Structural Investigation of Flexible 1,4-Bis(1,2,4-triazol-1-ylmethyl)benzene Ligand in Keggin-Based Polyoxometalate Frameworks

摘要

By introducing the flexible 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) ligand into the molybdate system under the hydrothermal conditions, seven novel Keggin-based frameworks were obtained: [Ag(btx)](4)[SiMo12O40]center dot 2H(2)O (1), [Cu(btx)(4)-[SiMo12O40] (2), [Cu(btx)(2)](2)[SiMo12O40] (3), [Zn(btx)(2)](2)[SiMo12O40]center dot 0.5H(2)O (4) and [M-2(H2O)(4)(btx)(3)][SiMo12O40]center dot 4H(2)O (M = Mn, Ni and Co) (5-7). Compound 1 contains 0D (zero dimensional) Keggin-based fragment, ID polymer chain and 0D+1D polypseudo-rotaxane motif. Compound 2 exhibits interesting 1D+2D poly-pseudo-rotaxane architecture. Compound 3 has a 3D 4-connected diamond-related polymeric framework, which entraps the Keggin polyoxoanion into the stellate channels. Compound 4 contains isolated Keggin polyoxoanions and zipperlike polymer fragments, which are constructed from pairs of crumpled nets. Isostructural compounds 5-7 exhibit 2D -> 2D interpenetrated network structure featuring both polyrotaxane and polycatenane characters.