| Our work is focused on the design and preparation of multi-functionality hybrids based on the polyoxometalates and meal-organic framework (POMs/MOFs). This work includes as follows: systematic research into the synthesis, structure, stability, porosity and acidity of the POMs/MOFs hybrids. We emphatically develop the catalytic activity of these compounds as solid acid catalysts; expand the designing ideas in POM-supported catalysts; establish the catalytic mode of MOF/POM supported catalysts; expend this approach to other transformations with suitable MOFs; explore the relation and effect between the MOF and the immobilized POMs including the size, structure and symmetry, which can direct the design and synthesis of new metal-organic frameworks for encapsulating the POM; investigate other functionality of these materials.Under hydrothermal conditions, we select benzentricaboxylate (BTC) as organic to react with different Keggin polyoxometalates (POMs) and fourteen new POMs/MOFs hybrids were successful synthesized. These new compounds were characterized by elemental analysis, FT-IR, XPS, TGA, XRD, UV-vis spectra, N2 adsorption studies, and X-ray crystallographic analyses. According to their functionalities, they can be separated into three groups:1. A series of remarkable crystalline compounds were constructed from the different Keggin polyoxometalates and a charge-neutral host metal-organic framework under simple one-step hydrothermal reaction, which are denoted as NENU-K (n=l-6):[Cu2(BTC)4/3(H2O)2]6[H2SiW12O40]·(C4H12N)2·30H2O (1) [Cu2(BTC)4/3(H2O)2]6[H2GeW12O40]·(C4H12N)2·30H2O (2) [Cu2(BTC)4/3(H2O)2]6[HPW12O40]·(C4H12N)2·25H2O (3) [Cu2(BTC)4/3(H2O)2]6[H2SiMo12O40]·(C4H12N)2·30H2O (4) [Cu2(BTC)4/3(H2O)2]6[HPMo12O40]·(C4H12N)2·20H2O (5) [Cu2(BTC)4/3(H2O)2]6[HAsMo12O40]·(C4H12N)2·20H2O (6)In these compounds the Keggin polyanions were alternately arrayed, as noncoordinating guests, in the cuboctahedral cages of Cu-BTC-based (BTC= benzentricab oxy late) metal-organic framework host matrix that is isostructural with the famous compound HKUST-1. In the framework, the paddle-wheel Cu2-clusters are connected through the BTC ligands into a three-dimensional (3, 4)-connected cubic network with two kinds of pores (A and B), polyanions serve as guests and fill in the pore A. The representative acid catalytic performance of compound 3 containing PW12 species was assessed by the hydrolysis of esters in excess water, showing high catalytic activity, and it can be used repeatedly without loss of activity. Moreover, a catalytic selectivity depended on the molecular size of substrates and the accessibility of substrates for the surface exposed pore was observed. It is the first time that the well-defined crystalline MOF-supported POM compound behaves as true heterogeneous acid catalyst.2.A series of hybrids constructed from Keggin polyoxoanions and Sodalite-Type metal-organic framework with entatic metal centers, which are denoted as NENU-K (n=21-27):H3[(Cu4Cl)3(BTC)8]2[PW12O40]-(C4H12N)6(21)H3[(Cu4Cl)3(BTC)8]2[PMo12O40]-(C4H12N)6(22)H4[(Cu4Cl)3(BTC)8]2[SiW12O40]-(C4H12N)6(23)H4[(Cu4Cl)3(BTC)8]2[SiMo12O40]-(C4H12N)6(24)H3[(CU4Cl)3(BTC)8]2[ASW12O40]-(C4H12N)6(25)H3[(Cu4Cl)3(BTC)8]2[AsMo12O40]-(C4H12N)6(26)H5[(Cu4Cl)3(BTC)8]2[FeIIIW12O40]-(C4H12N)6(27)These compounds were constructed from Keggin-type polyoxometalates and metal-organic framework containing Cu4-μ4-Cl-carboxylic SBUs, in which the polyanions with 35 negative charge are introduced into an anionic Sodalite-type MOF with entatic metal centers. The Sodalite-type metal-organic framework comprised of simple and basic benzentricaboxylate ligand is unprecedented. On the other hand, the polyanions are introduced into an anionic MOF for the first time herein. In addition, the host framework with entatic metal centers is very rare, and they exhibit remarkable affinity to some substrates. Indeed, this work offers a new perspective in the design of functional materials. Such compounds may have a brilliant development in the catalytic or storage materials with "value-adding properties".3.A new crystalline polyoxometalate (POM)/metal-organic framework (MOF) hybrid [Cu2(BTC)4/3(H2O)2]6[H5PTi2W10O40]-(C4H12N)2-20H2O (10) was obtained from the one-step hydrothermal reaction of copper nitrate, benzentricaboxylate (BTC), and dititanium-substituted polyoxotungstate. In this compound, the Keggin-type [PTi2W10O40]7- anion that is famous for its antiviral and antitumoral activities, was alternately arrayed as non-coordinating guest in the cuboctahedral cage of a Cu-BTC-based neutral metal-organic framework. The slow and complete delivery of [PTi2W10O40]7- was achieved in water at room temperature after 1 week, which was evaluated using UV-vis spectrum, IR spectroscopy, XRD pattern, elemental analyses, and N2 sorption measurements. The delivery also was effective under physiological conditions (SBF), which indicated that a new property of POMs/MOFs hybrids has been developed, namely, the crystalline MOF act as a convenient delivery system for POM drug.
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