College of Chemistry and Chemical Engineering, Taishan University, Tai'an, 271021, Shandong, P. R. China.
Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry & Chemical Engineering, Liaocheng University, Liaocheng, 252059, Shandong, P. R. China.
Dalton Trans. 2021 Jul 27;50(29):10082-10091. doi: 10.1039/d1dt01413g.
By introducing 4-amino-1,2,4-triazole (4-NH2-trz), three new polyoxovanadate-based metal-organic frameworks (PMOFs) [Ni3(4-NH2-trz)6][V6O18]·3H2O (1), [Co3(4-NH2-trz)6][V6O18]·3H2O (2) and [Cu3OH(4-NH2-trz)3H2O][VO3]5·H2O (3) have been synthesized and thoroughly characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis and elemental analysis (EA). Among them, PMOFs 1 and 2 had similar structures containing [V6O18]6- clusters; however, PMOF 3 was isolated as a structure containing a [VO3]55- cluster when the amount of the 4-NH2-trz ligand was reduced to half with the other synthesis conditions being the same as those of PMOFs 1 and 2 except for the transition-metal chlorides. Furthermore, the negative charges of polyoxovanadate [V6O18]6- and [VO3]55- anions were balanced by trinuclear complex cations [Ni3(4-NH2-trz)6]6- for 1, [Co3(4-NH2-trz)6]6- for 2 and [Cu3OH(4-NH2-trz)3H2O]5- for 3, respectively. PMOFs 1-3 were further used as heterogeneous catalysts in the Knoevenagel condensation under solvent-free conditions and showed high catalytic activity. PMOF 1 showed moderate catalytic activities in the oxidation of various aromatic alcohols using H2O2 as an oxidant. Moreover, PMOF 1 could be reused at least three times without losing its activity.
通过引入 4-氨基-1,2,4-三唑（4-NH2-trz），合成了三种新型的基于多酸的金属有机骨架（PMOFs）[Ni3(4-NH2-trz)6][V6O18]·3H2O（1）、[Co3(4-NH2-trz)6][V6O18]·3H2O（2）和[Cu3OH(4-NH2-trz)3H2O][VO3]5·H2O（3），并通过单晶 X 射线衍射（SXRD）、粉末 X 射线衍射（PXRD）、红外光谱（FT-IR）、热重分析（TG）和元素分析（EA）进行了彻底的表征。其中，PMOFs 1 和 2 具有相似的结构，包含[V6O18]6-簇；然而，当 4-NH2-trz 配体的量减少到一半时，PMOF 3 被分离为一种结构，其中包含[VO3]55-簇，而其他合成条件与 PMOFs 1 和 2 相同，除了过渡金属氯化物。此外，多酸[V6O18]6-和[VO3]55-阴离子的负电荷由三核配合物阳离子[Ni3(4-NH2-trz)6]6-平衡对于 1，[Co3(4-NH2-trz)6]6-对于 2 和[Cu3OH(4-NH2-trz)3H2O]5-对于 3。PMOFs 1-3 进一步用作无溶剂条件下 Knoevenagel 缩合反应的非均相催化剂，表现出高催化活性。PMOF 1 在使用 H2O2 作为氧化剂氧化各种芳醇时表现出中等催化活性。此外，PMOF 1 至少可以重复使用三次而不会失去其活性。
