[Eu_2(BA)_6(bipy)_2]的晶体结构和荧光光谱

CRYSTAL STRUCTURE AND LUMINESCENCE OF [Eu 2(BA) 6(bipy) 2]

标题配合物晶体属单斜晶系，Ｐ２１／ｎ空间群，晶胞参数ａ＝１．４１６２（３）ｎｍ，ｂ＝１．５３７７（５）（ｎｍ），ｃ＝２．６０１７（５）ｎｍ，β＝１０３．５６（３°），Ｚ＝４。标题配合物是双核分子，４个苯甲酸的羧基桥联两个中心Ｅｕ（Ⅲ）离子。它们又分别与１个苯甲酸的羧基的两个氧原子和一个联吡啶分子的两个氮原子螯合配位，形成４，４′－双帽三角棱柱体。两个Ｅｕ（Ⅲ）离子的Ｅｕ－Ｏ和Ｅｕ－Ｎ平均键长不等。两个Ｅｕ（Ⅲ）离子的化学环境略有不同。在配合物的７Ｆ０→５Ｄ０激发光谱里，５８０．１７和５８０．３１ｎｍ处呈现两个锐峰，可以认为配合物具有两种Ｅｕ（Ⅲ）格位，选择激发配合物的５Ｄ０能级，得到的５Ｄ０→７Ｆ１，２发光光谱表明配合物中Ｅｕ（Ⅲ）离子有不同的化学环境，这与晶体结构分析结果一致。

Crystal of the new title complex [Eu 2(BA) 6(bipy) 2] (BA: benzoate, bipy: bipyridine) crystallizes in monoclinic, P2 1/n space group with cell parameters a=1.4162(3) nm, b =1.5377(5) nm, c =2 6017(5) nm, β =103.56(3)°, Z=4. The complex is a binuclear molecule with the four bridged carboxylato groups of the benzoic acid bonded to the two europium ions, each ion is also chelated with the two oxygen atoms of a molecule of the benzoic acid and the two nitrogen atoms of a bipyridine molecule respectively, forming a 4,4′ bicapped trigonal prism. Average Eu O and Eu N distances of the two Eu(Ⅲ) ions are unequal. This shows the two europium ions are in different chemical environments. In a 7F 0→ 5D 0 excitation of spectrum of the complex two sharp peaks are at 580 17 and 580.31 nm. This indicates two Eu(Ⅲ) sites are involved in the complex. It is confirmed by selectively excited 5D 0 emission states of each Eu(Ⅲ) sites. This is in agreement with results of X ray analysis.