Synthesis And Characterization Of Novel Keplerate TypeMo-O Based Nano Polyoxometalates

In this paper, three types of derivatives of the inorganic Keplarate type Mo-O based polyoxometalates (denoted{Mo132}) were investigated by reacting the{Mo132} with the specified reactants such as nicotinic acid, isonicotinic acid, Ln3+(Ln= Pr, Tb) and M2+(M= Co, Ni) under different conditions at room temperature. The main achievements and creative aspects are given below.(1) Polyoxometalates now have a history of 100 years, the design and synthesis of new polyoxometalate-based compounds with novel structures and properties has been the basis for the development of polyoxometalates chemistry. While the research on the traditional Keggin-, Dawson-and other types polyoxometalates is proceeding more and more deeper, the research on supramolecular chemistry of organic-inorganic hybrids based on the Keplerate type polyoxometalates has just started. Inspired by the high potentials in catalytic, magnetic, and optical fields of organic-inorganic hybrids based on the Keplerate type polyoxometalates, we synthesized two new derivatives and characterized them by single-crystal x-ray diffraction IR NMR and other methods.(2)Reaction of an aqueous solution of Tb3+ with the highly charged nano-capsule of the Keplerate type{(Mo)Mo5O21(H2O)6}12{Mo2O4(SO4)}30 having 20 nanosized pores and channels allows investigating influence of external proton concentration on the entrance of cations like Tb3+ in the nano-capsule as an artificial cell model; the number of cations that can enter the capsule decreases with decreasing pH of the reaction solution, a phenomenon resembling the proton regulation of ion channels in biological cells, is characterized by x-ray single-crystal structure analysis, IR, UV-vis spectroscopic techniques.(3) Two new compounds by interacting the Mo-O based polyoxometalates(POM) of Keplerate type with two solution both containing two different types of cations were isolated and characterized. Analysis on their single crystal structures reveals that these two different types of cations in each compound are well separated by the nano capsule and are located in the capsule at different position. What worthy to be pointed out is that two kinds of metal ions are separated at the same time by the same nano-capsule can be recognized as a novel type of ionic nano size exclusion chromatography behavior. The single-crystal X-ray diffraction analyses also shows that the big Tb and Pr cations pass through the channel into the inside of the capsule, while the small Co and Ni cations still remains outside the capsule in their hydration complex forms, a phenomena resembling the ionic channel in biological system.