摘 要:作为超分子化学领域中的基本构建规则和重要目标，分子识别和分子自组装一直被 研究者们广泛关注。基于阴离子对医学、生物学、环境和材料等领域的重要作用，设计 合成检测、分离和识别特定阴离子的功能受体是十分必要的，然而阴离子复杂的构型使 得这一研究充满挑战。本文论述了基于 3, 5-二氨基吡啶多脲衍生物的合成、表征及阴离 子识别研究。主要工作如下：

（1）合成并表征了基于 3, 5-二氨基吡啶衍生的多脲类受体 L1 (C33H27N11O8)和 L2 (C19H15N7O6)。以 3, 5-二氨基吡啶为起始反应物和 2-硝基苯异氰酸酯反应制备中间产物 化合物 A (C19H15N7O6)，以水合肼为还原剂，将化合物 A 还原得到中间产物化合物 B (C19H19N7O2)，最后将化合物 B 和 4-硝基苯异氰酸酯反应制得 3, 5-二氨基吡啶衍生四脲 受体 L1；以 3,5-二氨基吡啶为原料与 4-硝基苯异氰酸酯一步合成 3, 5-二氨基吡啶衍生 二脲受体 L2。对合成产物利用核磁共振、元素分析和红外光谱等手段进行结构表征，所 得表征数据证实所合成产物即为目标产物。在多种非质子性溶剂中进行 L1 和 L2 的溶解 度测试，并进行了 L1和 L2 与一系列的四丁基季铵盐（TBA 阴离子盐）的反应，采取液 相扩散法的方式分别培养了受体 L1 与 TBACl（四丁基氯化铵）和 TBAF（四丁基氟化 铵）配合物的单晶。

（2）研究了吡啶四脲受体 L1 的 TBACl 配合物 (1: C68H105Cl2N13O9) 和 TBAF 配合物 (2: C65H99F2N13O8) 的固态性质。X-射线单晶衍射数据表明，两个配体分子 L1 形成的二聚 体带有两个合适的空腔，每个空腔通过多重 N-H···Cl 氢键将两个 Cl -阴离子包夹。该二 聚体进而通过 C-H···O 氢键和 C-H···Cl 氢键拓展为二维网络结构。配合物 2 具有与配合 物 1 类似的结构。利用 X-射线粉末衍射和元素分析检测了所制备的配合物粉末的纯度。 在核磁共振氢谱中和外红光谱中研究了发生主客体相互作用时引起的谱图变动。通过 TG-DTG 的方式研究了配体 L1、配合物 1 和配合物 2 在三种加热速率下的热分解过程， 并计算了三者在主要分解过程的表观活化能 Ea，结果表明 Ea (1)＞Ea (2)＞Ea (L 1 )。

（3）研究了 3, 5-二氨基吡啶衍生多脲受体 L1 和 L2 对不同阴离子的识别作用。通 过紫外竞争选择性实验和裸眼识别实验探究 L1 和 L2 与不同阴离子结合的响应灵敏度， 结果显示，L1 对 SO4 2-、F -和 Cl-发生了不同程度的响应，而 L2 对 SO4 2-和 F -发生响应， 其中以 SO4 2-引起的变化最为明显。为了进行定量检测，本文探究了受体 L1 和 L2 与上述 有响应阴离子的结合性能。利用紫外可见光谱进行的 Job 曲线研究表明，配体 L1 与 F - 和 Cl-阴离子的结合比均为 1:2，紫外滴定实验结果表明，配体 L1 与 F -阴离子的结合常 数为：K1 = 1.5 × 105 M-1，K2 = 4.55 × 103 M-1；配体 L1 与 Cl-阴离子的结合常数为：K1 = 9.83 × 104 M-1，K2 = 1.05 × 103 M-1。主客体化学研究表明配体 L1 与 SO4 2-阴离子的结合 比为 1:1，结合常数为 8.01 ×105M-1。L2 与 SO4 2-和 F -的结合比均为 1:1，L2 与 SO4 2-和 F - 的结合常数分别为 1.24 × 105 M-1 和 6.61 × 104 M-1。

这些研究为吡啶脲类受体对特定阴离子的识别检测提供了新的思路，同时也为探究 多阴离子系统的本质规律提供了一定的理论参考。

ABSTRACT: As the basic construction rules and important goals in the field of supramolecular chemistry, molecular recognition and molecular self-assembly have been widely concerned by researchers. Considering the importance of anions to medicine, biology, environment and materials, it is necessary to design and synthesize functional receptors that can detect, isolate and recognize specific anions. However, the complex configuration of anions makes this research challenging. This paper discusses the synthesis, characterization and anion recognition of 3, 5-diaminopyridine polyurea derivatives. The main work is as follows:

(1) The 3, 5-diaminopyridine derived polyurea receptors L1 (C33H27N11O8) and L2 (C19H15N7O6) were synthesized and characterized. The intermediate compound A (C19H15N7O6) was prepared by reacting 3, 5-diaminopyridine as the starting reactant with 2-nitrophenyl isocyanate. The intermediate compound B (C19H19N7O2) was obtained by reducing compound A with hydrazine hydrate as the reducing agent. Finally, the reaction of compound B with 4- nitrophenyl isocyanate afforded 3, 5-diaminopyridine derived tetraurea receptor L1 . The 3, 5- diaminopyridine derived diurea receptor L2 was synthesized in one step from 3, 5- diaminopyridine and 4-nitrophenyl isocyanate. All the synthesized products were characterized by 1H NMR, elemental analysis and infrared spectroscopy, and the characterization data proved that the synthesized products were the target products. The solubility of L1 and L2 was tested in a variety of aprotic solvents. The reaction of L1 and L2 with a series of tetrabutylquaternary ammonium salts were carried out at room temperature. The single crystals of complexes of the acceptors L1 with TBACl and TBAF were cultured by liquid phase diffusion method, respectively.

(2) The solid state properties of the TBACl complex (1: C68H105Cl2N13O9) and TBAF complex (2: C65H99F2N13O8) of the pyridine tetraurea receptor L1 were studied. X-ray single crystal diffraction data show that the dimer formed by the two ligand molecules L1 bears two suitable cavities, each of which encapsulates two Clanions by multiple N-H···Cl hydrogen bonds. The dimer is further developed into a two-dimensional network structure by C-H···O hydrogen bond and C-H···Cl hydrogen bond. Complex 2 has a similar structure to complex 1. The purity of the prepared complex powders were measured by X-ray powder diffraction and elemental analysis. The spectral changes caused by host guest interactions were studied in 1H NMR spectra and infrared spectroscopy. Further, the thermal decomposition processes of ligand L1 , complex 1 and complex 2 were studied by TG-DTG method at the heating rate of 5, 10 and 15℃·min-1 , and the apparent activation energies Ea was calculated for all three in the main decomposition process. The results showed that Ea (1) > Ea (2) > Ea (L 1 ).

(3) The recognition of different anions by 3,5-diaminopyridine derived polyurea receptors L1 and L2 was studied. The response sensitivity of L1 and L2 to the binding of different anions was investigated by UV competitive selectivity experiment and naked eye recognition experiment. and the results showed that L1 responded to SO4 2- , Fand Clto varying degrees, while L2 responded to SO4 2- and F- , with SO4 2- causing the most pronounced changes. For quantitative detection, the binding properties of receptors L1 and L2 to the above responsive anions were investigated. The Job plot study using UV-vis spectra shows that the binding ratio of ligand L1 to Fand Clanions is 1:2. The UV titration results show that the binding constants of ligand L1 to Fanion are K1 = 1.5 × 105 M-1 , K2 = 4.55 × 103 M-1 . The binding constants of ligand L1 to Clanion are K1 = 9.83 × 104 M-1 , K2 = 1.05 × 103 M-1 . The host-guest chemistry study showed that the binding ratio of L1 to SO4 2- anion was 1:1, and the binding constant was 8.01 ×105 M-1 . The binding ratio of L2 to SO4 2- and Fis 1:1, and the binding constant of L2 to SO4 2- and Fare 1.24 × 105 M-1 and 6.61 × 104 M-1 , respectively.

These studies provide a new idea for the identification and detection of specific anions by pyridine-urea receptors, and also provide a certain theoretical reference for exploring the essential regularity of polyanion system.