| Polyoxometalates?POMs?,as a discrete nanometric metal oxygen clusters with strong coordination abilities and excellent properties in the fields of catalysis biology,magnetism and material science,have been widely used to construct metal–organic frameworks?MOFs?.In this paper,we ultimately selected BW12 and P2W18 as inorganic building blocks or templates,common nitrogen-containing organic ligands as an organic building block to obtain four POM-based MOFs with charming structures and ‘value-adding' properties by adjusting the reaction conditions and the ratio of raw materials under hydrothermal conditions.The compounds were characterized by single crystal X-ray diffractions,TG,XRD and IR.Furthermore,the electrochemical and photocatalytic properties of 1-3 were studied.1.Under hydrothermal conditions,we used BW12 as the building unit,transition metal?Co,Ni,Cu?and organic ligands to synthesize three POM-based MOFs:[H2bimb]1.5[Co?bimb?1.5?H2O?(BW12O40)] ·4H2O?1?,[H2bimb]1.5[Ni?bimb?1.5?H2O?(BW12O40)] ·4H2O?2?,K[H2bimb][Cu?bimb?(BW12O40)] ·2H2O?3?bimb=1,4-bis?1-imidazoly?benzeneThe compounds 1 and 2 are isomorphic,and transition metal ions Co2+ or Ni2+ are connected with BW12 and bimb to display a two-dimensional layered structure.In compound 3,BW12 anions are connected by K+ and Cu2+ to form a two-dimensional planar structure,and further form a three-dimensional framework through the connection of bimb.2.Under hydrothermal conditions,we used P2W18 as a template,Ni2+ and organic ligands to synthesize a POM-based MOFs:H2[Ni?bimb?2?bimbp?0.5?H2O?2][P2W18O62]0.5·3H2O?4?bimb = 1,4-bis?1-imidazoly?benzene;bimbp = 4,4'-bis?imidazolyl?biphenylIn compound 4,a one-dimensional chain structure is formed by Ni2+,bimb ligands and bimbp ligands with P2W18 as template.On the basis of the structure,the chains are stacked to form a three-dimensional network structure.Notely,we were surprised to find that the bimb ligands in-situ transformed to bimbp ligands,which has not been reported before. |
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