可溶性铂（II)配合物自组装体系的开发及其发光性能研究

Square planar platinum (II) complexes with phosphorescent emission have attracted numerous research interests due to their intriguing spectroscopic properties as well as great potentials in organic light emitting diodes (OLEDs), chemosensors and biosensors, cell imaging and self-assembly. Square-planar platinum (II) complexes containing π-conjugated ligands are particularly attractive building blocks for self-assembly reactions, because cofacial molecular aggregation can maximize the orbital interactions between two π systems, thus leading to rich photophysical and photochemical properties that can be harnessed for optoelectronic applications and light-energy conversion reactions. Intermolecular PtoooPt interactions play a key role in the close packing of molecules. Terpyridine ligands and their C^N^N, N^C^N analogues have been coordinated to platinum, leading to neutral, mono-, or doubly charged species, some of which display bright luminescence. They can form supramolecular structures, such as nanowires, nanosheets, and polymeric mesophases, with interesting optical properties. On the other hand, pyrimidine derivatives are good electron transport materials due to their having high electron affinities. Pyrimidine molecule contains some empty π* orbital, which could accept electron density from a soft metal like Pt(II), but the nature of spectroscopic and self assembly of the platinum containing pyrimidine has not been studied in the literature. Rod-coil molecules, consisting of a flexible and a rigid block, have a strong capacity to self-assemble into a variety of ordered nanostructures in the bulk state. In the project, we combine the advantages of both the platinum complexes and the rod-coil molecules, and design a series of new rod-coil platinum complexes containing pyrimidine, and study their correlation of their spectroscopic behaviour and self-assembly structure, and reveal basic rules between self-assembly structure and photochemistry from molecular level. Furthermore, this project presents the potential applications of platinum (II) complexes in bioimaging as phosphorescent probes.

平面四方配位构型铂(II)配合物具有发光效率高、发光波长可调、发光寿命长等优点，在发光材料领域具有广阔的应用前景。本项目拟通过在配体分子中引入含有缺电子的嘧啶基团，稳定铂配合物LUMO能级的同时，降低HOMO-LUMO能隙，从而获得吸收和发射光谱红移的发光材料；另外，赋予分子刚性(Rod)和柔性链(Coil)结构，在提高配合物溶解性的基础上，增强其自组装能力，构筑具有规整形状的纳米结构，考察铂(II)配合物在稀溶液状态、固态和自组装状态时的发光行为，研究铂(II)配合物的发光性质与分子结构及不同自组装方式的相关性和机理，从分子层次揭示自组装结构和材料光化学性能之间的基本规律。并在此基础上，进一步探讨铂(II)配合物作为磷光探针在生物成像中的应用。

本项目通过研究铂(II)配合物的分子结构和自组装方式与其发光性能之间的关系为进一步设计、制备相关的功能材料奠定了基础。主要研究内容包括：(1)两个含嘧啶基团的N^C^N三齿配位环金属化铂(II)配合物的合成，通过改变取代基调控刚性链段和柔性链段的比例实现了对其自组装行为的调控，在不良溶剂中得到发橘黄色荧光的黄色固体，而在良溶剂中得到发红色荧光的棕色固体。(2)两亲性棒线型铂(II)配合物的合成，带有四条OTEG链的铂(II)配合物在甲醇溶液中和石英片上先形成二聚体再自组装成规整的二维膜，由于存在Pt···Pt和π-π相互作用发射红色荧光；而带有两条OTEG链的铂(II)配合物自组装成发黄色荧光的二维片层结构。研究结果表明刚性链段和柔性链段之间的比例在自组装过程和发光性能方面发挥了重要的作用。(3)利用配位键导向自组装法合成了四方形和三角形有机铂(II)大环化合物，研究结果表明刚性骨架的配体有利于形成四方形大环而相对柔性的配体利于形成三角形大环结构。(4)利用反式偶氮苯能够进入β-环糊精空腔而顺式偶氮苯不能的原理制备了光控可逆[2]索烃，同时利用配位键导向自组装和主客体相互作用的原理大大方便了由简单组分制备结构复杂的机械互锁分子。(5)在利用Suzuki-Miyaura反应合成配体的过程中意外得到了单体、二聚体、三聚体、四聚体硼酸酯，且这些硼酸酯可以不用分离直接用于Suzuki反应制备一系列芳香烃衍生物，该法在有机化学、药物化学等领域具有潜在的应用前景。(6)以Co2(CO)8为催化剂，含嘧啶基的苯炔衍生物可以发生三聚反应得到爪形结构的六芳基苯衍生物，当与Ag+, Cu2+和Zn2+作用后可以得到球形、纤维状结构和带状结构的自组装体。(7)合成了含三个嘧啶基的六杂芳基苯衍生物，C3-对称的六杂芳基苯自组装成羊毛状结构，与Ag+作用后变成带状结构；而不对称的六杂芳基苯与Ag+作用前后形貌没有发生变化，说明分子构型在自组装和离子配位方面扮演重要的角色。以上研究结果对铂(II)配合物可控自组装方面的研究起到极大的推动作用，为此类材料的开发、应用奠定了坚实的基础。