zn dissolution, yielding hollow metallic Cu particles. Thus, this study revealed that the Cu acetate concentration should be appropriately controlled to fabricate hollow particles. Moreover, the developed method can easily fabricate hollow metallic particles in one step without adding external reducing agents.

Herein, a new derivative of 1,2-naphthoquinone with semicarbazide and its Schiff base complexes and ternary complexes have been synthesized with some transition metals such as Ni(II), Co(II) and Zn(II) by using the conventional reflux method and 8-hydroxyquinoline (8-HQ) as a secondary ligand for ternary complexes. All the compounds were characterized using elemental analysis, molar conductance, melting point, Powder XRD, magnetic moment measurement and various spectral techniques such as FTIR, ¹³C NMR, ¹H NMR, and Mass Spectra. The specific peak of the enolic proton in ¹H NMR spectra of the tridentate ligand (L) explained the amido-iminol tautomerism in semicarbazone. In addition, powder XRD analysis and TGA confirmed the crystalline nature and the thermal study of metal chelates, respectively. In vitro, all the compounds were screened for antimicrobial (against bacterial strains: S. aureus and E. coli; Fungal strain: A. niger), anti-diabetic and anti-inflammatory activity with their obtained IC₅₀ values and compared with Acarbose and Aspirin standard drugs. Bioactivities of azomethine containing free ligand (L), their Schiff base complexes and ternary metal chelates were compared to each other. Free Schiff base (L) was found most potent for all selective bioactivities compared to their all-metal complexes, except Ni (II) Schiff base complex showed excellent activity against C. albicans.

A series of organic sulfur-functionalized trans-platinum(II) bis(alkenylarylalkynyl) complexes, having one anisolylthio group with general formula trans-[(PEt₃)₂Pt{C≡C–Ar–CH=CH(SC₆H₄–OCH₃)}₂], (2a-2d), (Ar = phenylene/biphenylene/2,5-dimethylphenylene/2,5-dimethoxyphenylene) was synthesized in excellent yields. All the new platinum(II) complexes have been fully characterized by physico-chemical and spectroscopic methods. Photophysical properties of the complexes were studied by absorption and emission spectroscopy. The lowest energy absorption band for the complexes, in the UV/Vis spectra, in THF solution, at room temperature, 2a-2d was observed in the range 355–391 nm, which depend on the spacers in the acetylide ligand e.g., the absorption of 2d is red shifted to 391 nm for the donor (OCH₃) substituents in phenyl spacer. These absorptions originated predominantly from π–π*orbitals of acetylide ligand with significant contribution from the platinum dπ orbital as evident from the HOMO and LUMO, obtained from TD-DFT calculations. Fluorescence was observed in all complexes at room temperature in the range 400–428 nm with PLQY of 2–5%. At 77 k, the complexes 2a-2b only exhibited phosphorescence in the range 579–585 nm, but there is no phosphorescence at ambient temperature.

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Two new paramagnetic hybrid cobalt(II)-hexaborate(2-)-based semi-organic complexes: (2A3MP)₂[Co{κ³O–B₆O₇(OH)₆}₂].2H₂O (1) and (2A4MP)₂[Co{κ³O–B₆O₇(OH)₆}₂].2H₂O (2) (2A3MP = 2-amino-3-methylpyridinium, 2A4MP = 2-amino-4-methylpyridinium) have been obtained and characterized by X-ray diffraction, FT-IR, TG–DTA, optical and magnetic measurements. X-ray diffraction revealed two isostructural compounds based on Co(II) complexes of bis(κ³O-donor hexaborate(2-)) ligands, [Co{κ³O–B₆O₇(OH)₆}₂]²⁻, differing only in the organic counter cation. The hydrated oxidopolyborate anions are extensively H-bounded to form 3D-porous supramolecular anionic frameworks. In both 1 and 2 isostructures, 2A3MP and 2A4MP cations are present in the created voids of the inorganic frameworks through a set of H-bonds with 58.5 and 60.5% H…O/O…H intercontact contributions, respectively, for 1 and 2 as confirmed by Hirshfeld surfaces analysis. The optical band gap of Co(II) complexes ranges between 2.72 and 2.82 eV. Both compounds exhibited well-resolved paramagnetic properties with magnetic susceptibility values ranging between 0.9552 cm³ mol⁻¹ (at 2 K) and 0.0088 cm³ mol⁻¹ (at 300 K), typical of octahedral Co(II) complexes.