一维链状4-乙基苯甲酸镧配合物[La(EBA)_3(EBAH)(H_2O)]_n的合成、晶体结构和性质研究(英文)

水热法合成了配位聚合物La(EBA)3(EBAH)(H2O)]n(EBA=4-乙基苯甲酸根,EBAH=4-乙基苯甲酸),并通过X-射线衍射单晶结构分析、红外光谱、紫外光谱、荧光光谱以及热重分析对配合物进行了结构和性质研究。配合物属三斜晶系,P1空间群。该配合物具有一维链状结构。La3+离子与9个O原子配位,其中4个O原子来自4个双齿桥联的4-乙基苯甲酸根,3个O原子来自2个螯合-桥联的4-乙基苯甲酸根,1个O原子来自1个中性的4-乙基苯甲酸,1个O原子来自配位水分子。La3+离子处于九配位扭变的三帽三角棱柱构型中。相邻La3+离子通过双齿桥联或螯合桥联的4-乙基苯甲酸根联结成一维链状结构。存在于分子内的氢键使一维链状结构更加稳定。由于相邻一维链的苯环间存在弱的π…π堆积作用,使分子沿着a轴堆积形成二维层状结构。同时,标题配合物固体具有光致发光特性,蓝光区的较强发射归于配体的π→π*电子跃迁。

Synthesis, Crystal Structure and Properties Study of 1D Chain-Like Lanthanum 4-ethylbenzoate Complex [La(EBA)3(EBAH)(H2O)]n

The coordination polymerLa(EBA)3(EBAH)(H2O)]n(EBA=4-ethylbenzoate,EBAH=4-ethylbenzoic acid) was synthesized by hydrothermal method in the presence of melamine and characterized by X-ray single crystal structural analysis,IR spectrum,UV spectrum,fluorescence spectrum,and thermogravimetric analysis.The complex crystallizes in triclinie crystal system and P1 space group with the cell dimensions:01=0.953 19(3) nm,b=1.403 78(5) nm,c=1.498 47(5) nm,α=65.024(2)°,β=74.942(2)°,γ=74.734(2)°.The complex has 1D chain-like structure.La3+ ion is nine-coordinated by four oxygen atoms from four bridging-bidentate 4-EBA ligands,three oxygen atoms from two chelating-bridging 4-EBA ligands,one oxygen atom from one neutral 4-EBAH hgand and one from the coordinated water molecule in a distorted tricapped trigonal-prismatic geometry.The adjacent La3+ ions are linked by the carboxylate groups of 4-EBA ligands in the bridging-bidentate or chelating-bridging coordination mode,resulting in an infinite chain structure.The hydrogen bonds involving the water molecules,carboxylate groups and carboxyl H atoms are formed within the one-dimensional polymer,Viewed along a axis,two kinds of weak π…π interactions between the benzene rings of the neighiboring chains connect the paralleling 1D chain into 2D layer structure.The luminescent property in solid state of complex was also studied and discussed.The intense blue fluorescence emission of the complex is attributed to the π→π* electron transition of the ligands.