Studies On The Supermolecules Formed By Cucurbituril And Multisite-heterocyclic Guests

Supramolecular chemistry based on non-covalent (hydrogen bond, ion-diploe and vander waals) initiates a new frontier of chemistry research. Supramolecular chemistry is being thrived for decades since its naissance and gradually becomes an interdiscipline covering many subjects such as organic chemistry, inorganic chemistry, physical chemistry, biochemistry and material chemistry. Molecular recognition and self-assemble is the important content of the supramolecular chemistry study, which provides the possibility to design stimulus-response devices and imitate the life secret at molecule level.Cucurbituril is another important generation of supramolecular host after crown ether, cryptand, cyclodextrin and calixarene. The origin of cucurbituril is very early while its boom research period comes much late. Although Behrend and co-workers synthesized cucurbituril in1905for the first time, they can not gain the accurate molecular structure due to the limits of the poor measurement condition at that time. In1981, Mock and co-workers restudied the research work of Behrend, and determined the structure of cucurbituril by using X-ray diffraction. It is found that the cucurbituril structure resembles the pumpkin of Cucurbitaceae. Thus, the new compound was named as cucurbit[n]uril and abbreviated as CB[n](n=5,6,7,8,10). Because of the unique physical and chemical property, CB[n] has become a hot research in the field of supramolecular chemistry attracting many scientists all over the world.Chapter1of this dissertation summarized the development of cucurbituril and its derivative. Meanwhile, the research achievements and applications of cucurbituril family in molecular recognition, molecular device, molecular catalysis and self-assemble block were introduced in detail.The synthesis and purification of cucurbituril homologues is the fundamental content studied by scientists all the time. The second chapter of this thesis focuses on the purification of cucurbituril homologues. Meanwhile, CB[7] and CB[5] are separated through ionic liquid. It is proved that this new separating method is convenient and high efficient, which could be utilized in the massive purification of CB[5] and CB[7].In chapter3, a new Gemini cationic surfactant HBPB-8is designed and synthesized, which can be self-assembled into supramolecular vesicle triggered by its formation of pseudorotaxane with CB[6]. TEM and Cryo-TEM were used to characterize the formation of supramolecular vesicle. Furthermore, the model drug carboxyfluorescein was applied to study the stability of supramolecular vesicle as the carrier in the drug deliver system.A guest molecule DPDB containing three bind sites for cucurbituril was designed and synthesized in chapter4. The size of the aliphatic part at the two sides of DPDB is appropriate and can be recognized by CB[6]. The xylyl group at the middle of the guest can only thread into the cavity of CB[7] or CB[8]. When the middle part of DPDB is occupied by CB[7] or CB[8], the addition of more cucurbituril will result in the oscillation of CB[7] or CB[8].'H NMR, MS, UV-vis, IR and TG were applied to characterize the property of pseudorotaxanes self-assembled by DPDB and cucurbituril. It is marvelous that the pseudorotaxane complex DPDB@CB[7]@2CB[6] self-assembled by DPDB and CB[7]/CB[6] can form stable supramolecular vesicle in DMF-aqueous solution. TEM and Cryo-TEM were utilized to characterize the formation of supramolecular vesicle. The formation mechanism of supramolecular vesicle is discussed. Moreover, the model drug carboxyfluorescein was applied to study the stability of supramolecular vesicle as the drug carrier.In chapter5, a guest molecule DMHB consist of N-methyl morpholine was designed and synthesized. The detail recognition of DMHB by CB[n](n=5,6,7,8) was studied through'H NMR. It is found that the cavity of CB[5] is too small to bind DMHB. CB[6] interacts weakly with DMHB. CB[7] possessed lager cavity can form stable pseudorotaxane complex with DMHB. Furthermore, the whole guest molecule can be encapsulated in the cavity of CB[8], whose size is the largest in CB[n](n=5,6,7,8).