- Silica iminopyridine-functionalized nanomaghemite enhances the oxygenation activity and durability of simple Co(II) salophen complex
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A novel magnetically recoverable catalyst was produced by coordinative attachment of Co(II) salophen complex to silica iminopyridine (SIPy)-functionalized-γ-Fe2O3 magnetic nanoparticles (SMNP?SIPy/Co(II) salophen). The vibration spectra and compositional data provided sufficient evidences for the structural integrity of as-prepared organic–inorganic nanohybrid. The magnetic nanocatalyst proved to be an efficient and selective heterogeneous catalyst for oxidation of different benzylic alcohols and featured higher catalytic activity and stability than that of homogenous counterpart. A TOF of 151 h?1 and TON of more than 322 were obtained for oxidation of 4-cholrobenzyl alcohol in this catalytic system. The supported catalyst could easily be recovered from the reaction mixture by an external magnetic field and reused for subsequent experiments with consistent catalytic activity.
- Jafarpour, Maasoumeh,Keikha, Narges,Rezaeifard, Abdolreza
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- Aldehydepropyl-functionalized mesostructured cellular foams: Efficient supports for immobilization of penicillin G acylase
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The aldehydepropyl-functionalized mesostructured cellular foams (CHO-MCFs) were prepared by post-synthetical functionalization of MCFs with trimethoxysilylpropanal (TMSP), and used as efficient supports for immobilization of penicillin G acylase (PGA). Th
- Gao, Zhenyuan,Zhan, Wangcheng,Guo, Yanglong,Wang, Yunsong,Guo, Yun,Lu, Guanzhong
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- Heterogeneous Fenton-like activity of novel metallosalophen magnetic nanocomposites: Significant anchoring group effect
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Two new pyridine and thiolate anchoring groups were prepared to functionalize γ-Fe2O3 nanoparticles for coordinative attachment of simple Fe(iii)- and Mn(iii)salophen complexes. Four new magnetically recoverable composites were characterized by several analytical techniques such as FT-IR, XRD, TGA, EDS compositional analysis and VSM to confirm superparamagnetic properties. TEM images revealed the nanostructure nature of composites with size ranging between 20 and 40 nm. A heterogeneous advanced oxidation process for degradation of some organic dyes as water pollution compounds using an aqueous solution of H2O2 were successfully exploited. Several key parameters including the metal center in the salophen complex, initial pH, catalyst dosage, H2O2 and dye concentration and temperature were investigated. A significant effect of the anchoring ligand on the degradation efficiency and catalyst stability was documented. The superior catalytic activity and particularly durability of the thiolate-based catalysts were demonstrated in comparison with their Py counterparts. Rate constants of 0.21, 0.17, 0.23 and 0.11 min-1 were obtained for degradation of rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and crystal violet (CV). Finally, a photoluminescence probing technology and radical scavenging measurements were carried out to elucidate the active species involved in the process.
- Keikha, Narges,Rezaeifard, Abdolreza,Jafarpour, Maasoumeh
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- Tandem Photocatalysis Protocol for Hydrogen Generation/Olefin Hydrogenation Using Pd-g-C3N4-Imine/TiO2Nanoparticles
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An unprecedented visible-light-driven photocatalytic system consisting of Pd nanoparticles stabilized on g-C3N4-imine-functionalized TiO2 nanoparticles was discovered for photoassisted hydrogen generation followed by olefin hydrogenation under mild conditions. The structural integrity of the as-synthesized photocatalyst was corroborated by Fourier transform infrared spectroscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-diffuse reflectance spectroscopy, Brunauer-Emmett-Teller measurements, and thermogravimetric analysis (TGA). Transmission electron microscopy and high-resolution scanning electron microscopy revealed the nanoscopic nature of the catalyst. The photocatalyst promoted several different transformations in a one-pot reaction sequence: hydrogen evolution through photocatalytic acceptorless formation of benzimidazoles as important therapeutic agents followed by visible-light-driven photocatalytic reduction of olefins with a high hydrogen utilization efficiency of up to 92% under mild conditions. A significant volume of H2 was produced under blue light-emitting diode (LED) irradiation during the selective formation of benzimidazole, while the selectivity reduced significantly under a Xe lamp or in the dark. The in situ-generated H2 could be activated by the as-prepared Pd-C3N4-imine/TiO2 photocatalyst to effectively hydrogenate olefins under mild conditions at appropriate time exposed to blue LED irradiation. The light-dependent photocatalytic performance of the title catalyst was assessed using action spectra by calculating the apparent quantum efficiency (AQE), which exhibited the maximum AQEs at 410 and 550 nm, at which the highest performance for styrene hydrogenation was obtained. The improved photoredox activity of the title nanohybrid could be caused by the synergistic effects of the heterojunction of carbon nitride-Pd on TiO2 nanoparticles evidenced by photoluminescence spectra and catalytic reactions. The catalyst proved to be air-stable, robust, recyclable, and very active in the absence of any undesirable additives and reducing agents. Thus, this work presents a new protocol for improving the photocatalytic properties of semiconducting materials for various photocatalytic applications under environmentally friendly conditions.
- Jafarpour, Maasoumeh,Feizpour, Fahimeh,Rezaeifard, Abdolreza,Pourmorteza, Narges,Breit, Bernhard
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p. 9484 - 9495
(2021/07/19)
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- Supramolecular photocatalyst of Palladium (II) Encapsulated within Dendrimer on TiO2 nanoparticles for Photo-induced Suzuki-Miyaura and Sonogashira Cross-Coupling reactions
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In this study, synthesis, characterization and catalytic performance of a novel supramolecular photocatalytic system including palladium (II) encapsulated within amine-terminated poly (triazine-triamine) dendrimer modified TiO2 nanoparticles (Pd (II) [PTATAD] @ TiO2) is presented. The obtained nanodendritic catalyst was characterized by FT-IR, ICP-AES, XPS, EDS, TEM, TGA and UV-DRS. The as-prepared nanodendritic catalyst was shown to be highly active, selective, and recyclable for the Suzuki–Miyaura and Sonogashira cross-coupling of a wide range of aryl halides including electron-rich and electron-poor and even aryl chlorides, affording the corresponding biaryl compounds in good to excellent yields under visible light irradiation. This study shows that visible light irradiation can drive the cross-coupling reactions on the Pd (II) [PTATAD] @ TiO2 under mild reaction conditions (27–30?°C) and no additional additives such as cocatalysts or phosphine ligands. So, we propose that the improved photoactivity predominantly benefits from the synergistic effects of Pd (II) amine-terminated poly (triazine-triamine) dendrimer on TiO2 nanoparticles that cause efficient separation and photogenerated electron–hole pairs and photoredox capability of nanocatalyst which all of these advantages due to the tuning of band gap of catalyst in the visible light region.
- Eskandari, Ameneh,Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Salimi, Mehri
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- A cobalt Schiff base complex on TiO2 nanoparticles as an effective synergistic nanocatalyst for aerobic C-H oxidation
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A novel visible light active TiO2 nanoparticle was produced by functionalization with a cobalt Schiff base complex under ultrasonic agitation. It was characterized by different techniques such as FT-IR, EDX, XPS, ICP-AES and TGA. The particle size of the synthesized nanocomposite was found to be in the range of 22-32 nm according to TEM images. A red-shift of the band-edge and a significant reduction of the band-gap (2.9 eV) were revealed by UV-DRS. The as-prepared nanocomposite demonstrated high oxidation activity and desired selectivity in the aerobic benzylic C-H oxidation of a structurally diverse set of alcohols and benzylic hydrocarbons. A synergistic effect of the cobalt Schiff base complex and TiO2 nanoparticles on the visible-light photocatalytic activity was explored. Spectral results and leaching experiments revealed that the heterogeneous catalyst preserved its structure after many reuses.
- Jafarpour, Maasoumeh,Kargar, Hossein,Rezaeifard, Abdolreza
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p. 25034 - 25046
(2016/03/22)
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- A zirconium Schiff base complex immobilized on starch-coated maghemite nanoparticles catalyzes heterogeneous condensation of 1,2-diamines with 1,2-dicarbonyl compounds
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A magnetically separable zirconium Schiff base nanocatalyst was synthesized under ultrasonic agitation. TEM images revealed a uniform spherical particle shape with average size of 10-14 nm for the as-prepared catalyst. The catalytic performance of ZrOL2@SMNP in the heterogeneous condensation of various 1,2-diamines and 1,2-dicarbonyls for the synthesis of heterocyclic compounds in ethanol has been explored.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza
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p. 205 - 211
(2016/02/20)
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- Starch-coated maghemite nanoparticles functionalized by a novel cobalt Schiff base complex catalyzes selective aerobic benzylic C-H oxidation
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In this work, a novel organosilicon aldehyde was prepared for the first time. It could be used as an appropriate linker by condensation with ethanol amine producing a new bidentate Schiff base ligand. Its cobalt complex was prepared under ultrasonic agitation and characterized by FT-IR and NMR spectra. Attachment to magnetic nanoparticles (γ-Fe2O3, MNP) coated with starch (SMNP) under ultrasonic irradiation produced a magnetically separable Schiff base catalyst. TEM images revealed a uniform spherical shape with average size of 12-15 nm for as-prepared catalyst. The selective benzylic C-H oxidation of a variety of benzylic alcohols as well as alkyl benzenes to the related carbonyl compounds using molecular oxygen in combination with n-hydroxyphthalimide (NHPI) were efficiently enhanced under the catalytic influence of title magnetically separable catalyst. The reactions proceeded smoothly under heterogeneous conditions and catalyst could be recovered and reused efficiently by an external magnetic field. The strong attachment of catalyst to magnetic support was confirmed by FT-IR spectra.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Yasinzadeh, Vahid,Kargar, Hossein
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p. 38460 - 38469
(2015/07/20)
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- Hydroformylation of alkenes having organosilicon substituents
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The hydroformylation of vinyltrimethylsilane catalyzed by transition metal complexes has been studied.Rh catalysts showed high activity with low regioselectivity.Addition of large excess of triphenylphosphine improved the regioselectivity to normal aldehyde.In contrast, a Co and a Pt catalyst gave exclusively n-aldehyde.Vinyltrimethoxysilane is also hydroformylated by transition metal catalysts.The factors of regioselectivity are discussed.
- Takeuchi, Ryo,Sato, Nobuhiro
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