点击次数：
论文类型：期刊论文
发表时间：2012-07-21
发表刊物：DALTON TRANSACTIONS
收录刊物：SCIE、EI、PubMed、Scopus
卷号：41
期号：27
页面范围：8390-8400
ISSN号：1477-9226
摘要：Six 3D architectures based on lanthanide-substituted polyoxometalosilicates, KLn[(H2O)(6)Ln](2)[(H2O)(4)-LnSiW(11)O(39)](2)center dot nH(2)O (Ln = La 1, n = 42; Ce 2, n = 40), H[(H2O)(6)Nd](2)[(H2O)(7)Nd][(H2O)(4)NdSiW11O39]-[(H2O)(3)NdSiW11O39]center dot 13H(2)O (3), H2K2[(Hpic)(H2O)(5)Ln](2)[(H2O)(4)LnSiW(11)O(39)](2)center dot nH(2)O (Ln = La 4, n = 18.5; Ce 5, n = 35; Nd 6, n = 36; Hpic = 4-picolinic acid), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, TG analysis, powder X-ray diffraction and single crystal X-ray diffraction. Compounds 1 and 2 are isostructural, built up of lanthanide-substituted polyoxoanions [{(H2O)(4)Ln(SiW11O39)}(2)](10-) linked by Ln(3+) cations to form a 3D open framework with 1D channels. The polyoxoanion [{(H2O)(4)Ln(SiW11O39)}(2)](10-) consists of two alpha(1)-type mono-Ln-substituted Keggin anions. When Nd3+ ion was used instead of La3+ or Ce3+ ions, compound 3 with a different structure was obtained, containing two kinds of polyoxoanions [{(H2O)(4)Nd(SiW11O39)}(2)](10-) and [{(H2O)(3)Nd(SiW11O39)}(2)](10-) which are connected together by Nd3+ ions to yield a 3D framework. When 4-picolinic acid was added to the reaction system of 1-3, isostructural compounds 4-6 were obtained, constructed from the polyoxoanions [{(H2O)(4)Ln(SiW11O39)}(2)](10-) linked by picolinate-chelated lanthanide centers to form a 3D channel framework. From a topological viewpoint, the 3D nets of 1, 2, 4, 5 and 6 exhibit a (3,6)-connected rutile topology, whereas the 3D structure of 3 possesses a rare (3,3,6,10)-connected topology. The magnetic properties of 2, 3, 5 and 6 have been studied by measuring their magnetic susceptibilities in the temperature range 2-300 K.