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论文类型：期刊论文
发表时间：2015-01-01
发表刊物：CRYSTENGCOMM
收录刊物：SCIE、Scopus
卷号：17
期号：7
页面范围：1531-1540
ISSN号：1466-8033
摘要：By controlling the reaction temperatures, four new architectures based on EvansShowell type polyoxometalate, [Ln(H2O)(5)][Ln(H2O)(7)][Co2Mo10H4O38] 6H(2)O (Ln = Sm 1; Eu 2), and (NH4)(3)[Ln(H2O)(6)][Co2Mo10H4O38] 6H(2)O (Ln = Sm 3; Eu 4) have been synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, solid diffuse reflective spectrum, powder X-ray diffraction and single crystal X-ray diffraction. Compounds 1 and 2 are racemic compounds, obtained at the higher temperature (85 degrees C). They show a 1D ladderlike structure constructed from left-handed chain and right-handed chain linked by lanthanide cations, which represent the first 1D self assembly based on EvansShowell type polyoxometalate. When the reaction temperature was decreased to room temperature (25 degrees C), two chiral species 3 and 4 were obtained, showing a mono-supporting structure composed of one [Co2Mo10H4O38](6-) polyoxoanion and one [Ln(H2O)(6)](3+) unit. They crystallize in the chiral space group P2(1), as conglomerates of two enantiomerically pure crystals. Their absolute configuration were determined by the Flack parameters and solid state circular dichroism spectroscopy. The structural differences between 1(2) and 3(4) reveal that the reaction temperature is the key factor controlling the products from racemic compounds to conglomerates. Four compounds 14 acted as Lewis acidbase catalysts through a heterogeneous manner to catalyse cyanosilylation with excellent efficiency