Pd/AlO(OH): A Heterogeneous, Stable and Recyclable Catalyst for N-Arylation of Aniline Under Ligand-Free Aerobic Condition

EPS-mediated biosynthesis of nanoparticles by Bacillus stratosphericus A07, their characterization and potential application in azo dye degradation

Microbial exopolysaccharides (EPS) are biocompatible, biodegradable, and less toxic substances secreted outside the cell. They adsorb metal cations to its surface, making it another captivating property, which helps in stabilizing and biosynthesizing metal nanoparticles. Owing to these properties, we adopted bacterial EPS toward the green synthesis of nanoparticles and its application in the removal of azo dyes. Extracted EPS weighed 2.6 mg/mL from the most potential isolate A07 with 385 μg/mg of the carbohydrate content. The top three isolates were subjected to nanoparticle synthesis via the intracellular method and, by their extracted EPS, silver nanoparticles (AgNP) with the size around 87 nm were successfully produced by both methods mediated by the most potent isolate. The nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction studies, atomic force microscopy, and FT-IR analysis. The nanoparticles were employed for dye degradation of azo dyes, namely, Methyl Orange (MO) and Congo Red (CO). EPS-Ag NPs showed fair degradation capability determined by UV-Vis kinetic studies. The work suggests electron transfer from reducing agent to dye molecule mediated by nanoparticles, destroying the dye chromophore. This makes EPS-Ag NPs a suitable, cheap, and environment-friendly candidate for biodegradation of harmful azo dyes. The most potential isolate was identified as Bacillus stratosphericus by 16S rRNA sequencing and submitted to GenBank under the accession id MK968439.

Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry, i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.

The bibliography includes 350 references.

Development of Porous Cobalt-/Copper-Doped Carbon Nanohybrids Derived from Functionalized MOFs as Efficient Catalysts for the Ullmann Cross-Coupling Reaction: Insights into the Active Centers

Newly emerging poly-functional metal-organic frameworks (MOFs) have been proved to be a promising alternative method for the hard/soft template to generate different carbon-based heterostructures. Herein, we have synthesized a sulfonyl-amide-based MOF (TMU-81) with an exceptionally high concentration of functional groups, which can interact strongly with metal ions and utilized it as a double-template platform to fabricate versatile catalysts by remaining structural regularity. The preloaded copper ions resided in pores of TMU-81 not only play a significant role in pore-forming by in situ renovating into Cu nanoparticles via the pyrolysis process but also trigger the morphological transformations of the resultant metal/carbon hybrids. The morphology of the TMU-81 was tuned from truncated octahedron to cubic in cobalt-/copper-doped carbon nanohybrids (MC-81), and also the Brunauer-Emmett-Teller surface area increased significantly up to 1450 cm²/g. Benchmarks have been established for the performance of TMU-81, pyrolyzed TMU-81 (P-TMU-81), and MC-81s, as efficient and robust catalysts for the C-N cross-coupling reaction with aryl-halides and amines. The obtained MC-81 showed superior performance compared with pristine TMU-81 and pyrolyzed P-TMU-81. The catalysis performance is found to be closely dependent on the amount of preloaded Cu²⁺ ions in the MOFs. After 5 cycles, the catalysts were reusable without any significant loss of activity. Benefiting from the structural and compositional advantages, the present approach offers an intelligent way to synthesis and design of structurally complex MOF hybrid and derived functionalized systems.

Highly Efficient and Reusable Pd/AlO(OH) Catalyzed Synthesis of Acridinedione Derivatives

Background:

Synthesis of acridinedione derivatives via one-pot multi-component approaches using highly active and reusable Pd/AlO(OH) heterogenous catalyst was studied. This process provided a convenient method to obtain various acridinediones with potential biological activities. The reactions were performed in mild conditions such as low temperature and short reaction time with desirable yields.

Methods:

Commercially available Pd/AlO(OH) nanoparticles characterized by XRD and SEM methods were afforded for the synthesis of acridinedione derivatives with high yields. Crude products were analyzed by GC and 1H NMR. The reactions were completed within 1h at 40°C by the assistance of ultrasound system.

Results:

Optimization of reaction conditions is of critical case for successful synthesis. Solvent, temperature, time and amount of catalyst were studied. At the end of the experiments, the synthesis of 1 mmol of acridinedione was optimized by using 25 mg of Pd/AlO(OH) NPs, 3 ml of DMF for 60 min at 40°C in the ultrasound system. An experimental work to check the reusability of the catalyst was also studied. Pd/Al(O)OH catalyst in the first run was higher than that of the reused catalyst in the fifth run. ICP-OES analyses showed palladium leaching into the reaction medium was only 1.1% which is negligible. Nanocatalyst employed a high activity and good reusability.

Conclusion:

A convenient and versatile method was developed for the synthesis of acridinediones in a mild condition with absolute conversion and high yield using ultrasound system in the presence of nanocatalyst.