title: Keggin-Type Polyoxometalate-Based Metal-Organic Networks for Photocatalytic Dye Degradation.
abstract: The reaction of Keggin-type polyoxometalate (POM) units, transition-metal (TM) ions, and a rigid bis(imidazole) ligand (1,4-bis(1-imidazolyl)benzene (bimb)) in a hydrothermal environment led to the isolation of four new POM-based metal-organic networks, [H2 L][CuL][SiW12 O40 ]⋅2 H2 O (1), [H2 L]2 [Co(H2 O)3 L][SiW11 CoO39 ]⋅6 H2 O (2), KH[CuL]2 [SiW11 CoO39 (H2 O)]⋅2 H2 O (3), and [CuL]4 [GeW12 O40 ]⋅H2 O (4; L=bimb). All four compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Compounds 1 and 3 are new 3D networks with 1D channels. Compounds 2 and 4 contain 2D networks, which further stack into 3D supramolecular networks. The contributions of pH value, the negative charge of the POM, and the TM coordination modes to the construction of 3D networks were elucidated by comparing the synthetic conditions and structures of compounds 1-4. The photocatalytic properties of compounds 1-4 were investigated using methylene blue (MB) degradation under UV light. All compounds showed good catalytic activity and structural stability. The possible catalytic mechanism was discussed on the basis of active-species trapping experiments. The different photocatalytic activities of compounds 1-4 were explained by comparison of the band gaps of different POM species and different packing modes of POM units in these hybrid compounds.
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China.
authors.forename: Hong-Fang
authors.initials: HF
authors.lastname: Hao
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China.
authors.forename: Wen-Zhe
authors.initials: WZ
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China. zanghy100@nenu.edu.cn.
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Zang
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China.
authors.forename: Hua-Qiao
authors.initials: HQ
authors.lastname: Tan
authors.affiliation: School of Public Health, Jilin University, Changchun, Jilin, 130021, China. qiyanfei@jlu.edu.cn.
authors.forename: Yan-Fei
authors.initials: YF
authors.lastname: Qi
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China.
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, P.R. China. liyg658@nenu.edu.cn.
authors.forename: Yang-Guang
authors.initials: YG
authors.lastname: Li
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D007093:Imidazoles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008751:Methylene Blue / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D010782:Photolysis; D017973:Tungsten Compounds / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D001555:Benzene Derivatives; D007093:Imidazoles; D008670:Metals; D008751:Methylene Blue; D009942:Organometallic Compounds; D017973:Tungsten Compounds; C102296:polyoxometalate I; D000099294:Polyoxometalates
keywords: metal-organic frameworks; photocatalysis; polyoxometalates; rigid ligands