Synthesis,Characterization,Properties Of [P₂Mo₅O₂₃]^6-/[Mo₇O₂₄]^6-/[?-Mo₈O₂₆]^4- Polyoxomolybdate Clusters Appended With Thiosemicarbazones

In recent years,the increasing contamination of water has raised a series of serious problems with industrial development.Among top priority pollutants,dyes represent an important class of environmental water pollutants.Water contaminated by dyes have many properties,such as deep color,high content of organic pollutants,complex composition,heavy metals and biological toxicity to biological degradation,dye photodegradation resistance,oxidation resistance,and containing many kinds of biological toxicity property of organic compounds.Synthetic dyes found in industrial effluents can create biological organism to weaken and cause a range of diseases,such as carcinogenesis,teratogenicity,mutagenicity,calling for the development of methods to destroy such compounds.Polyoxometalates?POMs?,as one kind of significant metal-oxide clusters with high negative charge and abundant topologies,have been proved to be a powerful means for treating contaminated water by organic dyes.Polyoxometalates also has a promising future in biomedicine,especially in cancers that threaten human life.Some of the heteropolyanion compounds are believed to be promising as highly efficient photocatalysts such as reported W₇O⁶₂₄–,W₁₀O⁴₃₂–,PW₁₂O³₄₀–,SiW₁₂O⁴₄₀–and P₂W₁₈O⁶₆₂–structures.In addition,POMs are superior for the removal of organic pollutants or transition metal ions from water,because they have excellent redox properties and their structures remain unchanged after a stepwise multi-electron redox process and POMs are also photostable and non-toxic.In particular,some POM-based organic–inorganic hybrids have excellent photocatalytic capacity on the degradation of organic pollutant for their appropriate optical band gaps and the nature of semiconductors.The introduction of organic ligands and transition metals into POMs can enrich their potential applications,such as in catalysis,non-linear optics,and electrical conductivity.Organic components can dramatically influence the microstructure and characteristic of hybrid materials.In addition,the synergic interactions between organic and inorganic components may benefit composite properties or even new characteristics.The metal ions[cobalt?Co?,copper?Cu?,iron?Fe?,manganese,nickel?Ni?and zinc?Zn?]have been widely used as the linking units to construct the hybrid compounds because of their relatively strong coordination abilities with both terminal oxygen?O?atoms of POMs and nitrogen?N?atoms of the organic ligands.Thus,a suitable combination of metal-salt,organic ligand,and POMs is essential for the design of POM-based hybrids with unique structures and properties.As the extension of the work,we endeavored to construct new inorganic–organic hybrid compounds based on transition metals,thiosemicarbazone and POMs,wherein the polyoxoanions have significant drug,catalytic characteristics,and thiosemicarbazone derivatives have excellent antitumor activity.Therefore,synthesis of the novel of inorganic-organic hybrid compounds has an important theoretical significance through exploring the synthesis of conditions.And potential catalytic activity in degradation of dyes and potential biological were further explored.Five new inorganic–organic hybrid compounds based on transition metals thiosemicarbazone and POM[Cu?H₂L¹??H₂O?]₂[(P₂Mo₅O₂₃)]·5H₂O?1?,[?H₂L²?₄]H₂[P₂Mo₅O₂₃]·5H₂O?2?,[Zn?HL³?₂]₂H₂[Mo₇O₂₄]·6H₂O?3?,[Ni?HL³??H₂O?₃]₂H₂[Mo₇O₂₄]·10H₂O?4?,[Fe?HL³??L³?]₂[?-Mo₈O₂₆]·N?CH₂CH₃?₃·5H₂O?5?have been synthesized and structurally characterized by a number of methods?elemental analysis,IR,UV-vis,TG,XRD and single crystal X-ray diffraction?.The adsorption and degradation properties of organic dye and drug activity were also investigated.In chapter 1,reactions of CuSO₄·5H₂O with 2-acetylpyrazine thiosemicarbazone?HL¹?,?NH₄?₂Mo₇O₂₄·4H₂O,HClO₄ and concentrated H₃PO₄ result in[Cu?H₂L¹??H₂O?]₂[(P₂Mo₅O₂₃)]·5H₂O?1?.Furthermore,reactionsofNa₂MoO₄·2H₂O,HClO₄andconcentratedH₃PO₄with pyridine-2-carboxaldehyde thiosemicarbazone?HL²?obtained compound[?H₂L²?₄]₂H₂[P₂Mo₅O₂₃]·5H₂O?2?.The catalytic degradation of methylene blue solution and rhodamine B solution,alkaline magenta solution,methyl orange solution were studied.The results shown that complex 2 has remarkable ability to degrade cationic dye such as methylene blue and rhodamine B,and it has a potential application prospect in water purification,organic pollutants degradation and environmental waste repair.Compounds 1–2 show different cytotoxicity against HL-7702 cells and SMMC-7721 cells.It is worth mentioning that 1 has a better cytotoxicity against SMMC-7721.In chapter 2,reactions of Zn?ClO₄?₂·6H₂O,Ni?ClO₄?₂·6H₂O with 2-acetylpyridine thiosemicarbazone?HL³?,Na₂MoO₄·2H₂O,NaOAc,trimethylamine,HOAc and concentrated HCl obtained[Zn?HL³?₂]₂H₂[Mo₇O₂₄]·6H₂O?3?,[Ni?HL³??H₂O?₃]₂H₂[Mo₇O₂₄]·10H₂O?4?,respectively.At the same time,the catalytic degradation of methylene blue solution and rhodamine B solution under dark condition was studied.The experimental results show that the complex has a certain degree of degradation of the two dyes.Compounds 3–4 show different cytotoxicity against HL-7702 cells and SMMC-7721 cells.It is worth mentioning that 3 has a better cytotoxicity against SMMC-7721.In chapter 3,reactions of FeCl₃·6H₂O with 2-acetylpyridine thiosemicarbazone?HL³?,Na₂MoO₄·2H₂O,NaOAc,and trimethylamine,HAc and concentrated HCl obtained[Fe?HL³??L³?]₂[Mo₈O₂₆]·N?CH₂CH₃?₃·5H₂O?5?.The experimental results show that the complex has a certain degree of degradation of methylene blue solution and rhodamine B,respectively.