新型氯桥连一维链结构Cd(Ⅱ)配位聚合物的合成、 结构及蓝光性能

利用2-乙酰基吡啶(acpy) 和2-邻甲基苯胺在甲醇中回流反应得到新型希夫碱配体2-{1-(2-甲基苯基) 亚氨基]-乙基}吡啶)(mpep) , 通过溶剂热法将acpy和mpep与氯化镉反应得到2种新型氯桥连一维之字链结构Cd(Ⅱ) 配位聚合物{Cd(mpep) ]Cl₂}_n(配合物1)和{Cd(acpy) ]Cl₂}_n(配合物2). 利用单晶X射线衍射、 核磁共振氢谱、 元素分析和红外光谱对配合物1和配合物2进行结构表征. 结果表明, 配合物1和配合物2均为一维之字链状结构. 在配合物1中, Cd与mpep配体中2个氮原子和4个氯原子配位, 呈六配位顺式八面体构型, 并通过2个Cl原子桥连形成一维之字链状结构. 在配合物2中, 中心金属Cd(Ⅱ) 与acpy中的氮原子、 氧原子和4个氯原子配位, 也呈六配位顺式八面体构型, 进一步通过Cl原子桥连相邻金属形成一维之字链状结构. 在3种不同极性的溶剂(CH₃OH, CH₃CN和 CH₂Cl₂)中, 两种配位聚合物均呈现蓝色荧光(390~433 nm) , 说明2种配位聚合物具有弱溶剂效应; 在固态室温下两种配位聚合物也呈现蓝色荧光, 最大发射波长分别为440和473 nm. 固态最大发射波长比溶液中红移的原因是分子中存在氢键, 降低了基态与激发态之间的能级差. 在室温下, 配合物1和配合物2在3种溶液和固态中均显示出较长的荧光寿命(19.08~60.20 μs) .

Synthesis,Characterization and Blue-emission of Cd(Ⅱ)Coordination Polymers with μ-Chlorine-Bridging One-dimensional Chain Structures†

Two coordination polymers, {Cd(mpep)]Cl₂}_n(1, mpep=2-{1-(2-methylphenyl)imino]-ethyl}pyridine) and {Cd(acpy)]Cl₂}_n(2, acpy=2-acetylpyridine), were synthesized under solvothermal condition. The structures of complexes 1 and 2 were characterized by single crystal X-ray diffraction analysis, ¹H nuclear magnetic resonance(¹H NMR) spectrometry, elemental analysis and infrared(IR) spectrometry. The results show that both complexes 1 and 2 have 1D chain structure. The central cadmium(Ⅱ) atom in complex 1 is coordinated by four chloride ions and two nitrogen atoms from mpep, forming a distorted cis-octahedron coordination geometry, and the Cd(mpep)]Cl₂ unit builds up a polymeric chain by μ₂-chlorine-bridging. The central cadmium(Ⅱ) atom in complex 2 is coordinated by a nitrogen atom and an oxygen atom from acpy and four chloride ions, forming a distorted cis-octahedron coordination geometry, the Cd(acpy)]Cl₂ unit builds up a polymeric chain by μ₂-chlorine-bridging. Additionally, the fluorescent properties of the two complexes were characterized in both solid state and in different polar solvents. The results show that com-plexes 1 and 2 exhibit blue fluorescence emission(ca.390—433 nm) in CH₃OH, CH₃CN and CH₂Cl₂, indicating that the coordination polymers have weak solvent effect. The emission spectra of complexes 1 and 2 at 298 K are centered at 440 and 473 nm respectively in solid state. Comparing to the emission spectra in solutions, the emission spectra in solid-state undergo obvious red-shift. The lifetime of complexes 1 and 2 are relatively long(ca.19.08—60.20 μs) at room temperature.