دو ترکیبات هیبریدی آلی- غیر آلی مبتنی بر POM : ترکیب، ساختارها، خواص مغناطیسی، تجزیه نوری و جذب انتخابی رنگ های آلی Two novel POM-based inorganic–organic hybrid compounds: synthesis, structures, magnetic properties, photodegradation and selective absorption of organic dyes

Polyoxometalates (POMs) are a kind of inorganic metal-oxide clusters that are assembled by early transition metal MOx polyhedra via sharing corners, edges and/or faces, and have abundant topologies and compositions, acid/base tunability and diverse electronic and photochemical properties. So far, a huge number of polyoxometalates have been synthesized and applied widely in fields of catalysis, medicine, electronics, magnetism and optics.1–۵ Recently, a new arising research topic in this field is the use of POMs as inorganic building blocks to construct inorganic–organic hybrid materials with various metal–organic coordination fragments. From the structural point of view, the polyoxometalate anions in these hybrids, can be either connected as guests/templates/counter ions through noncovalent interactions,1a,b or coordinated to metal atoms as inorganic ligands by covalent bonds.1e,f Therefore, the POM-supported hybrid materials combine the advantages of inorganic polyoxometalates and the functionalities of organic components, which make them attractive for many new potential applications ranging from gas storage, chemical separation and catalysis to ion exchange reactions. Besides Keggin heteropolyoxometalates in the big family of POMs, [Mo8O26] 4− octamolybdates are also very easily prepared or in situ formed from reaction precursors under hydrothermal conditions and controlled pH values. Furthermore, according to the different numbers and arrangement of MoO4, MoO5, and MoO6 polyhedra, at least nine types of octamolybdate isomers (i.e. α-, β-, γ-, δ-, ε-, ζ-, η-, θ- and ι-[Mo8O26] 4−) have  been reported so far.6–۸ These octamolybdate isomers exhibit rather good coordination abilities with various metal ions and show certain self-assembly abilities to form infinite inorganic chains.9 As a result, octamolybdates and their derivative species have been used widely as important inorganic building units to construct host–guest structures10 and inorganic– organic hybrid materials.8,11 To date, remarkable hybrid materials based on isolated iso- or heteropolyoxometalates have been reported, however, examples of inorganic–organic hybrid materials based on 1D chains or 2D layers of polyoxometalates are still very rare,12 indicating a research area still in its infancy, and an arduous challenge for POM chemists to rationally design and synthesize POM-supported inorganic– organic hybrid materials.