锌（Ⅱ）-钕（Ⅲ）稀夫碱配合物的合成、晶体结构与近红外发光性质研究

【作者】 毕卫宇；

【导师】 宋纪蓉；

【作者基本信息】 西北大学 ， 化学工程， 2009， 博士

【摘要】 由于在传感器、激光、光纤通讯、荧光成像等方面具有显著应用价值,镨（Ⅲ）、钕（Ⅲ）、铒（Ⅲ）、镱（Ⅲ）等镧系金属离子配合物所发射的近红外（NIR）光近年来日益吸引着人们的兴趣和关注。为了克服镧系金属离子中宇称禁阻的f-f跃迁导致消光系数较低的不足,人们通常使用具有强吸光能力的发色团作为天线来敏化其近红外发光。本论文中采用锌离子的稀夫碱配合物作为天线来敏化钕离子的近红外发光,通过采用“配合物作配体”和“结点-连接臂”方法合成了二十个新的异双核或异多核的锌（Ⅱ）-钕（Ⅲ）稀夫碱配合物,其晶体结构全部由X射线单晶衍射确定,研究了其光致近红外发光性质,并从中选择发光性质较好的配合物制作了有机发光二极管（OLED）考察了相应的电致近红外发光性能。为了优化钕离子周围的配位环境使其远离可以导致近红外发光部分淬灭的高能振荡基团,如含有羟基的溶剂分子等,本论文首先在锌离子的轴向位置引入吡啶分子而得到四个异双核配合物:[Zn（μ-L¹）Nd（NO₃）₃（Py）]·MeCN（2）;[Zn（μ-L²）Nd（NO₃）₃（H₂O）（Py）]（4）;[Zn（μ-L³）Nd（NO₃）₃（Py）]（6）和[Zn（μ-L⁴）Nd（NO₃）₃（Py）]·MeCN（8）,其中配合物2,6,8中吡啶分子在锌离子的轴向配位有效消除了钕离子周围的高能振荡基团,同时重原子效应被证明对近红外发光有显著强化作用。其次通过合成两个含有手性稀夫碱的配合物:[Zn（μ-L⁵）Nd（NO₃）₂（OAc）]（10）和[Zn（μ-L⁶）Nd（NO₃）₃（DMF）₂]（12）,考察了手性配体对钕离子配位环境的影响。通过合成三个假多晶型的异双核配合物:[Zn（μ-L³）Nd（OAc）（NO₃）₂（DMF）]·Solvate（Solvate:EtOH（13）;THF（14）;MeCN（15））,本论文研究了分子间作用力对近红外发光的影响,固体近红外发射光谱表明分子间较强的π-π堆积作用对近红外发光有部分淬灭作用。通过引入4,4’-bpy和4,4’-bpe作桥联配体组装出两个异四核配合物:[Zn₂（μ-L¹）₂Nd₂（4,4’-bpy）（NO₃）₆]·Et₂O₁₆和[Zn₂（μ-L¹）₂Nd₂（4,4’-bpe）（NO₃）₆]·2H₂O（17）,其近红外发光较异双核前躯体有明显增强。当采用对苯二甲酸作为桥联配体时,在不同的溶剂体系和反应物配比时合成出三种不同结构的配合物:[Zn₂（μ-L¹）2Nd₂（1,4-bdc）（NO₃）₄（EtOH）₂]·2MeCN（18）; [Zn₄（μ-L¹）₄Nd₂（1,4-bdc）₂]（NO₃）₂·2Et₂O·4H₂O（19）和[Zn₄（μ-L¹）₄Nd₂（1,4-bdc）₂]·[Zn（μ-L¹）Nd（NO₃）₃（OAc）₂]₂（20）,其近红外发光强度按照19>20>18的顺序而递减进一步表明多发色团和多发光中心对近红外发光具有强化作用。异烟酸（HIN）作为桥联配体时,根据稀夫碱配体刚性的不同分别得到具有二维配位聚合物结构的[Zn（μ-L¹）Nd（IN）（NO₃）₂]。（21）和具有简单异双核结构的[Zn（μ-L³）Nd（IN）（NO₃）₂（DMF）]（22）。本论文也在不引入桥联配体的情况下合成了异多核配合物,在稀夫碱配体结合位点减少时得到两个异三核配合物:[Zn₂（μ-L⁷）Nd（NO₃）₃（Py）₂]·H₂O（25）和[Zn₂（μ-L⁸）Nd（NO₃）₃（Py）₂]·Et₂O·H₂0（27）,其中锌离子的轴向位置由吡啶分子配位,钕离子的配位球内无高能振荡基团。在Nd-O_phenol互补配位作用的驱动下得到两个环状四核配合物:[Zn(μ-L¹⁰)Nd（NO₃）₂（DMF）（Py）]₂·（Et₂O）₂（30）和[Zn（μ-L⁹）Nd（NO₃）₂（DMF）₂]₂（33）,并得到上述化合物中钕离子发光的内在量子产率和天线基团对钕离子的能量传递速率常数。最后本论文将配合物25（[Zn₂（μ-L⁷）Nd（NO₃）₃（Py）₂]·H₂O）掺杂入PVK中作为发光层,PEDOT-PSS作为空穴注入层制作了近红外有机发光二极管器件,器件结构为:ITO（20Ω/square）/PEDOT-PSS（70 nm）/PVK:Complex 25（30 nm）/Ca（100 nm）/Al（100 nm）,在20 V驱动电压下近红外光辐射度为1.8 nW·mm^-2,电流密度为50 mA·mm_-2,表明这类化合物在有机发光二极管中具有潜在的应用价值。更多还原

【Abstract】 Because of the significant technical applications in sensor, laser system, optical telecommunications and fluorescent imaging, near-infrared （NIR） luminescence from lanthanide（Ⅲ） complexes such as Pr（Ⅲ）, Nd（Ⅲ）, Er（Ⅲ）, Yb（Ⅲ） has attracted increasingly great interest over the last few years. For overcoming very low extinction coefficients resulting from parity-forbidden f-f transitions of lanthanides, a suitable light-harvesting chromophore as antenna to sensitise the NIR luminescence was often employed. In this thesis, the complexes of Zn（Ⅱ）-Schiff base were adopted as antenna groups for sensitizing the NIR luminescence from Nd（Ⅲ）. By the approaches of "complex as ligand" and "node and spacer", twenty new Zn（Ⅱ）-Nd（Ⅲ）-Schiff base heterobinuclear or heteropolynuclear complexes were synthesized. Their crystal structures were all determined by X-ray single crystal diffraction. Near-infrared photoluminescence properties of these complexes were studied. By selecting a complex with preferable optical property from those, an OLED was fabricated and near-infrared electroluminescence was observed.Firstly, for optimizing the coordination environment and making Nd（Ⅲ） remote from high-energy oscillators such as solvent molecule containing hydroxyl, which will quench NIR luminescence partly, pyridine was introduced as axial ligand to Zn（Ⅱ）. Four heterobinuclear complexes（[Zn（μ-L¹）Nd（NO₃）₃（Py）]·MeCN,2;[Zn（μ-L²）Nd（NO₃）₃（H₂O）（Py）],4 ;[Zn（μ-L³） Nd（NO₃）₃（Py）], 6; [Zn（μ-L⁴）Nd（NO₃）₃（Py）]·MeCN, 8） with pyridine coordinating to Zn（Ⅱ） were synthesized and high-energy oscillators were removed from Nd（Ⅲ） for the complexes 2, 6, 8 thereinto. Meanwhile heavy-atom effect was proved to be capable of enhancing NIR luminescence remarkably. Two heterobinuclear complexes with chiral Schiff base （[Zn（μ-L⁵）Nd（NO₃）₂（OAc）],10;[Zn（μ-L⁶）Nd（NO₃）₃（DMF）₂] ,12） were synthesized for illustrating the influence of chiral ligand on the coordination of Nd（Ⅲ）. The effect of intermolecular interactions on NIR luminescence was studied by synthesizing three heterobinuclear complexes with pseudopolymorphism: [Zn（μ-L³）Nd（OAc）（NO₃）2（DMF）]·Solvate（Solvate: EtOH （13）, THF （14）, MeCN （15））. Solid state NIR emission spectra indicate that strongπ-πstacking would quench NIR luminescence partly.Next, two heterotetranuclear complexes（[Zn₂（μ-L¹）₂Nd₂（4,4’-bpy）（NO₃）₆]·Et₂O,16;[Zn₂ （μ-L¹）₂Nd₂（4,4’-bpe）（NO₃）₆]·2H₂O,17） were assembled by introducing 4,4’-bpy and 4,4’-bpe as bridging ligands. Stronger NIR luminescence was observed compared with that of heterobinuclear precursor. By employing 1,4-bdc as bridging liand,[Zn₂（μ-L¹）₂Nd₂（1,4-bdc）（NO₃）₄ （EtOH）₂]·2MeCN （18）,[Zn₄（μ-L¹）₄Nd₂（1,4-bdc）₂]（NO₃）₂·2Et₂O·4H₂O （19） and [Zn₄（μ-L¹）₄-Nd₂（1,4-bdc）₂]·[Zn（μ-L¹）Nd（NO₃）₃（OAc）₂]₂ （20） were synthesized under different solvent and reaction stoichiometry. Their NIR luminescence intensity decrease according to the sequence: 19>20>18. This confirms introducing polychromophores and polyemitters may enhance luminescence intensity efficiently. When isonicotinic acid （HIN） was used as bridging ligand, 2D coordination polymer [Zn（##-L¹）Nd（IN）（NO₃）2]_n （21） and simple heterobinuclear adduct [Zn（μ-L³）Nd（IN）（NO₃）₂（DMF）] （22）, which was dependent on the rigidity of Schiff base ligand, were obtained respectively.Heteropolynuclear complexes were also prepared without introduction of bridging ligand. Two trinuclear complexes （[Zn₂（μ-L⁷）Nd（NO₃）₃（Py）₂]·H₂O,25;[Zn₂（μ-L⁸）Nd（NO₃）₃（Py）2]·Et₂O·H₂O,27） were synthesized with pyridine as axial ligand to Zn（Ⅱ） and without high-energy oscillators within the coordination sphere of Nd（Ⅲ） because of decreased binding sites of corresponding ligand. Two cyclic tetranuclear complexes ([Zn(μ-L¹⁰)Nd（NO₃）₂-（DMF）（Py）]₂·（Et₂O）₂,30; [Zn（μ-L⁹）Nd（NO₃）₂（DMF）₂]₂,33) were obtained under the driving of Nd-O_phenol complementary coordination. The intrinsic quantum yield of Nd（Ⅲ） emission and energy-transfer rate constant for these four compounds were determined.Lastly an NIR OLED device was fabricated by doping complex 25 （[Zn₂（μ-L⁷）Nd（NO₃）₃ （Py）₂]·H₂O） into PVK as emitting layer and employing PEDOT-PSS as hole-injecting layer. The structure of device was ITO（20Ω/square）/PEDOT-PSS（70 nm）/PVK: Complex 25（30 nm）/Ca（100 nm）/Al（100 nm）. A near-infrared irradiance of 1.8 nW·mm^-2 and current intensity of 50 mA·mm^-2 under driving voltage of 20 V was achieved, which demonstrates the value of potential applications in OLED for this kind of compounds.更多还原