Beijing National Laboratory for Molecular Sciences, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
Dalton Trans. 2009 Aug 7(29):5666-72. doi: 10.1039/b903613j. Epub 2009 Jun 8.
6-Hydroxypyridine-3-carboxylic acid (6-HOPy-3-CO(2)H) reacts with Ln(2)O(3) (Ln = Nd, Sm, Eu, Gd) and oxalic acid (H(2)OX) under hydrothermal conditions to generate four novel lanthanide-organic coordination polymeric networks [Ln(2)(1H-6-Opy-3-CO(2))(2)(OX)(2)(H(2)O)(3)] x 2.5 H(2)O (Ln = Nd, 1; Sm, 2; 1H-6-Opy-3-CO(2)(-) = 1-hydro-6-oxopyridine-3-carboxylate) and [Ln(1H-6-Opy-3-CO(2))(OX)(H(2)O)(2)] x H(2)O (Ln = Eu, 3; Gd, 4). The new co-ligand 1H-6-Opy-3-CO(2)(-) anion was generated by the autoisomerization of the single deprotonated 6-HOPy-3-CO(2)(-) anion (from the enol form into the ketone one). 1 and 2 are isomorphous, they possess a three-dimensional architecture constructed from Ln(3+) ions bridged by oxalate anions and two types of 1H-6-Opy-3-CO(2)(-) bridges, showing a three-nodal (4,5)-connected topology (3.4(2).5(2).6(3).7.8)(2)(3.5(3).6(2))(2)(3(2).6.7(2).8) or a simplified uninodal 6-connected topology (3(3).4(6).5(5).6), both topologies are completely new; while only one type of 1H-6-Opy-3-CO(2)(-) bridge is used to construct the two-dimensional layer networks of 3 and 4 besides oxalate bridges, both complexes 3 and 4 are isostructural, exhibiting the honeycomb topology 6(3). The lanthanide contraction effect is believed to play a key role in directing the formation of a particular structure. A magnetic study of 1-3 indicated that the coupling interaction between Ln(3+) ions is weak.
6-羟基吡啶-3-羧酸（6-HOPy-3-CO(2)H）与 Ln(2)O(3)（Ln = Nd、Sm、Eu、Gd）和草酸（H(2)OX）在水热条件下反应，生成四个新型镧系元素-有机配位聚合物网络[Ln(2)(1H-6-Opy-3-CO(2))(2)(OX)(2)(H(2)O)(3)] x 2.5 H(2)O（Ln = Nd，1；Sm，2；1H-6-Opy-3-CO(2)(-) = 1-羟基-6-氧代吡啶-3-羧酸根）和[Ln(1H-6-Opy-3-CO(2))(OX)(H(2)O)(2)] x H(2)O（Ln = Eu，3；Gd，4）。新的共配体 1H-6-Opy-3-CO(2)(-)阴离子是由单质子化 6-HOPy-3-CO(2)(-)阴离子的自动异构化（从烯醇形式到酮形式）生成的。1 和 2 是同构的，它们由草酸根阴离子和两种类型的 1H-6-Opy-3-CO(2)(-)桥连接的镧系元素离子构成三维结构，呈现三节点（4,5）连接拓扑结构（3.4(2).5(2).6(3).7.8)(2)(3.5(3).6(2))(2)(3(2).6.7(2).8)或简化的单节点 6 连接拓扑结构（3(3).4(6).5(5).6），两种拓扑结构都是全新的；而只有一种类型的 1H-6-Opy-3-CO(2)(-)桥被用于构建除草酸桥之外的 3 和 4 的二维层网络，复合物 3 和 4 是同构的，呈现蜂窝状拓扑结构 6(3)。镧系元素收缩效应被认为在指导特定结构的形成中起着关键作用。对 1-3 的磁性研究表明，镧系元素离子之间的耦合相互作用较弱。
