Reactions of lanthanide(III) nitrates with multi-donor carboxylate ligand in the presence of oxalate anion afforded four new lanthanide coordination polymers with three dimensional (3D) frameworks, namely, [Ln2(DPPA)2(μ2-C2O4)(H2O)2]·2H2O}n (Ln = Nd (1), Sm (2)) and [Ln2(HDPPA)2(DPPA)2]n (Ln = Tb (3), Yb (4)), (H3DPPA = 3-(4-hydroxyl pyridinium-1-yl) phthalic acid and H2C2O4 = oxalic acid). Compounds 1 and 2 are isostructural and isomorphous, featuring oxalate pillared binodal (4,5)-connected porous 3D framework with intersected 1D channels, in which the coordinated and lattice waters are accommodated. The complexes 3 and 4 are also isostructural, but featuring a (4,6)-connected 3D network based on a rectangular window composed of Ln(HDPPA)}+ extended anion chains, further interlinked by DPPA. The Tb(III) analogue exhibits intense characteristic green photoluminescence employing DPPA as an antenna. While Sm(III) compound 2 mainly involves ligand-to-ligand charge transfer. Variable-temperature susceptibility analyses of complexes 1 (Nd), 2 (Sm) and 3 (Tb) revealed that depopulation of the Stark levels together with weak antiferromagnetic interactions between the lanthanide ions lead to a continuous decrease in χMT when the samples are cooled from 300 to 2 K.
在
草酸盐阴离子存在下,
镧系元素(III)
硝酸盐与多供体
羧酸配体发生反应,产生了四种具有三维(3D)框架的新型
镧系元素配位聚合物、即[Ln2(
DPPA)2(μ2-
C2O4)(
H2O)2]-2 }n(Ln = Nd (1),Sm (2))和[Ln2(H
DPPA)2(
DPPA)2]n(Ln = Tb (3),Yb (4))(H3
DPPA = 3-(4-
羟基吡啶-1-基)
邻苯二甲酸,H2 =
草酸)。化合物 1 和 2 具有同构和同形结构,其特征是
草酸柱状双十二(4,5)连接多孔三维框架具有相交的一维通道,其中容纳了配位
水和晶格
水。复合物 3 和 4 也是同结构的,但其特征是基于由 Ln(H
DPPA)}+ 扩展阴离子链组成的矩形窗口的 (4,6)- 连接的三维网络,并通过
DPPA 进一步相互连接。利用
DPPA 作为天线,
锑(III)类似物显示出强烈的绿色光致发光特性。而 Sm(III)化合物 2 主要涉及
配体与
配体之间的电荷转移。对复合物 1(
钕)、2(
钐)和 3(
铽)的变温电感分析表明,当样品从 300 K 冷却到 2 K 时,斯塔克电平的去占位以及
镧系元素离子之间微弱的反
铁磁相互作用导致了 χ
MT 的持续下降。