College of Chemistry and Material Science , Hebei Normal University , Shijiazhuang , Hebei 050024 , PR China.
Inorg Chem. 2018 Sep 17;57(18):11474-11481. doi: 10.1021/acs.inorgchem.8b01321. Epub 2018 Sep 4.
Three hybrid phosphomolybdates were successfully synthesized by hydrothermal method and characterized by a series of physicochemical analysis techniques. X-ray single-crystal structural analysis revealed that three compounds with the reductive polyanionic clusters (Mo) were wrapped by protonated organic component bpp cations (bpp = 1,3-bi(4-pyridyl)propane) through the complex supramolecular hydrogen bonding network. They also have similar molecular formulas: (Hbpp)[PbM(HO)]H{M[MoO(OH)(HPO)(PO)]}· nHO (M = Fe in 1, Zn in 2, n = 4; or M = Mn in 3, n = 6). The oxidation states of all Mo centers in these polyanions are in the form of +5, presenting clusters with the higher negative charge. The feature showed that they were easy to be modified by transition metal and organic moieties, so as to form a high-dimensional structure and produce functional materials with specific properties. Comparison of catalytic ability of three crystals to reduce Cr using formic acid as reductant, found that crystal 1 was effectively active to this redox reaction. The conversion of Cr can reach 99% after 120 min of heating in 55 °C water bath, and the conversion of above 95% can still be achieved after 5 recycles of applications.
三种混合磷钼酸盐通过水热法成功合成，并通过一系列物理化学分析技术进行了表征。X 射线单晶结构分析表明，三种化合物的还原多阴离子簇（Mo）被质子化的有机组分 bpp 阳离子（bpp=1,3-双（4-吡啶基）丙烷）包裹，通过复杂的超分子氢键网络。它们也具有相似的分子式：(Hbpp)[PbM(HO)]H{M[MoO(OH)(HPO)(PO)]}·nHO（M=Fe 在 1 中，Zn 在 2 中，n=4；或 M=Mn 在 3 中，n=6）。这些多阴离子中所有 Mo 中心的氧化态均为+5，呈现出具有更高负电荷的簇。这一特点表明它们很容易被过渡金属和有机基团修饰，从而形成具有特定性质的高维结构和功能性材料。比较三种晶体以甲酸作为还原剂还原 Cr 的催化能力，发现晶体 1 对该氧化还原反应具有有效活性。在 55°C 水浴中加热 120 分钟后，Cr 的转化率可达 99%，在 5 次应用循环后，转化率仍可达 95%以上。
