Copper complex with N-,O- architecture grafted graphene oxide nanosheet as a heterogeneous catalyst for Suzuki cross coupling reaction

Efficient Suzuki-Miyaura cross-coupling reaction by loading trace Pd nanoparticles onto copper-complex-derived Cu/C-700 solid support

The development of efficient carbon-carbon cross-coupling catalysts with low noble metal amounts attracts much attention recently. Herein, a Cu/C-700/Pd nanocomposite is obtained by loading trace Pd²⁺ onto carbon support derived from a novel mononuclear copper complex, {[Cu(POP)₂(Phen)₂]BF₄}. The as-prepared nanomaterial features the facial structure of highly dispersed copper phosphide nanoparticles as well as Pd nanoparticles via neighboring Cu-Pd sites. The Cu/C-700/Pd nanocomposite shows excellent catalytic activity (99.73%) and selectivity in Suzuki-Miyaura cross-coupling reaction, at trace Pd loading (0.43 mol%). Compared with the reported palladium nano catalysts, its advantages are proved. The appealing gateway to this stable, innovative and recyclability, Cu/C-700/Pd nanostructure recommends its beneficial utilization in carbon-carbon coupling and other environmentally friendly processes.

Magnetic composite of γ-Fe2O3 hollow sphere and palladium doped nitrogen-rich mesoporous carbon as a recoverable catalyst for C-C coupling reactions

In this article, palladated-magnetic nitrogen doped porous carbon was prepared from nano magnetic γ-Fe2O3 hollow sphere (h-Fe2O3) with high specific surface area and pore volume. To the purpose, initially h-Fe2O3 was prepared and covered with glucose via hydrothermal treatment with subsequent polymerization of organic shell. The polymerization of melamine-resorcinol-formaldehyde (MRF) was achieved in the presence of Cl-functionalized glucose coated h-Fe2O3 (h-Fe2O3@glu-MRF). Next, the prepared magnetic core-shell hollow sphere was palladated followed by carbonization to yield Pd@h-Fe2O3@C introducing more pores in its structure. The resulted compound, Pd@h-Fe2O3@C, was fully characterized, showing that carbonization process expressively increased the specific surface area. The resulted Pd@h-Fe2O3@C was successfully used for promoting C-C coupling reactions under mild reaction conditions as a heterogeneous catalyst and its activity was compared with some prepared control catalysts. This novel catalyst was magnetically separated simply by a magnet bar and recycled and reused at least in five consecutive runs, without considerable loss of its activity. It is note mentioning that, high recyclability with low Pd leaching are another gains of this protocol.

Two Schiff-base Complexes of Copper and Zirconium Oxide Fabricated on Magnetic Nanoparticles as Practical and Recyclable Catalysts in C-C Coupling Reaction

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Fe3O4 magnetic nanoparticles (MNPs) were prepared via a chemical co-precipitation method. Then, the surface of Fe3O4 MNPs was modified by (3-Chloropropyl)trimethoxysilane and then two Schiff-base complexes of zirconium oxide and copper were stabilized on modified Fe3O4 MNPs. These catalysts were characterized using SEM, EDS, WDX, FTIR, XRD, TGA, VSM and AAS techniques. The catalytic activity of these catalysts was described in the carbon-carbon coupling reaction. VSM analysis of these catalysts indicate the high magnetic performance, therefor these catalysts can be recovered by an external magnet and reused for several times without missing in the amount of catalysts. Reusability, excellent yields and high TON values indicate the high efficiency of these catalysts. Leaching of these catalysts was studied by AAS which leaching of copper or zirconium was not observed. Also, the stability of these catalysts was confirmed by characterization of recovered catalysts and comparing with fresh catalysts.

A recyclable heterogeneous nanocatalyst of copper-grafted natural asphalt sulfonate (NAS@Cu): characterization, synthesis and application in the Suzuki–Miyaura coupling reaction

NAS@Cu has synthesis simplicity given the availability of natural materials and has advantages such as being eco-friendly, high reactivity and recyclability.

Long-term impact of heavy metals on the performance of biological wastewater treatment processes during shock-adaptation-restoration phases

The present work investigated the long-term (30 days of shock-adaptation and 60 days of restoration) impact of Cu²⁺, Hg²⁺ and Ag⁺ shock loading on the performance of biological wastewater treatment processes. Under the same inhibitory concentration (IC₁₅), Cu²⁺ had the most significant impact on the treatment efficiency. During the shock-adaptation phase, Ag⁺ led to up to 4 times of biopolymers generation compared to that of the blank one; Hg²⁺ inhibited the nitrification process but showed little influence on other parameters; Cu²⁺ and Ag⁺ inhibited the activity of sDHA completely and decreased the content of ATP significantly, as well they caused abnormal ROS generation and corresponding CAT and SOD increment. Till 60 days of restoration can the activity of enzymes be restored to the control level, which agreed well with the results of effluent quality. Cu²⁺ decreased the biodiversity of the sludge to a large extent, followed by Ag⁺ and Hg²⁺. At the phylum level, Verrucomicrobia was decreased nearly to zero after 30 days of Cu²⁺ shock. At the genera level, Zoogloea was almost vanished after 15 days of Cu²⁺ shock.