Mondal Bibhas, Kundu Mousumi, Mandal Siba Prasad, Saha Rajat, Roy Ujjal Kanti, Roychowdhury Anirban, Das Dipankar
Department of Chemistry, Kazi Nazrul University, Asansol 713340, India.
Department of Chemistry, NIT-Durgapur, Durgapur 713209, India.
ACS Omega. 2019 Aug 16;4(9):13845-13852. doi: 10.1021/acsomega.9b01477. eCollection 2019 Aug 27.
Heterogeneous green catalysis by using magnetically separable nanometal-oxide catalysts has become a subject of prime focus recently. PXRD (powder X-ray diffraction), FESEM (field emission scanning electron microscopy), and HRTEM (high-resolution tunneling electron microscopy) with IR and Raman spectroscopy are applied to analyze the structural and microstructural properties of nanosized (∼15.3 nm) CuFeO synthesized by both sonochemical and mechanochemical processes. The sonochemical process provides a better uniformity of sizes of the nanoparticles (NPs). Rietveld refinement with the PXRD pattern reveals the inverse spinel-like architecture of CuFeO NPs. The Raman spectra also indicate the phase purity of the synthesized material. The static magnetic measurements are performed at different magnetic fields and temperature ranges from 300 to 5 K, which confirms the existence of the ferrimagnetic phase mixed with some finer superparamagnetic (SPM) nanophases within the sample. Unsaturated magnetization is observed even at an applied 5 T magnetic field for the presence of spin-canting nature in the partially inverted copper ferrite phases at the surfaces of the nanoparticles. Now, these coupled magnetic CuFeO NPs are used as a heterogeneous catalyst for three-component Huisgen 1,3-dipolar cycloaddition click reaction in aqueous media. By this catalyst system, we were able to couple alkyl halide, epoxide, or boronic acid with alkynes efficiently to furnish 1,4-disubstituted 1,2,3-triazoles in excellent yields within very short reaction time. The test for heterogeneity, reusability, and reproducibility of the catalyst has also been performed successfully without prominent decrease in yield up to the fifth cycle.
利用可磁分离的纳米金属氧化物催化剂进行多相绿色催化近来已成为主要关注的课题。采用粉末X射线衍射（PXRD）、场发射扫描电子显微镜（FESEM）、高分辨率隧道电子显微镜（HRTEM）以及红外和拉曼光谱来分析通过声化学和机械化学过程合成的纳米尺寸（约15.3 nm）的CuFeO的结构和微观结构性质。声化学过程使纳米颗粒（NPs）的尺寸具有更好的均匀性。对PXRD图谱进行Rietveld精修揭示了CuFeO NPs的反尖晶石状结构。拉曼光谱也表明了合成材料的相纯度。在300至5 K的不同磁场和温度范围内进行静态磁性测量，证实了样品中存在与一些更细的超顺磁性（SPM）纳米相混合的亚铁磁相。由于纳米颗粒表面部分反转的铜铁氧体相中存在自旋倾斜性质，即使在施加5 T磁场时也观察到不饱和磁化。现在，这些耦合磁性CuFeO NPs被用作水介质中三组分Huisgen 1,3 - 偶极环加成点击反应的多相催化剂。通过该催化剂体系，我们能够使卤代烷、环氧化物或硼酸与炔烃高效偶联，在非常短的反应时间内以优异的产率得到1,4 - 二取代的1,2,3 - 三唑。还成功进行了催化剂的多相性、可重复使用性和可再现性测试，直至第五次循环产率均无明显下降。
