Dalton Transactions最新文献

A series of lanthanide tetrakis-trifluoroacetates {(detaH₂)₂[La₂(tfa)₈]₂(CH₃CN)₅(H₂O)₂}_n and (detaH₂)_n[Ln(tfa)₄]_2n (Ln = Pr–Eu), mixed-ligand complexes [La(tfa)₃(CH₃CN)(H₂O)]_n, [Gd(tfa)₃(deta)₂](ⁱPrOH) and [Yb(tfa)₂(deta)₂](tfa), as well as detaH₂(tfa)₂ were isolated and characterized. All lanthanide tetrakis-trifluoroacetates contain two types of 1D anionic chains [Ln(tfa)₄]_nⁿ⁻ and cavities occupied by detaH₂²⁺ cations and solvating H₂O and CH₃CN molecules. The thermal behavior of (detaH₂)_n[Ln(tfa)₄]_2n in air is investigated by TGA, in situ VT-PXRD and total X-ray scattering with PDF analysis, and the formation of metal fluorides occurs upon heating to 300 °C. The application of solution with lanthanide trifluoroacetates and diethylenetriamine (deta) as precursors for chemical deposition of β-NaGdF₄:Er,Yb,Nd thin films is reported. The deposited β-NaGdF₄:Er,Yb,Nd thin film demonstrates up-conversion luminescence under 980 and 808 nm laser excitation.

Cyan-emitting phosphors are urgently needed to address the “cyan gap” in artificial full-spectrum lighting. In this research, a series of Sr_(2−y)Ba_yY₄La₄(SiO₄)₆O₂:xEu²⁺ (0.005 ≤ x ≤ 0.08, 0.0 ≤ y ≤ 2.0) phosphors with tunable luminescence was synthesized. Through cation regulation, the luminescence color of Sr_(2−y)Ba_yY₄La₄(SiO₄)₆O₂:xEu²⁺ can be adjusted from yellow to cyan. Crystal structure analysis revealed that Eu²⁺ ions simultaneously occupy [Sr1/Ba1Y1La1] and [Sr2/Ba2Y2La2] sites, resulting in multiple luminescence centers and a broadened emission spectrum. With increasing Ba²⁺ ion concentration, the PLE spectrum was red-shifted from 337 nm to 372 nm, and the excitation intensity in the violet region was significantly enhanced, making it more compatible with violet LED chips. Meanwhile, the PL spectrum was blue-shifted from 543 nm to 496 nm with increasing Ba²⁺ concentration, accompanied by an increase of about 10 times in the excitation and emission intensity. The optimized Ba₂Y₄La₄(SiO₄)₆O₂:0.02Eu²⁺ phosphor can be excited by violet light and emits bright cyan light effectively, which can be used to fill the “cyan gap”. Eventually, a series of white LED devices was manufactured by combining the as-prepared luminescence-tunable phosphors with commercial phosphors. Among them, the 410 nm violet LED chip-based WLED(Ba₂) device comprising Ba₂Y₄La₄(SiO₄)₆O₂:0.02Eu²⁺ exhibited the best electroluminescence performance, increasing the color rendering index from 82.0 to 98.6, verifying the compensation effect of the Ba₂Y₄La₄(SiO₄)₆O₂:Eu²⁺ phosphor on cyan light.

A series of small coinage metal(I) clusters has been selectively synthesized using 2-(diphenylphosphino)-1,10-phenanthroline (L), a new promising dimetal-binding P,N,N′-ligand (L). Its reaction with CuI yields the complex [Cu₂L₂(μ₂-I)]₂[Cu₂I₄], while the treatment of L with Au(tht)Cl/Ag⁺ or Au(tht)Cl/Cu⁺ systems leads to the assembly of [Au₂AgL₂Cl₂]⁺, [Au₂CuL₂Cl₂]⁺, [CuAuL₂]²⁺ and [AgAuL₂]²⁺ clusters. Theoretical analysis revealed pronounced intermetallic close shell interactions in these di- and trinuclear ensembles. At 298 K, the title compounds exhibit an orange and near-infrared (NIR) phosphorescence with lifetimes of 0.344–38 μs and quantum efficiencies of 1–21%. Theoretical considerations suggest a ³(M+L)LCT type for the observed phosphorescence. In addition, the above clusters exhibit a strong dose-dependent cytotoxic effect on A549, HepG2, Hep2 and MRC5 human cells with IC₅₀ values ranging from 1.26 to 11.1 μM.

To address the escalating demand for electrical energy, developing high-performance electrochemical energy storage materials is crucial. Metal oxides represent promising materials for high-energy-density supercapacitors. Among these materials, transition metal-based tungstates exhibit significantly enhanced electrical conductivity compared to pure oxides. However, their low inherent conductivity, restricted electrochemically active sites, significant volume expansion, lower capacity, and deprived cycling stability undermine their electrochemical properties. Herein, we synthesised an oxygen vacancy-enriched NiCoWO₄ electrode by a simple solid-state, solvent-free grinding process using NaBH₄. The Ov-NiCoWO₄ electrode displays an impressive capacitance of 703.66 F g⁻¹ at 1 A g⁻¹ and exceptional cycling stability with 87% retention over 2000 cycles at 7 A g⁻¹. This excellent performance is attributed to the oxygen vacancy in the Ov-NiCoWO₄ material, which increases the electron carrier density, accelerates electron transportation, enhances the active surface area, and boosts the redox reactivity of the material. In the as-prepared real-life supercapacitor configuration of Ov-NiCoWO₄//AC, a determined capacitance of 129.10 F g⁻¹ at 1 A g⁻¹ is achieved. Additionally, it exhibits an energy density of 37.699 W h kg⁻¹ with a power density of 724.98 W kg⁻¹, signifying exceptional performance. Furthermore, it maintains an impressive cycle life, retaining approximately 88.5% over 1000 cycles.

Ir–Ni alloys supported on SiO₂ have been reported to show high catalytic activity for styrene hydrogenation; however, precise control of compositions and sizes of the Ir–Ni alloys is difficult when conventional metal salts are used as precursors. Furthermore, the concomitant formation of unalloyed Ni nanoparticles disturbs quantitative discussion about Ir–Ni alloy compositions. We report herein a preparation method of Ir–Ni alloys with precisely controlled compositions on SiO₂ using Ni(NO₃)₂ and an Ir complex possessing CN⁻ ligands, [Ir(CN)₆]³⁻ or [Ir(ppy)₂(CN)₂]⁻ (ppy = 2-phenylpyridine), as precursors. The in situ formation of cyano-bridged coordination polymers involving Ir and Ni promotes the formation of Ir–Ni alloys, whose compositions are virtually the same as expected from the amounts of Ir and Ni used for the preparation, after heat treatment under H₂. The use of [Ir(ppy)₂(CN)₂]⁻ as the precursor resulted in the formation of smaller Ir–Ni alloy particles than those with [Ir(CN)₆]³⁻ related to the structures of the formed coordination polymers.

Polyoxometalate-based metal–organic frameworks (POMOFs) are highly effective heterogeneous catalysts that combine the catalytic activity of polyoxometalates (POMs) with the high surface area, tunable porosity, and structural diversity of MOFs. Nevertheless, there is still a lack of a general method to integrate POMs with various transition metal-based building units into POMOFs under mild conditions. In this work, we employed imine bonds to link amino-functionalized Anderson-type POMs with aldehyde-terminated divalent metal clusters, resulting in a series of isostructural POMOFs, M(II)-POMOFs (M = Zn, Co, Mg, or Mn). Furthermore, we used post-synthetic metal exchange and oxidation to transform Zn-POMOF into Fe(III)-POMOF with strong Lewis acidic Fe³⁺ sites. Notably, both the synthesis and post-synthetic modifications were performed under mild conditions (room temperature, acid-free), preventing the decomposition of the POMs. Compared to M(II)-POMOFs or MOFs without POMs, the combination of Lewis acidic Fe³⁺ and POMs enhanced its catalytic activity for CO₂ cycloaddition with epoxides, enabling efficient synthesis of cyclic carbonates. This versatile synthetic method could broaden the scope of POMOFs, extending their applications in catalysis and beyond.

Thomas C. Maier's group has reported a synergistic Ir/Ni catalysis method for the synthesis of C(sp²)–C(sp³) bonds through an amino radical transfer (ART) strategy to generate alkyl radicals. This work employed density functional theory (DFT) to investigate the reaction mechanism, including the redox mechanism of Ir complexes in the generation process of amino radicals, analyzed the role and rationale behind alkyl boronic esters becoming dominant reaction pathways in the ART process, and discussed the competitive reaction mechanisms between oxidative addition and radical capture during C(sp²)–C(sp³) cross-coupling with Ni complexes. Through this theoretical calculation study, we aim to provide a theoretical foundation for constructing key carbon radical intermediates using ART and Ni-complex catalyzed free-radical-involved C(sp²)–C(sp³) cross-coupling reactions.

A new unsymmetrical dinucleating phosphino pyridyl 1,8-naphthyridine ligand PNNN is reported. Reaction with CuCl gave the dicopper complex [Cu₂(μ-Cl)₂(PNNN)] (1). In contrast, complexation of [RuCl₂(cymene)]₂ yielded a monometallic species [RuCl(cymene)(PNNN)]Cl ([2]Cl) in which the Ru is bound to the κ²-N,N, rather than κ²-P,N, binding pocket. The selective formation of the monoruthenium complex [2]Cl enabled synthesis of heterobimetallic complexes [RuCuCl₃(cymene)(PNNN)] (3) and [RuCuCl₂(cymene)(PNNN)]₂[PF₆]₂ ([4]₂[PF₆]₂), which both exhibit κ¹-P coordination of Cu. Complexes 1 and [4]₂[PF₆]₂ exhibit reversible dearomatisation–aromatisation behaviour at the metal–ligand cooperative methylene site upon sequential treatment with base (KO^tBu) and acid (HCl). Notably, deprotonation of [4]₂[PF₆]₂ induces a shift in the coordination mode of Cu to κ²-P,N.

Although bimetallic noble nanostructures often possess high activity in nanocatalysis, their controllable fabrication, tunable catalytic activity, and easy separation remain significant challenges. In this study, an Fe₃O₄@AgPd/Polydopamine (Fe₃O₄@AgPd/PDA) nanosnowman loaded with an AgPd nanocage was designed by a one-step template-disposition-redox polymerization method. The AgPd nanocage endowed the product with high catalytic activity for the reduction of organic pollutants (4-NP, MO, MB). Interestingly, under near-infrared (NIR) light, the catalytic kinetics of the Fe₃O₄@AgPd/PDA nanosnowman on catalytic reduction of organic pollutants increased by 2.6, 1.57, and 5.45 times, respectively. The asymmetric nanostructure facilitated the separation of electron–hole pairs, promoted electron transfer, and accelerated the catalytic activity. Density functional theory (DFT) analysis indicated that the electron transfer between the AgPd alloy and the Fe₃O₄ nanosphere played a critical role on the high catalytic activity. Moreover, Fe₃O₄@AgPd/PDA also demonstrated excellent catalytic activity in the Heck carbon–carbon coupling reaction with a >95% conversion rate and >99% selectivity. Owing to the well-encapsulated PDA shell and outstanding magnetic properties, the Fe₃O₄@AgPd/PDA nanosnowman exhibited good cyclic catalytic activity. With its multi-mode catalysis, NIR-enhanced catalytic activity, and easy separation, the Fe₃O₄@AgPd/PDA nanosnowman exhibits great application potential in nanocatalysis.

Proton-conducting metal–organic frameworks (MOFs) have attracted tremendous attention for their promising application in proton-exchange membrane fuel cells. Water clusters play an extremely important role in the proton-conduction process and affect the proton conductivity of host materials. To date, the close-packing effect of water clusters within pores on proton conductivity due to the amorphous structure of commercial proton-exchange membranes is unclear. Herein, we prepared two crystalline MOFs containing different water clusters, namely, [Sm₂(fum)₃(H₂O)₄]·3H₂O (Sm-fum-7H₂O) and [Er₂(fum)₃(H₂O)₄]·8H₂O (Er-fum-12H₂O) (H₂fum = fumaric acid), and regulated their proton conductivities by changing the water clusters. As expected, Sm-fum-7H₂O showed a high proton conductivity of 6.89 × 10⁻⁴ S cm⁻¹ at 333 K and ∼97% RH because of the close packing of the water clusters within the pores triggered by a lanthanide contraction effect, outperforming that of Er-fum-12H₂O and some previously reported MOFs. Additionally, Sm-fum-7H₂O and Er-fum-12H₂O demonstrated high dielectric functions, reaching 2.22 × 10³ and 1.42 × 10⁵ at 10^2.5 Hz, respectively, making Er-fum-12H₂O a highly dielectric material. More importantly, broadband dielectric spectroscopy measurements indicated that there was a dielectric relaxation process in Er-fum-12H₂O with an activation energy of 0.59 eV. The present findings provide a better understanding of the crucial role of confined water clusters in proton conductivity and the novel phenomenon of the coexistence of proton conduction and dielectric relaxation in crystalline MOF materials.