基于柔性环己烷六酸配体的两个碱土金属配位聚合物的水热合成及结构表征(英文)

Hydrothermal Syntheses and Crystal Structures of Two 3D Alkaline Earth Metal Coordination Polymers with Conformation-Flexible Cyclohexane-1,2,3,4,5,6-hexacarboxylate Ligand

水热反应条件下,碳酸锰和碳酸钡分别与水合环己烷六酸(H6LⅠ·H2O)(顺式椅式构型LⅠ:a,e,a,e,a,e)反应生成2个三维的配位聚合物[Mg3(LⅡ)(H2O)6](1)和[Ba2(H2LⅡ)(μ2-H2O)2](2)(反式椅式构型LⅡ:e,e,e,e,e,e),通过元素分析和红外光谱对这2个配位聚合物进行了表征。X射线单晶衍射分析表明配合物1属于三方晶系,R3空间群,晶胞参数为:a=1.4393(2)nm,c=1.4597(4)nm,β=120.00°,V=2.6187(10)nm3,Z=18;配合物2结构属于单斜晶系,C2/c空间群,晶胞参数为:a=1.6764(2)nm,b=0.9095(1)nm,c=1.0001(1)nm,β=105.991(2)°,V=1.4659(2)nm3,Z=4。配合物1是由反式椅式构型LⅡ配体桥连形成的高对称性的三维配位网络。在配合物2中,顺式的H6LⅠ配体也发生构型转变并脱去部分羧基质子形成H2LⅡ配体,将Ba离子连接成一个具有一维孔道的三维有孔框架结构。在这2个配合物中,环己烷六酸配体均采取反式椅式LⅡ构型,证明了碱土金属离子Mg髤及Ba髤在水热条件下通过配位作用可以稳定环己烷六酸配体的这种反式椅式构型。

Reactions of MgCO3/BaCO3 and 1,2,3,4,5,6-cyclohexanehexacarboxylic acid hydrate （H6LⅠ·H2O） （cis- chair conformation LⅠ： a,e,a,e,a,e） resulted in formation of two three-dimensional coordination polymers [Mg3（LⅡ） （H2O）6] （1） and [Ba2（H2LⅡ）（ μ2-H2O）2] （2） （trans-chair conformation LⅡ： e,e,e,e,e,e） under hydrothermal condition and were characterized by elemental analysis and IR. X-ray diffraction crystal structure analysis shows that 1 crystallizes in trigonal system , space group R3 with a=1.439 3（2） nm, c=1.459 7（4） nm, β=120.00°, V=2.618 7（10） nm3, Z=18; and 2 crystallizes in monoclinic system, space group C2/c with a=1.676 4（2） nm, b=0.909 5（1） nm, c=1.000 1（1） nm, β=105.991（2）°, V=1.465 9（2） nm3, Z=4. Complex 1 is a highly symmetrical network bridged by the trans-chair conformation L^Ⅱ ligand. In complex 2, the cis-chair H6L^Ⅰ ligand transformed to the partly deprotoned trans-chair H2L^Ⅱ ligand, which bridged the Ba atoms to generate a porous 3D framework with 1D channels, which are filled with the coordinated water molecules. In the two complexes, both of the flexible cyclohexanehexacarboxylate ligands adopt the trans-chair conformation L^Ⅱ, illustrating that the conformation L^Ⅱ can be stabilized by the coordination with alkaline earth Mg（Ⅱ）/Ba（Ⅱ） through hydrothermal syntheses.