| Inspired by the helical structures of various biological macromolecules widely existing in nature,the design and synthesis of artificial compounds with helical structures,that is,foldamer,is currently a very active research field.Over the past two decades,a large number of artificial helical foldamers were reported.Scientists hope to further understand the relationship between the structure and function of various types of macromolecules in living organisms by exploring the relationship between the structure and function of artificial helical foldamers.In recent years,more attention has been paid to designing and synthesizing helical foldamers with higher-order structures.We hope to advance the exploration of artificial helical and provide a universal strategy for the synthesis of high-order helical foldamers.Starting from 8-chloroquinoline triazole oligomers,this thesis provides a new strategy for designing and synthesizing quadruple helical foldamers.We found that the introduction of a weak hydrogen bond network into the oligomers favours the formation of high-order helical structures.On the one hand,the existence of hydrogen bonds is the key to introducing the oligomer to form a helical structure;on the other hand,the weak hydrogen bond system would make it easier to assemble into high-order helical structures.Our research found that introducing a triazole group as a link group into quinoline system is a good way.Due to the extreme electron deficiency of the triazole group,its C-H can serve as a weak hydrogen bond donor,and the triazole group is also an aromatic group,which can also increase the ?-? stacking effect.For these two points,triazole groups are better than amides for constructing higher-order helical structures.In our triazole oligomers,the quadruple structure was observed in crystal and solution,and it also breaks the limitation that the quadruple helical in amides could not exceed one turn. |
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