Construction And Application Of Supramolecular Functional Systems Constructed By Pillar[5]Arene-based Pseudorotaxanes

As the simplest type of mechanically interlocked molecules(MIMs),pseudorotaxanes have attracted tremendous attention due to their fundamental roles in synthesizing complex molecular machines and constructing supramolecular materials.For their natural structures,without the blocking groups at the end of axle to inhibit the macrocyclic molecules slipping out,the pseudorotaxanes exhibit excellent properties in extermal-stimuli behaviors.Thus,it is essential to fabricate pseudorotaxanes with different topological structures for the investigation of their dynamic behaviors and their potential applications in constructing functional supramolecular materials,which plays a vital role in the development of supramolecular chemistry.According to the above research frame,the research content of this dissertation mainly includes the following six aspects:In chapter 1,the important role and position of pseudoroaxanes in supramolecular chemistry are summarized,and the pseudorotaxanes constructed by the common types of macrocyclic host molecules are illustrated,as well as their stimuli-responsive behaviors to temperature,polarity of the solvent,and external stimuli.Furthermore,the functional supramolecular systems based on this type of MIMs are also presented.In chapter 2,a mono-biotin-functionalized pillar[5]arene 2-1 was synthesized by the click reaction,which could form a stable pseudo[1]rotaxane 2-1' in non-polar or weak-polar solution.Interestingly,the obtained pseudo[l]rotaxane 2-1' exhibited a dynamic slow disassembly process within NMR timescale upon adding strong-polar solvent or competitive guest.Moreover,this dynamic behavior also had potential application in aqueous solution,which might be used as a switch to turn on or off the bioactivity of biotin moiety.In chapter 3,mono-alkyl-functionalized pillar[5]arenes 3-1,3-2,and 3-3 were synthesized by click reaction,which exhibited different self-assembly behaviors in polar solvent DMSO.Stable pseudo[1]rotaxane was formed by the self-complexation from 3-1 or 3-2,whereas,eoncentration-dependent pseudorotaxane structures were generated by P3 which bearing a more flexible side chain.Interestingly,the obtained pseudo[1]rotaxanes exhibited a dynamic fast assembly process upon adding NaBF4,resulting in the formation of Na+-induced pseudorotaxanesIn chapter 4,a stable pseudo[2]rotaxane was formed in CHCl3 between pyridine derivative guest 4-1 and DMP5 by host-guest interaction,which could form linear supramolecular polyrotaxane by the incorporation of metal-ligand coordination after adding Pd(OAc)2 to the solution.Due to the hydrogen bonding between the linear polyrotaxanes,a supramolecular gel could be formed in the concentrated solution,exhibiting multi-responsiveness to external stimuli.The reversible sol-gel transformation could be achieved by thermal-and diluting-stimuli,while competitive ligand such as PPh3 would induce the irreversible exchange.In chapter 5,novel GSH-and pH-responsive supramolecular vesicles constructed by an amphiphilic inclusion complex formed by water-soluble pillar[5]arene and lysine derivative 5-1 have been successfully developed,which can efficiently encapsulate antieancer drug MTZ and show rapid MTZ-release in a simulated acidic tumor environment with high GSH concentration,and exhibit potent antitumor activity.In chapter 6,two prodrag-based guest molecules containing disulfide bond were synthesized as the guest molecules to construct nanoparticles with the biotin-functionalized water-soluble pillar[5]arene H,in which the active drugs were camptothecin(CPT)and chlorambucil,respectively.The CPT-based guest molecule 6-1 could self-assemble into nano-sheet structures,to which the further addition of H would result in the precipitation of white membrane-like precipitate.And the chlorambucil-based guest molecule 6-2 could assemble into supramolecular micelles in the presence of H.Furthermore,anticancer drug CPT could be encapsulated into the hydrophobic core of the obtained nanoparticles and achieved successfully drug release with the extermal stimulus of GSH.In summary,a series of pseudorotaxanes have been synthesized by using pillar[5]arene derivatives as the host molecules to investigate their dynamic behaviors,as well as to fabricate functional supramolecular systems,such as polyrotaxanes and nano drug delivery systems,which may find great potenital applications in the construction of functional materials.