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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]

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]

In this study, the catalytic activity and potential of Co-C 72 , Co-Si 72 and Co-Al 36 N 36 nanocages for Nitrogen reduction reaction (N 2 -RR) via distal, alternating, enzymatic and mixed mechanisms are investigated by theoretical methods. Results indicated that the *NN-Co-nanocage → *NNH-Co-nanocage step for Nitrogen reduction reaction (N 2 -RR) is limiting step on Co-C 72 , Co-Si 72 and Co-Al 36 N 36 nanocages. Results indicated that the ΔG reaction of N 2 -RR on Co-Al 36 N 36 nanocage via distal, alternating, enzymatic and mixed mechanisms are more negative than Co-C 72 and Co-Si 72 nanocages. Finally, the Co-Al 36 N 36 can be proposed as acceptable catalysts for N 2 -RR via distal, alternating, enzymatic and mixed mechanisms with high performance by theoretical methods. [Display omitted] • Potential of Co-C 72 , Co-Si 72 and Co-Al 36 N 36 for N 2 -RR by possible mechanism are investigated by theoretical methods. • Co atoms of Co-C 72 , Co-Si 72 and Co-Al 36 N 36 are catalytic sites to adsorb the N 2 molecules by theoretical methods. • Al 36 N 36 has higher ability and capacity than Co-C 72 and Co-Si 72 to adsorb N 2 molecule by theoretical methods. • Co-Si 72 and Al 36 N 36 nanocages are proposed as effective catalysts for N 2 -RR by theoretical methods. • Co-Si 72 and Co-Al 36 N 36 nanocages have lower over-potential than metal catalysts for N 2 -RR by theoretical methods. In this study, the catalytic activity and potential of Co-C 72 , Co-Si 72 and Co-Al 36 N 36 nanocages for Nitrogen reduction reaction (N 2 -RR) via various mechanisms are investigated by theoretical models. Results shown that the unoccupied 3d orbitals of electrons of Co atoms of Co-C 72 , Co-Si 72 and Co-Al 36 N 36 nanocages have high potential to adsorb the pair of valence electrons of Nitrogen molecule (N 2). Results indicated that the *NN → *NNH step for Nitrogen reduction reaction (N 2 -RR) is limiting step on Co-C 72 , Co-Si 72 and Co-Al 36 N 36 nanocages. The ΔG reaction of N 2 -RR on Co-Al 36 N 36 nanocage via distal, alternating, enzymatic and mixed mechanisms are more negative than Co-C 72 and Co-Si 72 nanocages. The Co-Al 36 N 36 nanocage is proposed as effective catalyst for N 2 -RR by theoretical models. [ABSTRACT FROM AUTHOR]