3146-39-2Relevant academic research and scientific papers
Growth of Cu-BTC MOFs on dendrimer-like porous silica nanospheres for the catalytic aerobic epoxidation of olefins
Zhou, Zihao,Li, Xiujuan,Wang, Yulin,Luan, Yi,Li, Xiaoyu,Du, Xin
, p. 14350 - 14357 (2020/09/21)
The composition of metal-organic frameworks (MOFs) and porous carriers can be utilized for a variety of material applications. In this study, DPSNs@Cu-BTC nanocomposites are achieved utilizing Dendrimer-like Porous Silica Nanoparticles (DPSNs) as the support through a template-mediated self-assembly mechanism. The fabrication process is initiated from the controllable growth of Cu2O nanoparticles (NPs) in the center-radial porous channels of DPSNs, which forms DPSNs@Cu2O nanocomposites. Under the protection of DPSNs, the loaded Cu2O NPs gradually dissolved in the weak acid solution, thus providing copper ions to guide the formation and growth of Cu-BTC nanocrystals. Moreover, the Cu-BTC NPs were restricted in the center-radial porous channels of the DPSNs, thus resulting in small sizes and a uniform distribution. The formation of the DPSNs@Cu-BTC nanocomposites with adjustable amounts of Cu-BTC mainly depended on the amounts of Cu2O NPs loaded and the amount of organic ligands added. Furthermore, the nanocomposite exhibited high catalytic performance and good recyclability taking advantage of the uniform loading of small-sized Cu-BTC NPs in the accessible center-radial porous channels of the DPSNs. This new design of DPSNs@Cu-BTC provided a new approach for the synthesis of various MOF-based nanocomposites with improved performance.
Binuclear molybdenum Schiff-base complex: An efficient catalyst for the epoxidation of alkenes
Guo, Yingxiong,Xiao, Longqiang,Li, Pan,Zou, Wenhong,Zhang, Wenzhe,Hou, Linxi
, (2019/07/10)
Dimolybdenum Schiff-base complex (DMSBC) which contain O,N-bidentate ligand was synthesized and characterized. The complex can be used as a promising catalyst in the epoxidation of olefins with tert-butyl-hydroperoxide (TBHP) as oxidant. The catalytic activity of the DMSBC was optimized by adjusting various parameters. Epoxidation of olefins by DMSBC indicated that the catalyst exhibited superb catalytic activity with high conversions up to 99.6%, high selectivity up to 100%, and high turnover frequency (TOF) of 208 h?1. Kinetic analysis provided that epoxidation of cyclooctene by DMSBC possessed moderate activation energy (95.3 ± 2 kJ·mol?1). Furthermore, the calculated pre-exponential factor (A) proved that strong collisions probability take place in the reaction. Additionally, the recycle experiments demonstrated that DMSBC could be recovered and repeatedly applied.
A new Organopalladium compound containing four Iron (III) Porphyrins for the selective oxidation of alkanes/alkenes by t-BuOOH
Singh, Manoj Kumar,Bandyopadhyay, Debkumar
, p. 383 - 389 (2016/03/16)
Two iron(III) tetraphenyl porphyrin catalytic units are connected by an azo-link to form the dimeric compound A. The compound A was then reacted with Pd 2+ to make a tetrameric iron(III) porphyrin complex B with all four iron(III) catalytic sites open to the substrates and reactants. Both the compounds were characterized spectroscopically and the results of homogeneous oxidation of some alkanes and alkenes with t-BuOOH in presence of catalytic quantities of A and B have indicated remarkable improvement in selectivity and efficiency of A over the monomeric catalyst and B over A. [Figure not available: see fulltext.]
Fabrication of hierarchical composite microspheres of copper-doped Fe3O4@P4VP@ZIF-8 and their application in aerobic oxidation
Hou, Junying,Luan, Yi,Yu, Jie,Qi, Yue,Wang, Ge,Lu, Yunfeng
, p. 10127 - 10135 (2016/12/07)
Novel hierarchical magnetic composite microspheres of copper-doped Fe3O4@poly(4-vinylpyridine-co-divinylbenzene)@ZIF-8 (Cu-FPZ, Cu stands for copper doped) were successfully fabricated. The core-shell Fe3O4(PAA)@P4VP magnetic microspheres were first synthesized by a polymerization approach, in which the 4-vinylpyridine (4-VP) monomer interacted with a-COOH group of poly(acrylic acid) modified Fe3O4 by means of a hydrogen-bond interaction. Then Zn2+ was adsorbed on the surface of the P4VP shell, followed by the formation of a ZIF-8 porous shell with 2-methylimidazolate. Finally, nearly 5.45 wt% of copper content was incorporated with the ZIF-8 framework to form a magnetic core-shell copper-doped Fe3O4@P4VP@ZIF-8. The obtained copper-doped Fe3O4@P4VP@ZIF-8 catalyst was applied in the selective oxidation of alcohols and epoxidation of olefins using molecular oxygen as the oxidant. The results demonstrated that the magnetic core-shell copper-doped Fe3O4@P4VP@ZIF-8 catalyst showed better catalytic activity with significantly improved turnover number and turnover frequency (up to 8.25 h-1) than other copper MOFs. Furthermore, this heterogeneous catalyst could be cycled at least 15 times without significant loss of activity.
Immobilized V-MIL-101 on modified Fe3O4 nanoparticles as heterogeneous catalyst for epoxidation of allyl alcohols and alkenes
Farzaneh, Faezeh,Sadeghi, Yasaman
, p. 275 - 281 (2015/03/03)
As a new heterogeneous catalyst, Fe3O4 nanoparticles were prepared and modified with sodium silicate and (3-aminopropyl) trimethoxysilane (APTMS) followed by complexation with V-MIL-101 and designated as Fe3O4@SiO2@APTMS@VMIL-101. It was characterized using FTIR, TEM, and VSM techniques. The Fe3O4@SiO2@APTMS@VMIL-101 was found to successfully catalyze the epoxidation of allyl alcohols and alkenes with tert-butylhydroperoxide (TBHP) in moderate to high yields. The epoxidation of trans-stilbene, norbornen, cyclooctene, geraniol, trans-2-hexene-1ol and 1-octene-3-ol with 100% selectivity is promising. Investigation of the stability and reusability of Fe3O4@SiO2@APTMS@V-MIL-101 revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, ease of catalyst separation and recyclability of the solid catalyst are some advantages of this method.
Nanoscaled copper metal-organic framework (MOF) based on carboxylate ligands as an efficient heterogeneous catalyst for aerobic epoxidation of olefins and oxidation of benzylic and allylic alcohols
Qi, Yue,Luan, Yi,Yu, Jie,Peng, Xiong,Wang, Ge
, p. 1589 - 1597 (2015/01/30)
Aerobic epoxidation of olefins at a mild reaction temperature has been carried out by using nanomorphology of [Cu3(BTC)2 ] (BTC = 1,3,5-benzenetricarboxylate) as a high-performance catalyst through a simple synthetic strategy. An aromatic carboxylate ligand was employed to furnish a heterogeneous copper catalyst and also serves as the ligand for enhanced catalytic activities in the catalytic reaction. The utilization of a copper metal-organic framework catalyst was further extended to the aerobic oxidation of aromatic alcohols. The shape and size selectivity of the catalyst in olefin epoxidation and alcohol oxidation was investigated. Furthermore, the as-synthesized copper catalyst can be easily recovered and reused several times without leaching of active species or significant loss of activity.
Halogenated tetraphenyl porphyrin; Iodosylbenzene an efficient catalytic system for olefin epoxidation
Aggrawal, Dau D.,Bhat, Daisy
, p. 1123 - 1129 (2016/01/15)
Olefin epoxidation using o-phenyl and b-pyrrole substituted tetraphenyl porphyrin complexes of Fe(III) and Mn(III) as catalysts and yIodosylbenzene as oxidant was studied. Excellent yields of epoxide and secondary oxidation products were observed. Effect of pyridine, imadizole, sodium lauryl sulphate, and solvent variation was also studied. Effect of substituents on catalytic activity of the porphyrin complex is also explained. o-phenyl substituted complexes gave better yield of epoxide as compared to b-pyrrole substituted complexes.
Combined experimental and theoretical study on the reactivity of Compounds I and II in horseradish peroxidase biomimetics
Ji, Li,Franke, Alicja,Brindell, Malgorzata,Oszajca, Maria,Zahl, Achim,Van Eldik, Rudi
, p. 14437 - 14450 (2015/04/14)
For the exploration of the intrinsic reactivity of two key active species in the catalytic cycle of horseradish peroxidase (HRP), Compound I (HRP-I) and Compound II (HRP-II), we generated in situ [FeIV=O(TMP+?)(2-MeIm)] + and [FeIV=O(TMP)(2-MeIm)]0 (TMP = 5,10,15,20-tetramesitylporphyrin; 2-MeIm = 2-methylimidazole) as biomimetics for HRP-I and HRP-II, respectively. Their catalytic activities in epoxidation, hydrogen abstraction, and heteroatom oxidation reactions were studied in acetonitrile at -15 °C by utilizing rapid-scan UV/Vis spectroscopy. Comparison of the secondorder rate constants measured for the direct reactions of the HRP-I and HRP-II mimics with the selected substrates clearly confirmed the outstanding oxidizing capability of the HRP-I mimic, which is significantly higher than that of HRP-II. The experimental study was supported by computational modeling (DFT calculations) of the oxidation mechanism of the selected substrates with the involvement of quartet and doublet HRP-I mimics (2,4Cpd I) and the closed-shell triplet spin HRP-II model (3Cpd II) as oxidizing species. The significantly lower activation barriers calculated for the oxidation systems involving 2,4Cpd I than those found for 3Cpd II are in line with the much higher oxidizing efficiency of the HRP-I mimic proven in the experimental part of the study. In addition, the DFT calculations show that all three reaction types catalyzed by HRP-I occur on the doublet spin surface in an effectively concerted manner, whereas these reactions may proceed in a stepwise mechanism with the HRP-II mimic as oxidant. However, the high desaturation or oxygen rebound barriers during C-H bond activation processes by the HRP-II mimic predict a sufficient lifetime for the substrate radical formed through hydrogen abstraction. Thus, the theoretical calculations suggest that the dissociation of the substrate radical may be a more favorable pathway than desaturation or oxygen rebound processes. Importantly, depending on the electronic nature of the oxidizing species, that is, 2,4Cpd I or 3Cpd II, an interesting region-selective conversion phenomenon between sulfoxidation and H-atom abstraction was revealed in the course of the oxidation reaction of dimethylsulfide. The combined experimental and theoretical study on the elucidation of the intrinsic reactivity patterns of the HRP-I and HRP-II mimics provides a valuable tool for evaluating the particular role of the HRP active species in biological systems.
Hierarchical PS/PANI nanostructure supported Cu(ii) complexes: Facile synthesis and study of catalytic applications in aerobic oxidation
Yu, Jie,Luan, Yi,Qi, Yue,Hou, Junying,Dong, Wenjun,Yang, Mu,Wang, Ge
, p. 55028 - 55035 (2015/02/19)
Hierarchical heterogeneous copper catalysts were prepared by immobilization of a homogeneous copper(ii) complex on the surface of polystyrene/polyaniline (PS/PANI) microspheres with oriented PANI nanofibers. EDX element maps and XPS spectra indicated that Cu2+ ions strongly coordinated with PANI imine. PS/PANI@Cu(OSO2CF3)2 exhibited excellent catalytic activity for selective aerobic oxidation of alcohols and highly efficient aerobic epoxidation of alkenes under mild conditions. The supported copper(ii) catalyst maintained high levels of conversion and selectivity in these reactions after six cycles and showed good stability. This journal is
Rhodium acetate-catalyzed aerobic Mukaiyama epoxidation of alkenes
Shabashov, Dmitry,Doyle, Michael P.
supporting information, p. 10009 - 10013 (2013/11/06)
Mukaiyama epoxidation of alkenes under oxygen catalyzed by rhodium acetate with isobutyraldehyde as the reducing agent is as or more effective than previously reported procedures. A variety of alkenes, including terpenes and cholesterol derivatives, were oxidized. And high regioselectivity for monoepoxidation was observed with neryl, geranyl, and linalyl acetates.
