GREEN CHEMISTRY
·
2016
·Vol. 18
·期 21
·5900-5914
·
IF 8.506
Shuangtao Yin,Jin Li,Hui Zhang
A series of honeycomb-like hierarchical hollow nanostructured magnetic catalysts, γ-Fe2O3@M3Al-LDH@Au25-x (x represents determined mass of gold in wt%), have been successfully fabricated by modified electrostatic adsorption of water-soluble captopril-capped Au25 nanoclusters (Au25Capt18) on pre-prepared magnetic supports, Fe3O4@M3Al-LDH (M = Ni, Mg, or Cu/Mg (0.5/2.5), LDH: layered double hydroxide) followed by proper calcination. The characterization results show that the low Au-loading samples, γ-Fe2O3@Ni3Al-LDH@Au25-x (x = 0.053, 0.11), show nearly atomically precise Au25 nanoclusters (Au25NCs) (∼1.4 ± 0.3–1.9 ± 0.6 nm) dispersed on the surface of the Ni3Al-LDH shell, while the catalysts, γ-Fe2O3@M3Al-LDH@Au25-x (x ∼ 0.2), display slightly aggregated Au25NCs on the LDH shell with sizes of ∼3.0 ± 1.3, 3.3 ± 1.2, and 4.2 ± 1.5 nm for Ni-, Mg-, and CuMg-based catalysts, respectively, related to varied synergy between Au25NCs and magnetic LDH supports at slightly higher Au loadings. All the γ-Fe2O3@M3Al-LDH@Au25-x catalysts exhibit much higher catalytic activity for the oxidation of 1-phenylethanol under atmospheric O2, without basic additives, in toluene than Fe3O4@Mg3Al-LDH@Au prepared by a traditional deposition–precipitation method. The catalyst, γ-Fe2O3@Ni3Al-LDH@Au25-x, presents even higher alcohol oxidation activity than γ-Fe2O3@Mg3Al-LDH@Au25-0.21 and γ-Fe2O3@Cu0.5Mg2.5Al-LDH@Au25-0.2 and, particularly, γ-Fe2O3@Ni3Al-LDH@Au25-0.053 exhibits the highest activity (TOF: 112 498 h−1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions and can be applied for a variety of alcohols, this being mainly attributed to its nearly atomically precise Au25NCs and remarkable Au25NCs–LDH–magnetic core three-phase synergistic interaction, along with its abundant Ni-OH sites. Moreover, γ-Fe2O3@Ni3Al-LDH@Au25-0.053 can be easily separated, by simply applying an external magnetic field, and reused for more than ten runs without significant loss of activity, giving the magnetic catalysts long-term stability. These observations make Fe3O4@LDH a universal green platform to support other noble or non-precious metal nanoparticles by using a metal nanocluster precursor method to construct desired metal-loaded ecofriendly catalysts that can be applied in a broad range of heterogeneous catalysis processes.
研究领域:
催化化学
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材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2017
·Vol. 35
·期 5
·567-571
·
IF 1.852
Man-bo Li,Shi-kai Tian,Zhikun Wu
Tuning the nanoclusters’ compositions and structures is critical for the performance improvement of nanoclusters. Herein, a well-known Au 25 (SCH 2 CH 2 Ph) 18 (Au 25 for short) nanocluster has been transformed to a rare cadmium doped gold nanocluster [Au 13 Cd 2 (PPh 3 ) 6 (SC 2 H 4 Ph) 6 (NO 3 ) 2 ] 2 Cd(NO 3 ) 4 (Au 26 Cd 5 for short) by peeling and doping. Although Au 25 exhibits no catalytic activity toward A 3 -coupling reaction under the investigated conditions, the novel cadmium doped gold nanocluster Au 26 Cd 5 shows high catalytic activity, as well as good recyclability and substrate tolerance for the same reaction. The high catalytic activity is attributed to the cooperation between the exerted cadmium atoms and the neighbor gold atoms on the surface of Au 13 icosahedron. This work has important implication for the tuning of nanoclusters’ compositions and structures targeting the improvement of catalytic performance by some unusual but effective strategies.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Chemical Science
·
2025
·
IF 7.4
Yuping Chen,Guoqing Bian,Zhikun Wu,Qing Tang
Ligand exchange is an important strategy to functionalize metal nanoclusters (NCs) for enhanced properties. Thiolates and alkynyls have been widely used for NC protection, however, the possibility for alkynyl-for-thiolate exchange as well as the kinetics for the ligand exchange process have remained largely unexplored. Herein, we reported the first kinetic investigation into the alkynyl-for-thiolate exchange through the reaction of thiolated Au25(SR)18 with the incoming alkynyl ligands. Interestingly, our simulations revealed the electronic and steric effect of alkynyl ligands, and the precursor cluster’s charge state collectively govern the exchange efficiency and regioselectivity. Notably, the alkynyl-for-thiolate exchange is highly facile when reacting with the nucleophilic lithium or gold(I)−alkynyl complex (Au(C≡CR) or Li(C≡CR)), but fails when using HC≡CR as the exchange ligand. The Au(C≡CPh) complex exhibits charge-state-dependent exchange at the S1 or S2 position, whereas the sterically bulky Au(C≡CtBu) complex decelerates the exchange kinetics and universally targets the S1 position as the exchange product. By contrast, the lithium-alkynyl complex (Li(C≡CPh) or Li(C≡CtBu)) preferentially leads to the S1' exchange isomer, driven by the ionic Li−C bonding that enhances the C≡C π*-electron density and alkynyl nucleophilicity. Our predictions are further validated by the ligand exchange experiments between phenyl ethanethiol (PET) protected [Au25(PET)18]− and Au(C≡CtBu). The electrospray ionization mass spectra (ESI-MS) unambiguously confirms the successful substitution of about 4, 5 and 6 PET ligands by the −C≡CtBu ligand, and the absorption spectrum is drastically changed upon the alkynyl exchange. This work establishes important atomic-level understanding of the alkynyl-for-thiolate exchange mechanism, offering a convenient strategy of realizing alkynyl and thiolate co-protected gold clusters under mild conditions.
研究领域:
纳米材料
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物理化学
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团簇科学
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材料化学
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表面化学
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产品关联
DOI
PubMed
高影响因子
Journal of Materials Chemistry B
·
2022
·Vol. 10
·期 25
·4789-4799
·
IF 7.571
Hao Chen,Yongxin Jiang,Tingting Xu,Jiangmei Xu,Jun Yu,Zhaoyou Chu,Yechun Jiang,Yongbo Song,Hua Wang,Haisheng Qian
The persistent progression of synovial inflammation and cartilage destruction contributes to the crosstalk between pro-inflammatory macrophages and activated fibroblast-like synoviocytes (FLSs) in a synovial microenvironment. In this work, structurally well-defined Au25 nanoclusters were synthesized to induce phenotypic polarization of pro-inflammatory macrophages and apoptosis of activated FLSs for enhanced rheumatoid arthritis treatment. These ultra-small nanoclusters significantly modulated phenotypic polarization of a pro-inflammatory M1 phenotype to an anti-inflammatory phenotype M2 for relieving inflammation. Additionally, Au25 nanoclusters can efficiently activate reactive oxygen species (ROS)-mediated apoptotic signaling pathways by inactivating thioredoxin reductase (TrxR), resulting in imbalance of the cellular redox homeostasis and initiation of FLS apoptosis. In an adjuvant-induced arthritis rat model, Au25 nanoclusters efficiently ameliorated the hyperplasia of the synovium and reduced inflammatory cell infiltration with negligible side effects. This study provided a new insight into Au nanoclusters for treating rheumatoid arthritis.
研究领域:
纳米技术
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免疫学
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药理学
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风湿病学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）