One-pot,solvent-free and efficient synthesis of 2,4,6-triarylpyridines catalyzed by nano-titania-supported sulfonic acid as a novel heterogeneous nanocatalyst

Nano titania-supported sulfonic acid (n-TSA) has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2, 4, 6-triarylpyridines through one-pot three-component reaction of acetophenones, aryl aldehydes and ammonium acetate. This reported method illustrates several advantages such as environmental friendliness reaction conditions, simplicity, short reaction time, easy work up, reusability of catalyst and high yields of the products. One new compound is reported too. Furthermore, the catalyst could be recycled after a simple work-up, and reused at least six times without substantial reduction in its catalytic activity.     

Emission and performance analysis of DI diesel engines fueled by biodiesel blends via CFD simulation of spray combustion and different spray breakup models: a numerical study

Journal of Thermal Analysis and Calorimetry - In the current study, computational fluid dynamics code was used to perform 3D simulation of mixture formation and combustion of biodiesel fuel spray...     

Cyanide Biodegradation by Trichoderma harzianum and Cyanide Hydratase Network Analysis

Cyanide is a poisonous and dangerous chemical that binds to metals in metalloenzymes, especially cytochrome C oxidase and, thus, interferes with their functionalities. Different pathways and enzymes are involved during cyanide biodegradation, and cyanide hydratase is one of the enzymes that is involved in such a process. In this study, cyanide resistance and cyanide degradation were studied using 24 fungal strains in order to find the strain with the best capacity for cyanide bioremediation. To confirm the capacity of the tested strains, cyano-bioremediation and the presence of the gene that is responsible for the cyanide detoxification was assessed. From the tested organisms, Trichoderma harzianum (T. harzianum) had a significant capability to resist and degrade cyanide at a 15 mM concentration, where it achieved an efficiency of 75% in 7 days. The gene network analysis of enzymes that are involved in cyanide degradation revealed the involvement of cyanide hydratase, dipeptidase, carbon–nitrogen hydrolase-like protein, and ATP adenylyltransferase. This study revealed that T. harzianum was more efficient in degrading cyanide than the other tested fungal organisms, and molecular analysis confirmed the experimental observations.     

CuI‐functionalized halloysite nanoclay as an efficient heterogeneous catalyst for promoting click reactions: Combination of experimental and computational chemistry

Amine‐functionalized halloysite nanotubes (HNTs‐2 N) were prepared and further modified by introduction of salicylaldehyde and formation of imine functionality (HNTs‐2 N‐Sal). The latter was subsequently used for immobilization of CuI and formation of CuI@HNTs‐2 N‐Sal, which could effectively promote click reactions of terminal alkynes, sodium azide and α‐haloketones or alkyl halides in aqueous media and under mild reaction conditions to afford 1,2,3‐triazoles in relatively short reaction times. Notably, the catalyst could be recycled in up to six reaction runs with negligible loss of catalytic activity and CuI leaching. Also, the geometry of CuI adsorption on the modified HNTs surface was explored by molecular simulation with density functional theory. Furthermore, topographic steric maps of possible coordination modes were obtained using the recently released SambVca2 web application tool. Based on obtained results, a catalytic site with superior performance was suggested.     

Ultrasonic and bio‐assisted synthesis of Ag@HNTs‐T as a novel heterogeneous catalyst for the green synthesis of propargylamines: A combination of experimental and computational study

A novel heterogeneous catalyst is prepared through functionalization of halloysite nanotube with 1H‐1,2,3‐triazole‐5‐methanol and subsequent immobilization of silver nanoparticles through bio‐assisted approach using Arctiumplatylepis extract. The resulting catalyst, Ag@HNTs‐T, was characterized by using SEM/EDX, BET, XRD, FTIR, ICP‐AES, TGA, DTGA and elemental mapping analysis. Moreover, we computationally assessed metal‐ligand interactions in Ag@HNTs‐T complex model to interpret the immobilization behavior of silver nanoparticles on HNTs surface via quantum chemistry computations. The catalytic activity of the catalyst was studied for the synthesis of propargylamines via A³ and KA² coupling reactions under ultrasonic irradiation. The results demonstrated that Ag@HNTs‐T could efficiently promote these reactions to furnish the corresponding products in high yields and short reaction times. The study of the recyclability of the catalyst and Ag(0) leaching confirmed that the catalyst was recyclability up to four reaction runs with slight Ag(0) leaching.     

Combination of polymer and halloysite chemistry for development of a novel catalytic hybrid system

Research on Chemical Intermediates - A covalent hybrid of halloysite-poly(methyl methacrylate-co-maleic anhydride) was prepared and applied for the immobilization of Pd nanoparticles. The hybrid...     

Preparation of Ag‐doped g‐C3N4 Nano Sheet Decorated Magnetic γ‐Fe2O3@SiO2 Core–Shell Hollow Spheres through a Novel Hydrothermal Procedure: Investigation of the Catalytic activity for A3, KA2 Coupling Reactions and [3 + 2] Cycloaddition

Taking advantageous of both g‐C₃N₄ and magnetic core‐shell hollow spheres, for the first time a heterogeneous and magnetically separable hybrid system was prepared through a novel and simple hydrothermal procedure and used for immobilization of bio‐synthesized Ag(0) nanoparticles. The hybrid system was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA, DTGA, ICP‐AES, BET and elemental mapping analysis. The catalytic utility of the obtained system, h‐Fe₂O₃@SiO₂/g‐C₃N₄/Ag, for promoting ultrasonic‐assisted A³, KA² coupling reactions and [3 + 2] cycloaddition has been confirmed. The results established that the catalyst could efficiently catalyze the reaction to afford the corresponding products in high yields in short reaction times. The reusability study confirmed that the catalyst could be recovered and reused for at least five reaction runs with only slight loss of the catalytic activity. The hot filtration test also proved low silver leaching, indicating the heterogeneous nature of the catalysis.     

Flavones and rosmarinic acid from Salvia limbata

The genus Salvia (Lamiaceae) contains more than 50 shrub species in Iran, and Salvia limbata C.A. Meyer grows widely in the north and central parts of the country. Six flavones and rosmarinic acid were isolated from the ethyl acetate and methanol extracts of the flowered aerial parts of S. limbata collected from Semnan province. The separation process was carried out using several chromatographic methods. Structural elucidation was based on NMR data, in comparison with those reported in the literature. The isolated compounds were identified as ladanein (1), salvigenin (2), luteolin 7-methyl ether (3), cirsiliol (4), eupatorin (5), luteolin 7-O-glucoside (6) and rosmarinic acid (7). Some of these flavonoids have been reported to show antibacterial and cytotoxic activities.     

Bio‐assisted synthesized Ag(0) nanoparticles immobilized on SBA‐15/cyclodextrin nanosponge adduct: Efficient heterogeneous catalyst for the ultrasonic‐assisted synthesis of benzopyranopyrimidines

For the first time, SBA‐15/cyclodextrin nanosponge adduct was synthesized through reaction of Cl‐functionalized SBA‐15 and amine‐functionalized cyclodextrin nanosponge (CDNS). This adduct, which benefits from features of both SBA‐15 and CDNS, was then used for immobilization of Ag(0) nanoparticles which were prepared and capped using a bio‐based approach. Ag@CDNS–SBA‐15 was applied as a heterogeneous catalyst for promoting the three‐component reaction of benzaldehydes, 4‐hydroxycoumarin and urea or thiourea under ultrasonic irradiation to furnish benzopyranopyrimidines. The reaction variables were optimized using response surface methodology. The catalytic activity of Ag@CDNS–SBA‐15 was higher than those of Ag@CDNS, Ag@SBA‐15 and Ag@SBA‐15 + CDNS, confirming the contribution of both components to catalysis as well as a synergistic effect between CDNS and SBA‐15. The role of CDNS was to accommodate the substrates and bring them to the vicinity of the Ag(0) nanoparticles. Notably the catalyst was reusable and could be recovered and reused for up to four reaction runs with slight Ag(0) leaching and loss of catalytic activity.