Abstract Three new Pb(II) coordination polymers, namely [Pb2(mand)2]n (1), {[Pb(L-Hmand)(NO3)(5,5′-DM-2,2′-bipy)]·2H2O}n (2-L), {[Pb(D-Hmand)(NO3)(5,5′-DM-2,2′-bipy)]·2H2O}n (2-D) (H2mand = D/L-mandelic acid, 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridyl), have been prepared. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, powder X-ray diffraction and thermogravimetric analyses. Complex 1 crystallizes in the triclinic system with space group P-1, and displays a 2D layer structure. Complexes 2-L and 2-D are pairs of enantiomers. They crystallize in the same chiral space group P212121 and feature a 1D chain structure. The influence of the temperature and steric-hinerance of 5,5′-dimethyl-2,2′-dipyridyl molecules on constructing enantiomeric Pb(II) coordination polymers based on chiral mandelic acid ligands have been demonstrated. In addition, the circular dichroism (CD) spectroscopy of 2-L and 2-D exhibit obvious positive or negative Cotton effects indicating their homochirality. The luminescent properties of 1, 2-L and 2-D in the solid state have also been investigated.

中文翻译：

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D/L-扁桃酸基三种新型Pb(II)配位聚合物：温度和5,5'-二甲基-2,2'-二吡啶基辅助配体对构建对映体配位聚合物的影响

摘要 三种新型 Pb(II) 配位聚合物，即 [Pb2(mand)2]n (1)、{[Pb(L-Hmand)(NO3)(5,5'-DM-2,2'-bipy)] ·2H2O}n (2-L), {[Pb(D-Hmand)(NO3)(5,5'-DM-2,2'-bipy)]·2H2O}n (2-D) (H2mand = D /L-扁桃酸，5,5'-DM-2,2'-bipy = 5,5'-二甲基-2,2'-联吡啶），已制备。它们的结构已通过单晶 X 射线衍射分析确定，并通过元素分析、粉末 X 射线衍射和热重分析进一步表征。配合物 1 在空间群 P-1 的三斜晶系​​中结晶，并显示出二维层状结构。配合物 2-L 和 2-D 是对映异构体对。它们在相同的手性空间群 P212121 中结晶，并具有一维链结构。5,5'-二甲基-2的温度和空间位阻的影响，已经证明了基于手性扁桃酸配体构建对映体 Pb(II) 配位聚合物的 2'-联吡啶分子。此外，2-L 和 2-D 的圆二色性 (CD) 光谱表现出明显的正或负 Cotton 效应，表明它们的同手性。还研究了固态中 1、2-L 和 2-D 的发光特性。