Department of Chemistry, School of Sciences, Alzahra University, Vanak, Tehran, Iran.
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 9177948974, Mashhad, Iran.
Sci Rep. 2022 Jul 14;12(1):12004. doi: 10.1038/s41598-022-16384-z.
Lanthanoid-containing polyoxometalates (Ln-POMs) have been developed as effective and robust catalysts due to their Lewis acid-base active sites including the oxygen-enriched surfaces of POM and the unique 4f. electron configuration of Ln. As an extension of our interest in Ln-POMs, a series of as-synthesized nanocatalysts K[Ln(BWO)] (Ln-BW, Ln = La, Ce, Nd, Sm, Gd, and Er) synthesized and fully characterized using different techniques. The Ln ion with a big ionic radius was chosen as the Lewis acid center which is sandwiched by two mono-lacunary Keggin [BWO] units to form Ln-containing sandwiched type cluster. Consequently, the catalytic activity of nanocatalysts with different Ln was examined in the synthesis of bioactive isatin derivatives and compared under the same optimized reaction conditions in terms of yields of obtained products, indicating the superiority of the nano-Gd-BW in the aforementioned simple one-pot reaction. The effects of different dosages of nanocatalyst, type of solvent, reaction time, and reaction temperature in this catalytic system were investigated and the best results were obtained in the presence of 10 mol% of nano-Gd-BW in water for 12 min at the reflux condition.
镧系元素多金属氧酸盐（Ln-POMs）因其具有Lewis 酸碱活性位，包括 POM 的富氧表面和 Ln 独特的 4f 电子构型，已被开发为有效且强大的催化剂。作为我们对 Ln-POMs 研究兴趣的延伸，我们合成并使用不同技术对一系列合成的纳米催化剂 K[Ln(BWO)]（Ln-BW，Ln = La、Ce、Nd、Sm、Gd 和 Er）进行了全面表征。选择具有较大离子半径的Ln 离子作为 Lewis 酸中心，由两个单缺位 Keggin [BWO] 单元夹在中间，形成含 Ln 的夹心型簇。因此，在相同的优化反应条件下，我们考察了不同 Ln 的纳米催化剂在生物活性靛红衍生物合成中的催化活性，并根据获得产物的产率进行了比较，表明纳米-Gd-BW 在上述简单的一锅法反应中具有优越性。我们还研究了不同纳米催化剂用量、溶剂种类、反应时间和反应温度对该催化体系的影响，结果表明，在水相中，纳米-Gd-BW 的最佳用量为 10mol%，反应时间为 12min，回流条件下反应效果最佳。
