三个稀土-主族三金属Ln(Ⅲ)-Sr(Ⅱ)-K(Ⅰ)配合物的结构与发光性质

Structures and Luminescent Properties of Three Heterotrimetallic Ln(Ⅲ)-Sr(Ⅱ)-K(Ⅰ) Complexes

用2,4,6-吡啶三甲酸和稀土钐、镝或钆的高氯酸盐溶液、碳酸锶、碳酸钾在180℃水热条件下进行反应,制备出3个含有3种金属离子的配位聚合物[Ln Sr K(ptc)2(H2O)]n(Ln=Sm(1)、Dy(2)、Gd(3),H3ptc=2,4,6-吡啶三甲酸)。X射线单晶衍射分析表明三者具有相同的结构,属三斜晶系,P1空间群。配合物中配体2,4,6-吡啶三甲酸根以2种不同的配位方式与3种金属离子配位,一种方式中连接了7个金属离子,另一种方式中连接了8个金属离子。Ln(Ⅲ)为八配位,与羧基上的6个氧原子和2个吡啶环上的2个氮原子配位;Sr(Ⅱ)也是八配位,配位原子均为氧原子;K(Ⅰ)与5个氧原子配位。荧光发射光谱表明,钐和镝的配合物在紫外光激发下均发射Sm(Ⅲ)和Dy(Ⅲ)两种离子的特征荧光,钆的配合物在紫外光激发下由于发生荷移跃迁而发射绿色荧光。

Three coordination polymers with the molecular formula[LnSrK(ptc)2(H2O)]n(Ln=Sm(1),Dy(2),Gd(3),H3ptc=2,4,6-pyridinetricarboxylic acid)were synthesized by hydrothermal reaction of the solutions of Ln(ClO4)3,SrCO3,K2CO3 and H3ptc at 180℃.The structures of three complexes were determined by X-ray single crystal diffraction and the results showed they are isomorphic compounds and crystallize in triclinic system,P1 space group.The ptc ligands bonded with three metal ions Ln(Sm(1),Dy(2)and Gd(3)),Sr,K with two types of coordination modes:connecting seven metal ions and connecting eight metal ions.Ln(Ⅲ)is eight-coordinated by six oxygen atoms from carboxyl groups and two nitrogen atoms from two pyridyl rings.Sr(Ⅱ)ion is also eightcoordinated but the coordination atoms are all oxygen atoms.K(I)is coordinated b y five oxygen atoms.The emission spectra show Sm(Ⅲ)-Sr(Ⅱ)-K⑴and Dy(Ⅲ)-Sr(Ⅱ)-K⑴complexes both emit the characteristic fluorescence of Sm(Ⅲ)and Dy(Ⅲ).The Gd(Ⅲ)-Sr(Ⅱ)-K⑴complex emits green fluorescence but it is resulted from the charge transfer transitions between the ligands and Gd(Ⅲ).CCDC:1566176,1;1566177,2;156617 8,3.