自组装磁性超分子的构筑及其与腐殖质/农药相互作用

The heterosupramolecule composed of cyclodextrin and ferroferric oxide is a kind of “green chemistry” nanomaterials, which endowed with the molecular recognition ability and magnetic property. In this project, we plan to synthesize four cyclodextrin derivatives with different flexible chain length in the substituent, build the magnetic heterosupramolecules with high-loading cyclodextrins by the bioinspired catecholic self-assembly technique, investigate the influence of the cyclodextrin-substituent’s conformational characteristics on the self-assembly behaviors and the loading amount of the cyclodextrin onto the nanoparticle, and regulate the pesticide adsorption capacity of the cyclodextrin-based magnetic heterosupramolecule by changing the flexible joint chain length between cyclodextrin and magnetic nanoparticle. Then, the mechanism for the host’s conformation having effects on the formation of its self-assembled monolayers onto the nanoparticle and the formation of the heterosupramolecule will be proposed. Moreover, the adsorption behaviors of the cyclodextrin-based magnetic heterosupramolecule to pesticide molecules will be also studied, especially in the presence of the natural water’s organic matter: humic substances, and the characteristics and mechanisms of host-guest interactions in magnetic heterosupramolecule/ humic substances/ pesticide ternary system will be proposed. The work performed in this project could provide not only the theoretical foundation for the design of the host-based heterosupramolecule and the regulation of its function realization, but also the researching support for the application of the heterosupramolecular materials in reality and complex system.

环糊精四氧化三铁非均相超分子是一类兼具客体包结能力与磁性的“绿色化学”纳米材料。本项目拟设计合成4种取代基柔性链长度不同的环糊精衍生物，利用贻贝仿生的自组装技术构筑具有高环糊精负载量的磁性超分子，考察环糊精取代基构象对其在磁性纳米粒子上自组装行为和负载量的影响，并通过改变环糊精和四氧化三铁纳米粒子间的桥链调控环糊精磁性超分子材料对农药的吸附能力。在此过程中，阐明主体分子微观构象对其自组装单分子层形成以及磁性超分子构筑的影响机制。同时，研究在水体腐殖质存在时环糊精磁性超分子对农药分子的吸附行为，揭示腐殖质所起的作用，阐明环糊精磁性超分子/腐殖质/农药三元体系中主客体相互作用的特点。本项目研究工作的开展可为功能主体类非均相超分子材料的组装设计、功能调控提供理论基础，也为该类材料在现实环境、复杂体系中的应用开发提供研究依据。

主体分子与纳米粒子形成的非均相超分子体系是超分子化学研究的新热点，特别其在复杂环境中与客体的相互作用正引起研究者的关注。本项目以腐植酸-环糊精-TiO2三元超分子体系为对象，重点研究了其对不同结构客体分子的包结及光降解行为。在项目中，我们制备了一系列具有不同长度柔性链原儿茶酸单修饰-β-环糊精，以及Fe3O4@ SiO2、Fe3O4@ SiO2@ TiO2纳米粒子，从而构筑了一系列对客体具有对吸附-光催化降解能力的环糊精-TiO2磁性超分子体系；进而，研究了腐植酸-环糊精-TiO2体系对不同结构的客体的包结及光降解行为，还对不同来源的多种腐殖酸体系的稳态及瞬态荧光光谱进行了分析。研究表明：借助环糊精上的邻苯二酚基团与TiO2纳米粒子键合可以构筑高环糊精覆盖度的环糊精-TiO2非均相超分子体系，同时TiO2组分的引入也赋予该体系光催化降解客体分子的能力；腐殖酸是一个含多寿命、多生色基团的复杂体系，对于腐植酸-环糊精-TiO2三元超分子体系，环糊精和腐植酸的包结作用减小了客体分子与二氧化钛表面腐植酸结合的几率，并减弱了腐植酸对客体分子的敏化分解效率。本项目的研究方法与成果有助于人们更深入认识多元非均相超分子体系中的相互作用。