新型吡啶衍生物及其稀土配合物的合成、表征与荧光性能研究

【作者】 陈哲；

【导师】 罗一鸣；

【作者基本信息】 中南大学 ， 有机化学， 2007， 硕士

【摘要】 吡啶-2，6-二甲酸衍生物作为荧光敏化剂与稀土离子(Tb³⁺、Eu³⁺等)螯合形成配合物的荧光敏化发光性能比水杨酸和邻菲啰啉二酸的敏化效果要好。稀土离子(Tb³⁺、Eu³⁺等)-β-二酮配合物通过有机配体的强紫外吸收和配体向稀土离子的有效能量传递，使其发出稀土离子的强特征荧光，具有较好的紫外激发荧光性能。因此，设计并合成新型的吡啶-2，6-二甲酸衍生物，尤其双β二酮类化合物及其衍生物，对于寻找和开发新型稀土离子发光敏化剂具有重要意义，同时设计配体的分子结构也是寻找新型稀土离子发光敏化剂的关键。本文设计了一系列未见文献报道的具有较大的π共轭体系的双β二酮类有机配体及其衍生物双吡唑类化合物。以具有较强荧光敏化发光性能的吡啶-2，6-二甲酸（L₁）为起始物，先经甲醇酯化保护羧基，再经过一类似Claisen酯缩合的反应成功合成了一种新型的双-β-二酮中间体2，6-二苯甲酰乙酰基吡啶（L₇），继而将其分别与水合肼和苯肼缩合得两种新型双吡唑化合物2，6-双[（3-吡唑基）-5-苯基]吡啶（L₈）和2，6-双[（3-吡唑基）-3，5-二苯基]吡啶（L₉），以上三种新型配体的结构通过IR、EA、¹H-NMR和GC-MS等现代物理方法得以表征。本文制备了2，6-二苯甲酰乙酰基吡啶（L₇）与稀土离子Tb³⁺、Eu³⁺、Gd³⁺和Sm³⁺形成的配合物，通过元素分析及红外光谱初步确定了配合物可能的组成和结构，对四种配合物固体的荧光强度进行了比较，发现该配体能很好的敏化Tb³⁺离子发光，为其较理想的荧光敏化剂。同时还分别制备了配体L₈和L₉与稀土离子Tb³⁺的配合物，荧光测试表明，配体L₈能很好地敏化Tb³⁺发光，是一种较好的荧光敏化剂。此外，为了寻找和开发新型有机荧光敏化剂，根据有机荧光敏化剂的特点和分子设计的原理，设计并成功地合成了另一系列新型的吡啶-2，6-二甲酸衍生物：吡啶2，6-二甲酰肼（L₃）、呋喃甲醛缩吡啶-2，6-二甲酰肼（L₄）、苯甲醛缩吡啶-2，6-二甲酰肼（L₅）、水杨醛缩吡啶-2，6-二甲酰肼（L₆）。上述四种新型配体的结构通过IR、EA、¹H-NMR和GC-MS等现代物理方法得到表征。并制备了L₃、L₄、L₅和L₆与稀土Eu³⁺和Tb³⁺离子的配合物。结果表明：以上四种配体均能不同程度地敏化稀土Eu³⁺和Tb³⁺离子发光；具有较大的π共轭体系的有机配体的荧光敏化性能要优于共轭体系小的配体；具有供电子基的配体的荧光敏化性能要优于具有吸电子基的配体；在水溶液中稀土配合物与溶液的pH值有密切关系，在pH=7的中性水溶液中荧光强度较大，在酸性和碱性水溶液中配合物荧光强度都较小；不同溶剂的配合物溶液荧光强度相比较，在分子偶极矩较小的溶剂中，稀土配合物荧光强度较强。更多还原

【Abstract】 Pyridine-2,6-dicarboxylic is the best sensitizer of the lanthanide (Tb³⁺, Eu³⁺ ions) than salicylic , phenanthroline. And the lanthanide complexes with-β-diketone-kind ligands are of high ability of UV-vis exicitation fluorescence, and the ligands make rare earth ions emit strong characteristic fluorescence by organic ligands’strong UV-vis absorbance and efficienct energy-transfer between the ligands and ions. Therefore,designing and synthesizing novel pyridine-2,6-dicarboxylic derivatives, especially di-β-diketone-kind compounds and their derivatives, is of great importance for searching and developing novel sensitizers for rare earth ions with pyridine-2,6-dicarboxylic as a starting material,and designing the structures of ligands is also a key point to discover new rare-earth ions fluorescent sensitizersIn this paper , a list of di-β-diketone organic ligands and their di-pyrazole derivatives which were not reported by references so far, and have big n-conjugated system were designed,and a novel di-β-diketone organic intermediate 2,6-bisbenzoylactyl pyridine （L₇） was synthesized by esterification and Claisen Condensation reaction using pyridine -2,6-dicarboxylic dacid which is a better fluorescent sensitizer as starting material and its two derivatives 2,6-di[（3-pyrazolyl）-5-phenyl] pyridine （L₈） and 2,6-di[（3-pyrazolyl）-3,5-diphenyls] pyridine （L₉） were successfully obtained by Condensation reaction with hydrazine hydrate and phenylhydrazine respectively, the above three novel ligands were confirmed by IR, ¹HNMR, GC-MS and EA. The Tb³⁺、Eu³⁺、Gd³⁺and Sm³⁺ complexes of ligand L7 were prepared. The possible structures of the above complexes were deduced by EA and IR roughly. The fluorescence properties of the solid complexes were investigated in detail,and the ligand L7 was proved to be a better sensitizer for Tb³⁺ and Eu³⁺. The Tb³⁺ complexes with ligand L₈ and ligand L9 were also preparedand charactered ,and ligand L₈ was found to be a better sensitizer for Tb³⁺ ions.Furthermore, in order to find and develop new organic fluorescence sensitizers, another list of novel pyridine-2,6-dimethylhydrazine and its derivatives pyridine-2,6-dimethylhydrazones organic ligands: furfurol-pyridine-2,6-dimethylhydrazine （L₄）、benzaldehyde-pyridine-2,6-dimethylhydrazine （L₅） and salicylaldehyde - pyridine -2,6- dimethyl hydrazine （L₆） were synthesized successfully according to the design of molecule and the characteristic of organic fluorescence sensitizers, the above four novel ligands were confirmed by IR, ¹HNMR, GC-MS and EA. The Tb³⁺、and Eu³⁺ complexes of the four ligands were prepared.The contradistinctive experimental results show that the above four ligands can sensitize Eu³⁺ and Tb³⁺ ions to some extent; The ligand which has larger conjugate system is a better fluorescence sensitizer than the smaller conjugate system ligands, the fluorescence of the complexes with electron-donating groups is more intense than that of the complexes with electron-withdrawing groups; When the pH value is about at 7,fluorescence intensities of the complexes are strongest; while the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is;更多还原