点击次数：

论文类型：期刊论文

发表时间：2018-07-21

发表刊物：DALTON TRANSACTIONS

收录刊物：SCIE

卷号：47

期号：27

页面范围：9079-9089

ISSN号：1477-9226

摘要：Six novel organic-inorganic hybrid polyoxometalate derivatives, K[(H2O)(4)(3-Hpic)(2)Ce][(H2O)(5)(3-Hpic)(2)Ce] [PW10Ti2O40]center dot 11H(2)O 1, K[(H2O)(4)(3-Hpic)(2)Nd][(H2O)(5)(3-Hpic)(2)Nd][PW10Ti2O40]center dot 12H(2)O 2, K[(H2O)(4)(3-Hpic)(2)Sm][(H2O)(5)(3-Hpic)(2)Sm][PW10Ti2O40]center dot 8H(2)O 3,H[(H2O)(7)(4-Hpic)La][(4-Hpic)(2)LaPW11O39]center dot 14.5H(2)O 4, H[(H2O)(7)(4-Hpic)Ce][(4-Hpic)(2)CePW11O39]center dot 7.5H(2)O 5, and K(4-Hpic)(0.5)[(H2O)(6)(4-Hpic)Nd][(4-Hpic)(2) NdPW11O39]center dot 10H(2)O 6, (3-Hpic = 3-picolinic acid; 4-Hpic = 4-picolinic acid) have been synthesized and characterized by elemental analysis, IR, solid state UV-vis spectroscopy, thermal gravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Isostructural compounds 1-3 are hybrid dimers that consist of two Ti-substituted Keggin-type polyoxoanions [PW10Ti2O40](7-) and four Ln-3-Hpic coordination groups. The strong hydrogen bonds in 1-3 can make these dimers yield a 1D supramolecular chain. Compounds 4-6 are also dimers constructed from two lanthanide-substituted Keggin-type polyoxoanions [PW(11)LnO(39)](4-) and four 4-Hpic ligands, which are further linked by two Ln-4-Hpic groups to form a bi-supporting structure. Then these subunits are joined together by strong hydrogen-bonding interactions between polyoxoanions and coordinated water molecules to produce a 2D supramolecular framework. All these compounds as heterogeneous Lewis acid-base catalysts show high activity and high selectivity for the cyanosilylation of different carbonyl compounds under solvent-free conditions, and can be recycled without any obvious inactivation.