Construction and isomeric transformation of polyoxometalates directed by 1,[small omega]-bis(pyridinium)alkane templates

• Published in: CrystEngComm 2011-01, Vol.13 (16), p.5071-5081
• Main Authors: Niu, Yun-Yin, Wang, Ling-Fang, Lv, Xiao-Rui, Du, Hai-Juan, Qiao, Yong-Zhen, Wang, Hong-Mei, Song, Li-Sha, Wu, Ben-Lai, Hou, Hong-Wei, Ng, Seik Weng
• Format: Article
• Language: English
• Subjects: Acetaldehyde; Anions; Catalytic activity; Cations; Isomers; Polyacids; Self assembly; Transformations
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/C1CE05245D

Ten novel inorganic-organic hybrid polyoxometalates, namely, [1,3-bis(pyridinium) propane]2[[small alpha]-Mo8O26] (1), [1,4-bis(pyridinium)butane]2[1D-Mo8O26] (2), [1,5-bis(pyridinium)pentane]2[[small theta]-Mo8O26] (3), [1,6-bis(pyridinium)hexane]2[1D-Mo8O26] (4), [1,7-bis(pyridinium)heptane]2[[small beta]-Mo8O26] (5), [1,8-bis(pyridinium)octane]2[[small theta]-Mo8O26] (6), [1,9-bis(pyridinium)nonane]2[([small alpha] + [small beta])-Mo8O26] (7), [1,10-bis(pyridinium)decane]2[[small beta]-Mo8O26] (8), [1,11-bis(pyridinium)undecane]2[[small beta]-Mo8O26] (9), [1,12-bis(pyridinium)dodecane]2[[gamma]-Mo8O26] (10), (Scheme 1) were synthesized by cation templated self-assembly with octamolybdate anions under hydrothermal reaction conditions. Crystal data analysis revealed that these compounds were all composed of discrete organic cations and polyacid anions [Mo8O26]4- interacting by electrostatic and hydrogen bond interactions. Interestingly in these compounds the anion fraction could take on [small alpha]-, [small beta]-, [small theta]-, [gamma]-[Mo8O26]4- 0D isomers or rare 1D- polymeric frameworks with a simple length modification of the alkane components. Moreover, these polyacid compounds had definite catalytic activities on the oxidation reaction of acetaldehyde to acetic acid and the relationship of structure/catalytic activities were initially demonstrated.