Design,synthesis And Properties Of Novel Polyoxovanadates–based Metal–organic Polyhedra

Metal-organic polyhedra are discrete molecular structures formed by metal atoms or metal clusters as vertices and carboxylates or pyridine/pyrimidine organic ligands as sides or faces.In this paper,seven novel Polyoxovanadates-based metal-organic polyhedra were successfully designed and synthesized by selecting Polyoxovanadates-based secondary building units(SBUs)with different numbers of nuclei ligated with different dentate,tridentate ligands.They were analyzed by single crystal X-ray diffraction,powder X-ray diffraction(PXRD),infrared,and thermogravimetric analyses.In addition,the iodine adsorption and dye adsorption properties of some of the structures were also explored and compared.1.An Anderson-like alkoxypolyoxovanadate cluster[V6O6(OCH3)9X]2-(X=SO4 or C6H5PO3)was used as a triple linkage vertex and the rigid linear carboxylic acid ligand 2,6naphthalenedioic acid(2,6-H2NDC)was designed and synthesized as an organic ligand for two examples of metal-organic polyhedra.The difference between the two structures is the modification of the interior of the molecular cage by the introduction of phenylphosphonic acid in compound 2.The introduction of phenylphosphonic acid reduced the space inside the molecular cage from 1100 ?3 to 700 ?3.Interestingly,the iodine adsorption performance of compound 2 was improved by more than 3 times compared to 1 after the introduction of phenylphosphonic acid.These findings can provide insight into the modification and functionalization within the cage of MOPs.[NH2Me2]8{[V6O6(OCH3)9(SO4)]4(2,6-NDC)6}(MeOH)15(DMA)9(1)[NH2Me2]8{[V6O6(OCH3)9(C6H5PO3)]4(2,6-NDC)6}(MeOH)9(DMA)10(2)2,6-NDC=2,6-naphthalenedioic acid2.Based on the above work,an attempt was continued to explore the effect of functionalized SBUs on the crystal structure.Novel metal-organic polyhedra were constructed using {V6P} as the apex,the tetradentate ligand homophthalic tetracarboxylic acid and the dentate long-chain ligand 4,4’-stilbenedicarboxylic acid as organic ligands.When {V6P} is ligated with the former,it can bridge with two of the counterpart carboxylic acids to form compound 3 in a tetrahedral configuration,while when attached to the latter,it is able to form a novel structure with an internally entangled entanglement and a twisted octahedral topology 4.Based on their basic characterization,the iodine adsorption properties of compound 3 and the solid-state photoluminescence properties of compound 4 were explored.[NH2Me2]8[V6O6(OCH3)9(C6H5PO3)]4(L1)6(3)[NH2Me2]12[V6O6(OCH3)9(C6H5PO3)]6(L2)9(4)L1=homotetracarboxylic acidL2=4,4’-stilbenedicarboxylic acid3.Two isomorphic truncated tetragonal compounds 5 and 6 were obtained by choosing the tetra-connected {V5Cl} as the apex and linking it to the angular dentate ligands 3,5pyridinedicarboxylic acid and 3,5-dicarboxybenzenesulfonic acid;compound 7 of octahedral and tetra-prismatic co-crystallization was obtained by using homobenzotriacetic acid and angular dentate ligand 3,5-dicarboxyphenol as the mixed ligand.Compounds 6 and 7 have similar iodine adsorption properties;also compound 6 has good ability to adsorb cationic dyes and can selectively adsorb cationic dyes in the dye mixture.[NH2Me2]8[V5O9Cl]4(L3)8(5)[NH2Me2]8[V5O9Cl]4(L4)8(6)[NH2Me2]8[V5O9Cl]4(L5)8+[NH2Me2]12[V5O9Cl]6(BTC)12(7)L3=3,5-pyridinedicarboxylic acidL4=3,5-dicarboxybenzenesulfonic acidL5=3,5-dicarboxyphenolBTC=homobenzotriacetic acid...