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Magnetic nanoparticles are efficient catalytic systems for various reactions because of their high efficiency and easy separation. Amongst magnetic nanoparticles, copper ferrite (CuFe2O4 NPs) is one of the different types of ferrites, which is widely used in catalytic reactions because of its magnetic properties. On the other hand, deep eutectic solvents (DESs) consisting of a hydrogen bond acceptor component and a hydrogen bond donor component have recently attracted the attention of many researchers as green solvents. ChCl-urea is considered a green DES that has been reported several times to carry out chemical reactions. In recent years, research on the synthesis of 2-thioaryl-benzothiazoles and 2-thioaryl-benzoxazoles (compounds containing C-S aryls and benzothiazoles and benzoxazoles scaffolds) has become an attractive challenge in organic chemistry. In this research, we report the synthesis of 2-thio-benzothiazoles and 2-thioaryl-benzoxazoles by CuFe2O4 NPs in ChCl-urea as an efficient nanocatalyst. These compounds were synthesized via a one-pot, three-component coupling reaction of benzoxazoles or benzothiazoles with aryl iodides and S8 as a sulfur source in the presence of KOAc as a base. [ABSTRACT FROM AUTHOR]

Research on synthetic methods for the preparation of oxazoles is an important issue among synthetic chemists because oxazole derivatives are structural subunits of various natural active products and are valuable synthetic and pharmaceutical precursors. In this research work, we constructed CuBr supported on surface of magnetic Fe3O4 nanoparticles modified with 6-(aminomethyl)nicotinic acid [Fe3O4@AMNA-CuBr nanocomposite] and evaluated its catalytic activity for the preparation of highly substituted oxazoles through one-pot three-component reactions of diphenylacetylene derivatives with aryl nitriles and water in PEG as the solvent. The results shown that the Fe3O4@AMNA-CuBr catalyst was used 8 times without significant decrease in catalytic activity. XRD and TEM analysis confirmed that the structure and morphology that the Fe3O4@AMNA-CuBr catalyst did not change after 8 runs. [ABSTRACT FROM AUTHOR]

Given that thermoelastic damping (TED) is one of the main causes of energy dissipation in miniaturized structures, calculation of its exact amount is of particular importance in the design of such elements. Considering three-dimensional (3D) heat transfer along with the scale effect on both mechanical and thermal areas is one of the decisive factors in the more rigorous modeling of TED in small-sized resonators. This paper exploits the modified couple stress theory (MCST) and dual-phase-lag (DPL) heat conduction model to establish an analytical TED relation for rectangular micro/nanoplate resonators with 3D heat conduction. At the start, the non-Fourier heat equation corresponding to 3D DPL model is derived. Then, the solution of temperature distribution is determined by employing infinite trigonometric series. Moreover, the scale-dependent frequency of the system is presented in the context of MCST. Eventually, with the help of entropy generation (EG) method, an analytical TED expression considering 3D heat conduction is established. The precision of the presented solution is examined by comparing it with a simpler model available in the literature. By choosing two common types of boundary conditions, i.e. fully-clamped (CCCC) and fully-simply (SSSS) supported plates, the influence of various factors on TED changes is comprehensively investigated in simulation section. According to the outcomes, in plates with a lower ratio of length and width to thickness, the dimension considered for heat conduction model has a noticeable impact on the variations of TED. [ABSTRACT FROM AUTHOR]

In this study, Co3O4 nanoparticles were used as nanocatalyst for two different series of nitrogen-containing heterocyclic compounds, including pyrrole (Pyo) derivatives and pyrano [2, 3-c]pyrazole (Pya[2, 3-c]Pyz) derivatives. In the synthesis of derivatives, using 15 mol% and 10 mol% of the catalyst for Pyo derivatives and Pya[2, 3-c]Pyz derivatives, respectively, an efficiency between 83% and 96%, were observed. In addition, novel derivatives of Pyo and Pya[2,3- c]Pyz were synthesized and their structures were confirmed. In general, the advantages of using cobalt nanoparticles compared to previous reports include the synthesis of new derivatives, lower temperature used in the synthesis of derivatives, shorter synthesis time and high efficiency. The biological properties of the synthesized products, such as antibacterial, antifungal, and antioxidant properties, were tested and investigated. In antibacterial and antifungal tests, IZD, MIC, MBC, and MFC were measured and reported. In antioxidant activity, IC50 was calculated and reported. High reusability, green and environmentally friendly, synthesis of new derivatives and synthesis of products with higher efficiency and shorter time were the important benefits of using cobalt nanoparticles as a catalyst. In antioxidant tests, the IC50 for synthesized Pyo derivatives and Pya[2, 3-c] Pyz derivatives were between 12.2 and 13.71 μg/mL, and 16.18--17.75 μg/mL, respectively. In antimicrobial testes, the MIC for synthesized Pyo derivatives and Pya[2, 3-c]Pyz derivatives were between 2 and 4,096 μg/mL, and 2--2048 μg/mL, respectively. The results showed that the antioxidant property of Pyo derivatives were more than Pya[2, 3-c] Pyz derivatives, but the antimicrobial effect of Pya[2,3-c] Pyz derivatives were more than Pyo derivatives. The antioxidant results proved that the activity of Pyo derivatives and Pya[2, 3-c] Pyz derivatives does not depend on the substitutions of the derivatives and is close to each other. Therefore, based on this, a proposed mechanism for stability of DPPH by Pyo derivatives and Pya[2, 3-c] Pyz derivatives were suggested. Finally, based on the more stable resonance structures of Pyo derivatives, compared to Pya[2, 3-c] Pyz derivatives, its high antioxidant property was justified. Pya[2, 3-c] Pyz derivatives has two heterocyclic rings connected together pyrano and pyrazole, but Pyo derivatives has only one heterocyclic ring (pyrrole). So high antimicrobial property of Pya[2, 3-c] Pyz derivatives compared to Pyo derivatives can be attributed to having two bioactive heterocyclic rings. [ABSTRACT FROM AUTHOR]

Context: The potential of Ni-C72 and Ni-Al36P36 as effective catalysts for O3 decomposition is examined by LH and ER mechanisms. The activation barrier energy and Gibbs free energy of reaction steps for O3 decomposition on Ni-C72 and Ni-Al36P36 are calculated. The ∆Eformation of Ni-C72 and Ni-Al36P36 are negative values and these structures are stable nano-catalysts. The Ni atoms are catalytic positions to adsorb the O3 and other important species of O3 decomposition by LH and ER mechanisms. The Ni-Al36P36 for O3 decomposition has lower Eacivation and more negative ∆Greaction than Ni-C72. The Eacivation value of rate-determining step for O3 decomposition by LH mechanism is lower than ER mechanism. The Ni-C72 and Ni-Al36P36 can catalyze the reaction steps of O3 decomposition by LH and ER mechanisms. Methods: The structures of Ni-C72 and Ni-Al36P36 nanocages and their complexes with O3 and other important species of are optimized by PW91PW91/6–311 + G (2d, 2p) model and M06-2X/cc-pVQZ model in GAMESS software. The strcutures of nanocages and their complexes with important species of O3 decomposition by LH and ER mechanisms are optimized and their frequencies are calculated in order to demonstrate that these structures are real minima on the potential energy surface. [ABSTRACT FROM AUTHOR]