Synthesis Of A New Class Of Melon Rings And Study On Their Supramolecular Self-assembly Properties

Cucurbit[n]urils(Q[n]s or CB[n]s, n = 5 ~ 14) are a family of macrocyclic compounds self-assembled from an acid catalyzed condensation reaction of glycoluril and formaldehyde. These pumpkin-shaped containers have a characteristic rigid hydrophobic cavity accessible through two polar portals rimmed with carbonyl groups. In particular, their superior molecular recognition and coordination properties in aqueous medium have attracted much attention in supramolecular chemistry. Compared to crown ethers, cyclodextrins, and calixarenes, cucurbiturils have better selectivity, affinity and chemical stability with guest molecules in aqueous solution. As a result, A wide variety of supramolecular species such as molecular recognitions, supramolecular assemblies, fluorescent probes, and molecular machines incorporating Q[n]s as the host have been reported. However, one of the challenges that needed to be addressed in the development of Q[n] chemistry is overcoming their low solubility in water, and Q[n] only soluble in strong acid such as formic acid, acetic acid, hydrochloric acid, and insoluble in organic solvents. On the basis of literature review, this thesis intends to design and synthesis of a new type of Hemicucurbit[n]urils by reaction of bureide and paraformaldehyde. Experimental results showed that we successful synthesis and separation of hemi-dimers based glycosides from hydantoin, although mass spectrometry showed hemicucurbit[n]urils were formed, pure products was not obtained. On the other hand, combined with the latest results in the synthesis of new functional cucurbiturils in our Lab, we synthesized a new type of ethylene derivatives derived guests, and analyzing their supramolecualr assemblies with such cucurbiturils. In particular, the photophysical property of such host-guest interaction derived has been detailed investigated.Contents of this thesis were completed as following:(1) Synthesis of new hemicucurbit[n]urils. Reaction of hydantoin and paraformaldehyde with molar ratio of 1: 1 in different acids solution, such as 9M sulfuric acid, formic acid, acetic acid, trifluoroacetic acid, hydrochloric acid in one-pot reaction at different temperatures and different times. The resulting products were determined by NMR, MS and single crystal structure diffraction. Experimetal results suggested that hemicucurbit[n]urils was formed, but we did not get the pure sample. However, we successfully got the pure product of hemi-dimers based glycosides and its X-ray structure.(2) Synthesis of ethylene based fluorescent guests. 1,4-bis[2-(4-pyridyl)ethenyl]benzene derivatives. Reaction materials including brominated alkanes with different lengths, γ-picoline, and terephthalic aldehyde. Guests with various carbon chain lengths were finally obtained(7C, 8C, 9C, 10 C, 11 C, 12C).(3) Properties and mechanism of cucurbit[n]urils and ethylene derivatives based supramolecular assemblies.UV-vis absorption, fluorescence spectroscopy, and ITC analysis were used to study the properties and mechanism of the host-guest based supramolecular system including the complex types and general formation tendency. In particular, we pay attention to the photophysical properties changes of the fluorescent guest before and after complexing with Q[n]s by carefully analysis the UV-vis, fluorescence spectrum and ITC data. We believed that the results should benefit to the potential application of such host-guest interaction based supramolecular system in analysis research field.