两种吡啶多羧酸与稀土Eu（III）配合物的结构与光致发光性质

用高氯酸铕和3,5-吡啶二甲酸、2,4,6-吡啶三甲酸在水热条件下反应合成了一个含有两种吡啶多羧酸阴离子配体的三维配位聚合物{Eu2(2,4,6-Hptc)(3,5-pdc)2(H2O)8]·6H2O}n(1)(2,4,6-H3ptc =2,4,6-吡啶三甲酸；3,5-H2 pdc =3,5-吡啶二甲酸)。单晶X-射线衍射分析表明,该配合物属单斜晶系,C2/c空间群,晶胞参数为a=2.0106(11) nm,b=1.1048(6) nm,c=1.7591(10) nm,β=112.117(8)°,α=γ=90°。配合物的中心Eu3+与九个氧原子配位,其中五个氧原子来自配体羧基氧原子,四个来自配位水分子,这些氧原子形成了变形三帽三棱柱结构。3,5-pdc阴离子的两个羧酸根分别以螯合方式连接两个Eu3+,形成一维链状结构。2,4,6-Hptc以铵盐形式用2-和6-位羧基配位,4-位羧基没有与金属离子配位,通过2,4,6-Hptc的配位将由3,5-pdc与Eu3+形成的一维链连接成一维梯状链结构。该配合物在紫外光的激发下显示红色荧光,具有良好的光致发光性质。

Structure and Photoluminescence Properties of a Eu(III) Complex with Two Ligands of Mixed Pyridinecarboxylic Acid

A 3D europium coordination polymer {Eu2(2,4,6-Hptc)( 3,5-pdc)2(H2O)8]·6H2O}n(1) (2, 4, 6-H3 ptc = 2, 4, 6-pyridinetricarboxylic acid;3, 5-H2 pdc = 3, 5-pyridinedicarboxylic acid ) was synthesized by hydrothermal method using europium perchlorate reacting with 3,5-pyridinedicarboxylic acid and 2,4,6-pyridinetricarboxylic acid. X-ray diffraction analysis of single crystal shows that the complex is crystallized in monoclinic system, C2/c space group. The cell parameters are as follows a=2. 0106(11) nm,b=1. 1048(6) nm,c=1. 7591(10) nm,β = 112. 117(8) °,α = γ = 90°. Eu3+ ions in the complex is coordinated with nine oxygen atoms. Five O atmos are from the carboxylate of lignds and the other four O atoms are from coordination water molecules. They are formed a distorted tricapped trigonal prism. The two carboxylates of each 3,5-pdc anion coordinates with Eu3+ by chelating way and a 1D chain structure is formed. 2,4,6-Hptc anions coordinate with Eu3+ by the 2-and 4-carboxylates. The 4-carboxylate does not coordinate. The 1D chain structres formed with 3,5-pdc anions and Eu3+ are further connected by 2,4,6-Hptc anions and 1D ladder shaped structure are constructed. The complex exhibits intense characteristic luminescence of Eu3+ with excitation of UV-rays.