Structure, adsorption and magnetic properties of chiral metal–organic frameworks bearing linear trinuclear secondary building blocks
作者:Zilu Chen、Xianlin Liu、Chuanbing Zhang、Zhong Zhang、Fupei Liang
DOI:10.1039/c0dt01278e
日期:——
The reactions of new chiral organic ligands trimesoyltri(L-alanine) (L-TMTAH3) or trimesoyltri(D-alanine) (D-TMTAH3) with transition metal salts in the presence of an ancillary ligand of 4,4â²-bipyridine gave two pairs of three dimensional frameworks [Co3(L-TMTA)2(4,4â²-bpy)4]·28H2O (1), [Co3(D-TMTA)2(4,4â²-bpy)4]·28H2O (2) [Ni3(L-TMTA)2(4,4â²-bpy)4]·2C2H5OH·14H2O (3) and [Ni3(D-TMTA)2(4,4â²-bpy)4]·2C2H5OH·14H2O (4). These compounds were characterized by elemental analysis, IR, and X-ray powder diffraction analysis and the structures of 1â3 were determined from X-ray single crystal diffraction analysis. Complexes 1â4 feature linear trinuclear secondary building blocks [M3(COO)4]2+ formed via the connection of three metal ions by four carboxylato groups from four TMTA3â ligands. Every adjacent two linear trinuclear secondary building blocks are linked by one and three 4,4â²-bipyridine molecules along the a and c axis, respectively, to form two-dimensional sheets, which are further connected by TMTA3â ligands to construct a porous three dimensional framework with one-dimensional channels. Compound 3 was taken as an example to investigate the adsorption properties of compounds 1â4. It revealed a saturated hydrogen uptake of 216.6 cm3 gâ1 (2.0wt%) at 11.1 atm measured at 77 K, a maximum CO2 uptake of 119.4 cm3 gâ1 (23.5wt%) at 19.5 atm measured at 298 K and a saturated CH4 uptake of 77.8 cm3 gâ1 (5.6wt%) at 27.1 atm measured at 298 K. The magnetic studies of complexes 1 and 3 indicate the presence of antiferromagnetic interactions between the metal ions in the two compounds.
新的手性有机配体三甲酰三(L-丙氨酸)(L-TMTAH3)或三甲酰三(D-丙氨酸)(D-TMTAH3)与过渡金属盐在辅助配体 4、4,4â²-联吡啶的辅助配体存在的情况下,过渡金属盐与三甲基三(D-丙氨酸)(D-TMTAH3)产生了两对三维框架[Co3(L-TMTA)2(4,4â²-bpy)4]Â-28H2O(1)、[Co3(D-TMTA)2(4、4â²-bpy)4]Â-28H2O (2)、[Ni3(L-TMTA)2(4,4â²-bpy)4]Â-2C2H5OHÂ-14H2O (3)和[Ni3(D-TMTA)2(4,4â²-bpy)4]Â-2C2H5OHÂ-14H2O (4)。通过元素分析、红外光谱和 X 射线粉末衍射分析对这些化合物进行了表征,并通过 X 射线单晶衍射分析确定了 1â3 的结构。配合物 1â4 具有线性三核二级结构单元 [M3(COO)4]2+,由四个 TMTA3â 配体的四个羧基连接三个金属离子而形成。每相邻两个线性三核二级结构单元分别由一个和三个 4,4â²-联吡啶分子沿 a 轴和 c 轴连接,形成二维薄片,再由 TMTA3â 配体进一步连接,构建出具有一维通道的多孔三维框架。以化合物 3 为例,研究了化合物 1â4 的吸附特性。在 77 K 温度下,11.1 atm 的饱和氢气吸附量为 216.6 cm3 gâ1 (2.0wt%);在 298 K 温度下,19.5 atm 的最大二氧化碳吸附量为 119.4 cm3 gâ1 (23.5wt%);饱和甲烷吸附量为 77.对复合物 1 和 3 的磁性研究表明,这两种化合物中的金属离子之间存在反铁磁相互作用。