Synthesis, Structure, And Properities Of Basket-like Phosphomolybdate

Basket-liked polyoxometalate（POMs） is an important part of polyacid chemistry. Since 2004, the first case of basket compound was reported, the research progress of the compounds is very slow, which may be due to the intermediates of the compounds is not stable., leading to their very difficult in solution segregation. The study found that the compounds are mixed valence heteropoly blue and are widely used in electrochemistry, catalytic and photocatalytic, which has become a hot research topic.In this paper, eleven new basket-type phosphomolybdates were designed and hydrothermally synthesized by adjusting the proportion of raw materials, reaction temperature, adding different transition metal salt and different organic ligands. By elemental analysis and TG analysis, molecular formula of compounds were identified as:（H4pytp）2[SrìP₆Mo₁₈O73]·4H2O（1）,（H2pyttz）8[{Mn（H2pyttz）（H2O）3}2{SrìP₆Mo₁₈O73}]2·16H2O（2）, [{Zn（H3pyttz）（H2O）3}2{SrìP₆Mo₁₈O73}]·18H2O（3）, [{Mn（H2O）2}2{SrìP₆Mo₁₈O73}]·2H3O（4）,（H2imi）2[{Cu（H2O）2}{SrìP₆Mo₁₈O73}]·6H2O（5）,（H2bimbt）2[{Sr（H2O）3}{SrìP₆Mo₁₈O73}]（6）, {Cu（H2O）3}[{Cu（Hbimbt）}{Sr（H2O）3}{SrìP₆Mo₁₈O73}]2·H2O（7）,（H3pytp）（H2pyttz）2[{Fe（H2O）4}{SrìP₆Mo₁₈O73}]·5H2O（8）,（H3bimb）3[{Fe（H2O）4}[{Na（H2O）2}{SrìP₆Mo₁₈O73}2]]·12H3O（9）,（H2pyttz）2[{Cd（H2O）4}{Cd（H2O）3（H3pyttz）}{SrìP₆Mo₁₈O73}]·9H2O（10）,（pr）2[{Ca（H2O）}{Cd（H2O）}[{Sr（H2O）}{Cd（H2O）}{SrìP₆Mo₁₈O73}][{Sr（H2O）}{SrìP₆Mo₁₈O73}]]·7H2O（11）（pytp = 4’-（3’’-pyridyl）-2,4’:6’,4’-Terpyridine, pyttz = 3-（pyrazin-2-yl）-5-（1H-1,2,4-triazol-3-yl）-1,2,4-triazolyl, imi = imidazole, bimbt = 1,4-Bis（imidazo-1-lyl）bu- tane, bimb = 1,4- Bis（benzoimidazo-1-lyl）benzene, pr = pyrroles）. The structure was characterized via infrared（IR） spectroscopy, ultraviolet-visible light（UV-vis） spectroscopy, X-ray photoelectron spectroscopy（XPS）, and single-crystal X-ray diffraction（XRD） and other means.Cyclic voltammograms studies have shown that such compounds exhibit very good catalytic effect on the reduction of nitrite and hydrogen peroxide, and against oxidation of the ascorbic acid, which indicats that these basket type POM have bifunctional electrocatalytic activity, these type basket of phosphomolybdic acid salt, with functions of double electric catalytic activity. In addition, these basket type phosphomolybdates as catalyst has the very good catalytic effect on the degradation of dual azo dyesmethylene blue（MB） under the irradiation of ultraviolet light. Results show that degradation rate of MB is as high as 98.5% within 30 min, the lowest also reached 95.3%. Compared with other classic POMs, basket has high catalytic efficiency, short degradation time, easy to recycling, reusable, and long life of the catalyst, which are promising photocatalytic materials.