Dalton Transactions最新文献

Phosphaketenes are important versatile reagents in organophosphorus chemistry. We herein report on the synthesis of novel mono- and bis-phosphaketenes based on redox-active acenaphthene-1,2-diimine ligands (bian) and their reactions with bian-gallylene and a trityl radical. The interaction of diiodide gallium(III) [(Ar^BIG-bian)GaI₂] (Ar^BIG-bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene) with two equivalents of sodium phosphaethynolate [Na(PCO)(diox)_0.5] gives the first paramagnetic phosphaketene [(Ar^BIG-bian)Ga(PCO)₂] (1). Reaction of 1 with gallylene [(Ar^BIG-bian)Ga] leads to phosphaketene [(Ar^BIG-bian)Ga(PCO)] (2). Gallium phosphaketene [(Ar^BIG-bian)Ga(Py)(PCO)] (3) is formed as a result of the interaction between diimine Ar^BIG-bian and excess gallium metal in the presence of gallium chloride in pyridine and a subsequent metathesis reaction with sodium phosphaethynolate. The addition of a trityl radical to 3 produces a sterically hindered alkyl complex [(Ar^BIG-bian)Ga(CPh₃)] (4). New compounds 1–4 have been characterized by ESR (1) and NMR (2–4) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The electronic structures of 1–4 and reaction thermodynamics were studied by DFT calculations.

A comprehensive computational exploration of the copper-catalysed umpolung-enabled three-component-coupling type electrophilic carboamination of cyclopropenes with arylboronic esters and a prototype aminating electrophile is reported. By examining plausible mechanistic scenarios advanced before for crucial elementary steps together with scrutinising performance-degrading pathways, we were able to replace previous hypotheses with a computationally verified mechanistic proposal. It comprises stepwise transmetalation of {P^P}Cu^I butoxide with Ph-Bnpg arylboronate to deliver the phenylcopper nucleophile. The distinct reactivity of cyclopropene's strained CC linkage renders arylcupration particularly rapid and irreversible, thereby almost completely disabling the rival performance-degrading formation of undesirable arylamines. The aminating electrophile then approaches the thus generated cyclopropylcopper, which triggers electrophilic amination to afford {P^P}Cu^I benzoate with the release of the 2-arylcyclopropylamine product. Umpolung-enabled amination favourably evolves through a two-step inner-sphere S_N2-type oxidative displacement/N–C bond generating a reductive elimination sequence via an intervening formal {P^P}Cu^III alkyl amido carboxylate intermediate. Conversion of {P^P}Cu^I benzoate, which represents the catalyst resting state, into the catalytically competent phenylcopper favours a multi-step salt metathesis/transmetalation sequence to involve the {P^P}Cu^I butoxide. The DFT-derived defining barrier for the turnover-limiting transmetalation aligns well with reported catalyst performance data. Spatial demands of the cyclopropene's substituents are found to be crucial for achieving a high degree of diastereoselectivity through diastereoselectivity-directing phenylcupration. While suitable electronic and steric modulation of the cyclopropene leaves the catalytic performance virtually unchanged, an electron-poor arylboronate is likely to enhance the catalytic outcome.

High-performance aqueous zinc-ion batteries (AZIBs) are regarded as a promising candidate for viable energy storage solutions. Exploring suitable cathodes with excellent electrochemical properties plays an important role in this field. Spinel ZnV₂O₄ has been employed as a potential cathode for AZIBs. However, its sluggish electrochemical kinetics impose restrictions on its further development. Hence, Al³⁺ is introduced into the ZnV₂O₄ lattice to accelerate Zn²⁺ diffusion, reduce electron transfer resistance and lengthen the cycling life. The structural analyses confirm that Al³⁺ is successfully doped into ZnV₂O₄ without any impurity and with improved structural stability. The electrochemical measurements and corresponding kinetic analyses reveal that the resulting Al-ZnV₂O₄ cathode exhibits significantly enhanced electrochemical performance and reaction kinetics. This is demonstrated by its excellent cycling stability (215 mA h g⁻¹ at 100 mA g⁻¹), remarkable rate capability (91 mA h g⁻¹ at 20 A g⁻¹), improved Zn²⁺ diffusion coefficient (10⁻¹⁵ to 10⁻¹³ cm² s⁻¹) and reduced charge transfer resistance (85 Ω).

In this work, a panel of twelve ruthenium(II) and osmium(II) derived N,O,O-tridentate complexes (1a–2f) with a variation of longer, branched and unbranched alkyl substituents was synthesized and characterized via NMR, HRMS, elemental analysis and X-ray diffraction analysis. Resilience to dissociation in biologically relevant solution was determined over 72 hours, revealing most stable complexes to derive from naphthoquinones bearing tert-butyl- and neopentyl-substituents. Osmium derived complexes were found to be generally more inert than their ruthenium counterparts. Cytotoxicity was examined, revealing IC₅₀ values in the nanomolar to lower micromolar range for derivatives 1a–2f in three human cancer lines and a typical pattern of selectivity for SW480 cells. Cellular accumulation correlated with in vitro cytotoxicity; however, longer and branched substituents did not improve the cellular accumulation. Cell cycle experiments showed consistent cell cycle inhibition in both SW480 and CH1/PA-1 cells for ruthenium-based compounds only. Indolamin-2,3-dioxygenase 1 (IDO1) inhibition assays in SKOV3 cells revealed significant inhibitory potential of Ru-Ethyl, in clear distinction to other ruthenium and osmium complexes.