| Polyoxometalates?POMs?have potential applications in many fields such as analytical chemistry,materials science,catalysis,nanotechnology,chemical sensing,biochemistry,medicine and waste degradation.Many Keggin-type heteropolyanions have been synthetized,but polyoxometalate clusters with aluminium atom as heteroatom have been rarely used.Among the surface of[AlW12O40]5-anion possesses higher surface charge density and it's easier to be modified to form multifunctional composite material.Therefore,twelve novel Keggin type polyoxotungstoaluminates were obtained by hydrothermal synthesis in this paper.The chemical formulas of twelve compounds have been confirmed by elemental analysis and TG,which structures were characterized by IR,solid UV,XRD and single-crystal X-ray diffraction.The molecular formulas of the compounds:[Cu?en??bipy??H2O?]2[Al W12O40]·H3O·H2O?1?[Zn?bipy?3]3[{Zn?H2O??bipy?2}{Al W12O40}]2?2?[Ni?bipy?3]3[{Ni?H2O??bipy?2}{AlW12O40}]2?3?[Ag?bipy?2]8[{Ag?bipy?}{AlW12O40}]2?4?[Cd?bipy?3]2[AlW12O40]·H3O?5?[Fe?bipy?3]2[HAl W12O40]?6?[Cu?phen?2]2[HAl W12O40]?7?[Zn?phen?3]2[HAlW12O40]·4H2O?8?[Ag6?H2bim?5?Hbim?][AlW12O40]·4H2O?9?[Ag?bpy?][{Ag?bpy?}2(H2Al W12O40)]?H2O?10?[{Cu?bpy?}3(H2Al W12O40)]?H2O?11?[{Ag5?pz?7}{AlW12O40}]·4H2O?12??en=ethanediamine,bipy=2,2?-bipyridine,bpy=4,4?-bipyridine,phen=1,10-phenanthroline,H2bim=2,2'-bisimidazole,pz=pyrazine?The structures of the twelve compounds were characterized by X-ray single crystal diffraction:compounds 1-12 are complexes based on[AlW12O40]5-structural unit.Compound 1 is modified by en and 2,2'-bipy ligands.Each[AlW12O40]5-poly anion connects with the[Cu?en??bipy??H2O?]2+unit by supramolecular interaction to form 1D2D,3D structures.Compounds 2 and 3 are isomorphic,each[AlW12O40]5-cluster connects with[X?H2O??bipy?2]2+?X=Zn,Ni?fragments by terminal oxygen to form the[X?bipy?2?H2O?{Al W12O40}]3-?X=Zn,Ni?anion,further to form 1D structure through supramolecular interaction.The adjacent two“double chain”units are linked by[X?bpy?3]2+?X=Zn,Ni?fragments to form 2D layer and then form 3D network structure.In compound 4,[{Ag?bipy?}{AlW12O40}]4-fragments link[Ag?bipy?2]+by supramolecular interaction and hydrogen bonding interaction to exhibit 1D chain like butterfly and 2D structure like a coin lined up.Compounds 5-6 have similar structure:the supramolecular structure is composed of[AlW12O40]5-cluster anions and two[M?2,2?-bipy?3]2+?M=Fe,Cd?ions.Compounds 7-8 are modified by phen ligands,which the basic structural units are composed of a[AlW12O40]5-polyanion and a transition metal counterion.The adjacent structural units can form 2D and 3D structures by supramolecular interactions.In compound 9,six Ag ions and six bim ligands constitute a wave type of silver clusters,the polyoxoanion is wrapped by four silver clusters by supramolecular interaction and hydrogen bonding interaction to to form 2D and 3D structure.The compounds 10-11 have similar“three-chain belts”structure,but the coordination modes are different:[Al W12O40]5-of compound 10 coordinates with Ag+by two oxygen atoms in a symmetrical position,adjacent 1D chains and middle counter ion{Ag?bpy?}chain form 2D layer by?-?stacking interactions;[AlW12O40]5-units as tridentate ligand in compound 11,link Cu+with two adjacent terminal oxygens and one bridging oxygen atom respectively.The 2D layer is formed by supramolecular interaction.Compound 12 is the first 3D host-guest structure based on three-fold interpenetrated Ag-pz coordination polymer network.It is worth noting that“Y”-shaped Ag1-pz segment is suspended on the ring through sharing pz with Ag2-pz tetrahedron,which is important linkage unit extending 2D layers to three-fold interpenetrating Ag-pz network with?103·123??103??10?2?122·14?topology.The{AlW12}as inorganic‘guest'units are encapsulated into the channel of Ag-pz framework to form a complex POMOF3D network.The electrochemical properties and electrocatalytic properties for H2O2 of these compounds by cyclic voltammetry have been investigated.The results suggest that compounds 1-12 exhibit good electrochemical properties and catalytic properties.Using synthetic compounds as catalysts,we study on degradation for Rhodamine B?RhB?,methylene blue?MB?,methyl orange?MO?under UV irradiation.The results show that compounds 1-12 have good degradation effect on RhB,MB and MO.In addition,impedance experiments of synthetic compounds show that the proton conduction is in accordance with the Vehicle mechanism. |
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