Synthesis And Properties Study Of [2]Rotaxane Based On Urea/Guanidyl And Phosphine Oxide

During the exploration of micro-world, chemists have been trying to discover the mystery of nano materials. They hope to simulate and replace macro-world with these single molecules and supramolecular systems.Under such condition, rotaxane-based-molecular-machines, which are part of supramolecules, have been paid much attention from scientists in recent years. There exists various weak interactions between particles of the supramolecules, such as hydrogen bonding, hydrophobic effects and so on. Upon external stimuli, pH changes and radiation for instance, relative movements may happen between hosts and guests, which may result the changes of testing signals.A rotaxane is made up of macrocycle(s) and dumbbell-shaped component(s) by the weak interactions between them. The two steric groups in each side of dumbbell-shapes chains prevent the macrocycles against dethreading from the guests. If some changes were made to the system, the macrocycles might rotate or slide along the chains.According to the research results above, the content of this dissertation may include the following aspects:In the first chapter, we summarized the concept of supramoleculars and the importance of molecular machines in supramolecular system. Pseudorotaxane, rataxane and catenane based molecular machines were introduced respectively. Then we introduced the driving factors that switch the molecular machines "functioning" including pH regulation, ion regulation, electrochemical regulation, configuration regulation, optical drive and solvent change regulation. Finally, the potential applications of the molecular machines are introduced in nano materials, biologies and supramolecular catalysis fields.In the second chapter, we successfully synthesized a novel molecular machine-molecular shuttle. There were three different recognition sites, namely phosphine oxide, dibenzylammonium, and urea functional groups. To the best of our knowledge, the phosphine oxide was firstly introduced in such researches. The macrocycle can be easily switched between three different binding sites along the thread by the addition/removal of acid/base or anions, resulting in three stable states.In the third chapter, we changed the join order of the three recognition sites compared to the shuttle in chapter 2, that is to say, the urea recognition sites is moved between phosphine oxide and dibenzylammonium groups.In addition, three long alkyl chains were introduced to one side of the guest. Initial explorations of gelation ability have been done to this rotaxane.Because guanidyl can recognize different anions and has great application potential in biology and drugs, we designed a novel rotaxane with guanidyl in the guest part and phosphine group in host. So far, the synthesis of host successfully finished, and we’ve made great progress in the synthesis of guest.In summary, this dissertation has synthesized the rotaxanes based on phosphine oxide, dibenzylammonium, and urea functional groups, the switchable properties have been deeply carried on. After adding positive gelation factors to the rotaxane, some entative experiments of gelation application is firstly studied. Besides, we are trying to introduce guanidyl group into another rotaxane system. These are significant for further researches.