APPLIED ORGANOMETALLIC CHEMISTRY
·
2026
·Vol. 40
·期 4
·e70549
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IF 4.3
Linjun Shao,Zheng Yin,Ke Long,Faliang Gou,Guiying Xing,Peng Yang,Xianman Zhang
Chitosan (CS) is a widely distributed and abundant biopolymer in nature. In this study, CS was blended with poly(methacrylic acid) (PMAA) to prepare stable chitosan composite nanofibers (CS/PMAA) via electrospinning, followed by annealing. The nanofibers were then functionalized through Schiff base reactions between CS amino groups and aldehydes and used to support palladium catalysts. Their catalytic performance was evaluated by the Heck reactions. Notably, the Pd 2+ ions anchored on the CS/PMAA nanofibers exhibited higher activity than those on the 2-pyridylimino-functionalized chitosan nanofibers (2PyCS/PMAA). In contrast, the Pd 0 species supported on the 2PyCS/PMAA nanofibers showed outstanding catalytic activity and remarkable reusability. HR-TEM was utilized to monitor the morphological changes and Pd 0 nanoparticle contents on the CS/PMAA and 2PyCS/PMAA nanofibers during reuse. Chelating interactions between the nanofibers and Pd 2+ ions were studied by FT-IR, adsorption distribution analysis, XRD, and HR-TEM. The strong nucleophilic affinity of Pd 2+ ions for the CS nanofibers was further verified by PALS. In conclusion, this work presents an effective and straightforward approach for preparing highly active and stable supported palladium catalysts.
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ACS Catalysis
·
2026
·
IF 13.6
Shi Zhanghan,Duan Fangyu,Liu Yafei,Zhang Xianwang,Song Guoquan,Yang Xiaomeng,Ma Qianli,Zhang Zongwu,Wu Dan,Xu Chunbao,Zhang Yongsheng
Cascade catalytic upgrading of biomass-derived furanic compounds to high-value cyclopentanone (CPO) and cyclopentanol (CPL) over metal–acid bifunctional catalysts has attracted considerable attention in sustainable chemistry. However, conventional bifunctional catalysts exhibit insufficient synergistic effects, primarily due to the lack of flexibility in tuning the ratio of acidic to hydrogenative active sites. Herein, we demonstrate that halogen (Br and Cl) modification of supported Cu catalysts significantly enhances both activity and selectivity in the aqueous-phase hydrogenative rearrangement of furfuryl alcohol (FOL), achieving a CPO yield of 94.4% and a CPL yield of 94.6%, respectively. Extensive characterizations reveal that the electronegative Br and Cl adatoms effectively modulate the electronic state of Cu nanoparticles, facilitating the formation of Lewis acidic Cu + sites on the catalyst surface. Mechanistic investigations disclose that Cu + sites mediate the rearrangement of FOL to 4-hydroxy-2-cyclopentenone (4-HCP), while adjacent Cu 0 sites catalyze the hydrogenation of 4-HCP to CPO, followed by its subsequent hydrogenation to CPL. Different binding strengths between Cu and halogens (I > Br > Cl) allow the regulation of the Cu + /Cu 0 ratio on the Cu surface, which in turn provides an effective way to control the reaction pathway. The developed halogen modification strategy not only offers great potential for the upgrading of biomass-derived furanics to cyclopentane derivatives but also presents a versatile strategy for regulating the surface Lewis acidity of metal catalysts, which is crucial for metal–acid bifunctional catalysis.
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MOLECULES
·
2023
·Vol. 28
·期 4
·1930
·
IF 4.6
Yanqi Ban,Hui Wang,Zixuan Xiao,Lishui Sun,Qingyan Pan,Yingjie Zhao
A carbon–carbon-linked, ultrathin, two-dimensional (2D) polymer film was prepared at the air/water interface through photochemically triggered [2 + 2] cycloaddition. The preorganization of the monomers on the water surface and the subsequent photo-polymerization led to the successful preparation of the ultrathin 2D polymer film. The obtained film is continuous, free standing, and has a large area (over 50 μm2). Transmission electron microscopy (TEM) and atomic force microscopy (AFM) give clear evidence of the ultrathin film morphology. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) indicate successful photo-induced [2 + 2] polymerization.Keywords:two-dimensional polymers;covalent organic frameworks;porous materials;interfacial synthesis;[2 + 2] cycloaddition;photochemistry
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Journal of Orthopaedic Surgery and Research
·
2023
·Vol. 18
·期 1
·1-15
·
IF 2.6
Sun Kai,Xue Yuman,Zhang Xin,Li Xiaodong,Zhao Jun,Xu Xilin,Zhang Xiaofeng,Yang Fubiao
Background The impaired blood supply to the bones is an important pathological feature of steroid-induced osteonecrosis of the femoral head (SIONFH). Danshen is a Chinese herb that shows therapeutic effects on SIONFH, but the effects of one of its major bioactive constituents, Tanshinone I (TsI), on SIONFH remain unknown. Here, we evaluated the effects of TsI on SIONFH, particularly focusing on its effects on angiogenesis, in in vivo and in vitro research. Methods SIONFH was induced in Sprague–Dawley rats by an intramuscular injection of methylprednisolone (40 mg/kg) in combination with an intraperitoneal injection of lipopolysaccharide (20 μg/kg). Morphological alterations of the femoral head were observed by dual-energy X-ray absorptiometry and HE staining. Western blot, qRT-PCR, and immunohistochemical/immunofluorescence staining were used to determine gene expression. Results TsI (10 mg/kg) alleviated bone loss and rescued the expression of angiogenesis-related molecules (CD31, VWF, VEGF, and VEGFR2) in the femoral heads of SIONFH rats. Notably, TsI rescued the down-regulated expression of SRY-box transcription factor 11 (SOX11) in CD31 + endothelial cells in the femoral heads of SIONFH rats. In vitro studies showed that TsI preserved the dexamethasone-harmed angiogenic property (migration and tube formation) of human umbilical vein cells (EA.hy926), suppressed dexamethasone-induced cell apoptosis, reduced pro-apoptotic proteins (cytosolic cytochrome C, Bax, and caspase 3/9) and increased anti-apoptotic protein Bcl-2, whereas silencing of SOX11 reversed these beneficial effects. Conclusions This study demonstrates that TsI alleviates SIONFH and promotes angiogenesis by regulating SOX11 expression. Our work would provide new evidence for the application of TsI to treat SIONFH. Graphical Abstract
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Molecular Catalysis
·
2022
·
IF 5.089
Jiaoyan Zhu,Tiefeng Xu,Panting Lu,Wenxing Chen,Wangyang Lu
Exploring sustainable catalysts for the transition-metal-catalyzed carbonylation and acknowledging the corresponding interior mechanism are of great interest. Herein, palladium supported spherical-like graphitic carbon nitride catalyst (Pd@s-CN) was prepared through a microwave-assisted approach, where s-CN with larger surface area was synthesized via an exfoliation and refluxing method. The spherical-like structure of s-CN can offer abundant space preventing the agglomeration of Pd and creating more active sites for carbonylation reaction. Notably, with iodobenzene as the substrate, Pd@s-CN achieved 92% yield of benzoic acid, and its performance was better than that of PdCl 2 and Pd/C catalysts. The effects of thermal, light source and catalyst structure were investigated. Ultimately, the reaction mechanism of photocatalytic carbonylation was proposed. This environmentally friendly photocatalytic carbonylation method is expected to provide a new idea for carbonylation and other related organic synthesis reactions.
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CATALYSIS TODAY
·
2022
·
IF 6.562
Mingyang Gao,Jiamin Wang,Weixiang Shang,Yuchao Chai,Weili Dai,Guangjun Wu,Naijia Guan,Landong Li
Suzuki-Miyaura cross-coupling reaction by homogeneous Pd complex is a powerful route to construct carbon-carbon bond and is now widely applied in the synthesis of functional organic compounds. Heterogeneous Pd catalysts are highly desired as alternatives to homogeneous ones due to their facile reusability and good compatibility. Herein, zeolite-encaged Pd particles, namely Pd@MFI, have been successfully prepared via an in-situ hydrothermal strategy and investigated as promising heterogeneous catalysts for Suzuki-Miyaura cross-coupling reactions. Characterization results demonstrate that high dispersed Pd particles with apparent sizes of 1–2 nm have been encaged in and efficiently stabilized by the matrix of MFI zeolite. The as-prepared Pd@MFI catalysts are active in the Suzuki-Miyaura coupling reaction between bromobenzene and phenylboronic acid, and the presence of basic sites adjacent to Pd sites are crucial to achieving high catalytic activity via effective cooperation. Pd@K-ZSM-5 can be optimized for the coupling between bromobenzene and phenylboronic acid and can catalyze the reaction with a low apparent activation energy value of 41.2 kJ/mol. Pd@K-ZSM-5 also shows good stability and can be recycled for at least five times without obvious loss in activity, demonstrating its great potential as a heterogeneous catalyst for Suzuki-Miyaura cross-coupling reactions. Encapsulation of metal species in zeolite matrix offers a big opportunity to the heterogenization of homogeneous metal catalysts for practical chemical transformations.
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INORGANIC CHEMISTRY COMMUNICATIONS
·
2023
·
IF 3.8
Miaomiao Li,Ying Li,Chunping Li,Tong Xu,Yinghui Sun,Jie Bai
Herein, the composite catalyst supported by Pd-Cu bimetal was prepared by hydrothermal synthesis method using carbon nanofibers anchored LZ-276 zeolite as carrier. The addition of Cu not only save cost but also realize the high dispersion of metal nanoparticles. Under the optimized reaction conditions, the catalyst exhibits excellent catalytic activity and cycle stability in the Suzuki-Miyaura reaction. The designed structure effectively improves the catalytic performance of metal nanoparticles catalyzed reaction, and would inhibit the leaching or aggregation of metal particles. The strategy of reducing the noble metals dosage by using non-noble metals to replace noble metals reduces the catalyst costs, and thus holding great promise for industrial application.
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JOURNAL OF MATERIALS SCIENCE
·
2023
·Vol. 58
·期 36
·14299-14314
·
IF 4.5
Xu Chenzhe,Qiu Yue,Wang Zheng,Gao Zifei,Liu Cai,Sun Yanran,Zhang Haitao,Ma Juanjuan,Liu Lin,Liu Chao,Tong Zhiwei
A facile one-step hydrothermal approach was proposed to fabricate Pd nanoparticles decorated Mg–Al layered double hydroxide nanosheets (denoted as Pd NPs/Mg–Al LDH composite), wherein polyvinylpyrrolidone (PVP) functioned as both a reductant and stabilizer. The resulting samples were characterized by XRD, SEM, TEM, XPS and BET techniques. The effect of synthetic parameters during the hydrothermal reaction including PVP dosage and temperature on the size and distribution of Pd NPs was investigated in details. Pd nanoparticles with an average particle size of 3.6 nm were uniformly supported onto Mg–Al LDH nanosheets under the optimal conditions. The obtained Pd NPs/Mg–Al LDH composite could serve as an efficient heterogeneous catalyst for the Heck reaction between iodobenzene and methyl acrylate, achieving a high yield of 95.8% within 60 min at 100 °C. Furthermore, Pd NPs/Mg–Al LDH was highly stable and reused 6 times without significant loss of its catalytic activity.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2021
·
IF 4.539
Dandan Lu,Keyang Yin,Ya Zhao,Zelin Gao,Nicolas Godbert,Hongmei Li,Hongguang Li,Jingcheng Hao
The synthesis of carbon dots (CDs) has attracted much attention in recent years. In this article, alkylated, blue-emitting CDs are prepared from dodecylamine through pyrolysis in differently substituted benzene solvents. The influences of the solvent on the size, yield and fluorescence quantum yield of the CDs have been investigated in detail. Overall, eight solvents were probed. It was found that the presence of halogen atom(s) in the solvent structure is beneficial for the production of the CDs, as seen from the poor yields of the CDs obtained in methylated benzenes. For the three mono-substituted halogenated benzenes with Cl, Br, I, as the atomic number of the halogen atom increases, hence increasing the resulting polarizability of the medium, the quantity of CDs obtained after pyrolysis also increases. For the two dichlorobenzenes probed, only the ortho-substitution is advantageous for the production of the CDs. The major quantity of CDs was obtained in iodobenzene (∼26 %) while the highest fluorescence quantum yield was observed for CDs prepared in bromobenzene (∼24 %), which is almost 4 times and 3 times that of the CDs developed in the old strategy using chlorobenzene as a solvent. Not only the change of the solvent tunes the photophysical properties of the CDs, it also alters their chemical structure. While the mono-substituted solvent is conducive to CDs with enriched C = O, the di-substituted one facilitates instead the formation of C-O. The possible interaction between the alkylamine and the solvent during pyrolysis was probed by adding lewis base and lewis acid to the system. Evidence of the occurrence of a process similar to Friedel-Crafts alkylation has been found. Our research illustrates new synthetic pathways and mechanism analysis for the preparation of CDs.
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ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Jin Li,Ying Song,Yanna Wang,Hui Zhang
A series of hierarchical nanosheet array-like Co–Al layered double hydroxides (LDHs)/reduced graphene oxide (rGO) hybrid supported ultrafine PdCu nanocluster (NC) catalysts m-PdCux/LDHs/rGO (x: Cu/Pd molar ratio of 1.5, 3.0, and 5.5; m: Pd loadings of ∼0.80, 0.40, 0.11, and 0.01 wt %) were assembled via an ultrasonic-assisted NaBH4 reduction–sol immobilization strategy. The as-obtained catalysts display ultrafine PdCu alloy NCs with sizes of ∼0.9–1.8 nm finely tuned by both Cu/Pd ratios and Pd loadings and mainly distributed on the edge sites of LDH nanosheets and part of LDHs–rGO junctions upon the unique hierarchical nanosheet array-like structure. Three catalysts 0.85-PdCu1.5/LDHs/rGO, 0.83-PdCu3.0/LDHs/rGO, and 0.80-PdCu5.5/LDHs/rGO exhibit excellent Heck reactivity for iodobenzene with styrene, of which the 0.83-PdCu3.0/LDHs/rGO shows the highest activity, much higher than Pd/LDHs/rGO and single LDHs or GO supported PdCu3.0 catalysts, attributed to the ultrafine PdCu3.0 NCs, the largest electron density of the Pd0 center, and the strongest PdCu3.0 NCs–LDHs–rGO three-phase synergistic effect. The lowest Pd-loading sample 0.01-PdCu3.0/LDHs/rGO shows an unprecedented turnover frequency of 210 000 h–1 (Pd dosage: 2 × 10–5 mol %) with the highest value so far, excellent adaptability for substrates, and reusability. The present work provides a versatile method for designing hierarchically structured ultrafine Pd–M alloy NC catalysts for varied catalysis processes.
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RSC Advances
·
2020
·Vol. 10
·期 70
·43175-43186
·
IF 3.119
Jinqiang Tan,Huamei Zhu,Shasha Cao,Sisi Chen,Yuanfu Tian,Dachuan Ding,Xuan Zheng,Chuanqun Hu,Tao Hu,Chonggang Wu
A poly(methyl methacrylate)-supported Pd0 nanocatalyst was successfully prepared from solution reaction of Pd(CH3COO)2 with a copolymer acid, poly(methyl methacrylate-ran-methacrylic acid) (MMA–MAA). The reaction was carried out in a benzene/methanol mixed solvent in the dark at room temperature (∼25 °C) in the absence of a typical chemical reductant. There was coordination between the Pd0 nanoclusters and MMA–MAA, resulting in Pd0 nanoclusters being stably and uniformly dispersed in the MMA–MAA matrix, with an average particle size of ∼2.5 ± 0.5 nm. Mechanistically, it can tentatively be proposed that PMMA-ionomerization of the Pd2+ ions produces intramolecular –2COO−–Pd2+ aggregate cross-links in the solution. On swelling of the chain-segments that are covalently bound via multiple C–C bonds, the resultant elastic forces cause instantaneous dissociation at the O–Pd coordination bonds to give transient bare (i.e., uncoordinated), highly-oxidative Pd2+ ions and H+-associative carboxylate groups, both of which rapidly scavenge electrons and protons, respectively, of the active α-H atoms abstracted from the methanol molecules of the solvent to make Pd0 nanoclusters supported by the re-formed MMA–MAA. The MMA–MAA acid copolymer, without itself undergoing any permanent chemical change, serves as a mechanical activator or catalyst for the mechanochemical reduction of Pd(CH3COO)2 under mild conditions. Compared with traditional Pd/C catalysts, this Pd0 nanocatalyst exhibited more excellent catalytic efficiency and reusability in the Heck reaction between iodobenzene and styrene, and it could be easily separated. The supported Pd0 nanocatalyst prepared using this novel and simple preparation method may display high-efficiency catalytic properties for other cross coupling reactions.
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CARBON
·
2020
·
IF 8.821
Kunlin Liu,Jiuzhou Wang,Ting Yang,Hong Wang,Chengyang Wang,Mingming Chen
Traditional synthesis methods of mesoporous carbon include hard templates (e.g., metal oxides , metal salts and mesoporous silica) and soft templates (e.g., surfactant and block copolymer). However, complicated and time-consuming procedures, high template costs, and harsh preparation conditions hinder the scale-up of these methods. Here, we report a simple and bottom-up strategy to synthesize mesoporous carbon by using the sodium-assisted carbonization of bromobenzene without additional templates added. Depending on the pyrolysis temperature, the obtained material with nanorod structures has a high surface area of 1902 m 2 g −1 , a large pore volume of 1.21 cm 3 g −1 and a high degree of graphitization . Meanwhile, the pore-forming mechanism of this strategy is explored and attributed to the “ in situ templating” effect of NaBr. The resultant material at 800 °C shows considerable rate performance, long lifetime and high power density. Additionally, the versatility and feasibility of the technique are validated via carbonization of six halogenated aromatic hydrocarbons by three alkali metals . Compared with lithium and potassium , sodium has better pore-forming effect and the obtained products possess a high surface area (1450–2100 m 2 g −1 ) and a large pore volume (1.1–1.6 cm 3 g −1 ). Furthermore, these mesoporous carbons show high adsorption capacity on dye macromolecules.
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