Abdelbaky Mohammed S M, Amghouz Zakariae, García-Granda Santiago, García José R
Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo-CINN, 33006 Oviedo, Spain.
Servicios Científico-Técnicos, Universidad de Oviedo-CINN, 33006 Oviedo, Spain.
Polymers (Basel). 2016 Mar 16;8(3):86. doi: 10.3390/polym8030086.
Metal-organic frameworks assembled from Ln(III), Li(I) and rigid dicarboxylate ligand, formulated as [LiLn(BDC)₂(H₂O)·2(H₂O)] (MS1-6,7a) and [LiTb(BDC)₂] (MS7b) (Ln = Tb, Dy, Ho, Er, Yb, YEu, YTb, and H₂BDC = terephthalic acid), were obtained under hydrothermal conditions. The isostructural MS1-6 crystallize in monoclinic 2₁/c space group. While, in the case of Tb a mixture of at least two phases was obtained, the former one (MS7a) and a new monoclinic 2/c phase (MS7b). All compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TGA), vibrational spectroscopy (FTIR), and scanning electron microscopy (SEM-EDX). The structures of MS1-6 and MS7a are built up of inorganic-organic hybrid chains. These chains constructed from unusual four-membered rings, are formed by edge- and vertex-shared {LnO₈} and {LiO₄} polyhedra through oxygen atoms O3 (vertex) and O6-O7 (edge). Each chain is cross-linked to six neighboring chains through six terephthalate bridges. While, the structure of MS7b is constructed from double inorganic chains, and each chain is, in turn, related symmetrically to the adjacent one through the glide plane. These chains are formed by infinitely alternating {LiO₄} and {TbO₈} polyhedra through (O2-O3) edges to create Tb⁻O⁻Li connectivity along the -axis. Both MS1-6,7a and MS7b structures possess a 3D framework with 1D trigonal channels running along the and axes, containing water molecules and anhydrous, respectively. Topological studies revealed that MS1-6 and MS7a have a new 2-nodal 3,10-c net, while MS7b generates a 3D net with unusual β-Sn topology. The photoluminescence properties Eu- and Tb-doped compounds (MS5-6) are also investigated, exhibiting strong red and green light emissions, respectively, which are attributed to the efficient energy transfer process from the BDC ligand to Eu and Tb.
由镧系元素（III）、锂（I）和刚性二羧酸配体组装而成的金属有机框架，化学式为[LiLn(BDC)₂(H₂O)·2(H₂O)]（MS1 - 6,7a）和[LiTb(BDC)₂]（MS7b）（Ln = Tb、Dy、Ho、Er、Yb、YEu、YTb，H₂BDC = 对苯二甲酸），是在水热条件下获得的。同构的MS1 - 6以单斜2₁/c空间群结晶。而对于Tb，得到了至少两种相的混合物，前者（MS7a）和一种新的单斜2/c相（MS7b）。所有化合物均通过单晶和粉末X射线衍射、热分析（TGA）、振动光谱（FTIR）以及扫描电子显微镜（SEM - EDX）进行了研究。MS1 - 6和MS7a的结构由无机 - 有机杂化链构成。这些由不寻常的四元环构成的链，是通过氧原子O3（顶点）和O6 - O7（边）由边共享和顶点共享的{LnO₈}和{LiO₄}多面体形成的。每条链通过六个对苯二甲酸桥与六个相邻链交联。而MS7b的结构由双无机链构成，并且每条链又通过滑移面与相邻链对称相关。这些链由{LiO₄}和{TbO₈}多面体通过（O2 - O3）边无限交替形成，以沿z轴创建Tb - O - Li连接。MS1 - 6,7a和MS7b的结构都具有一个三维框架，沿x和y轴有一维三角通道，分别包含水分子和无水物。拓扑研究表明，MS1 - 6和MS7a具有一种新的2 - 节点3,10 - c网络，而MS7b生成一种具有不寻常β - Sn拓扑的三维网络。还研究了铕和铽掺杂化合物（MS5 - 6）的光致发光性质，分别表现出强烈的红光和绿光发射，这归因于从BDC配体到铕和铽的高效能量转移过程。
