The Design And Synthesis Of Functional Derivatives Of Two Kinds Of Macrocyclic Arenes For Property Study

The rapid development of supramolecular host-guest chemistry greatly depends on the research and development of macrocyclic chemistry,and the important part of the host-guest chemistry is to improve the design,synthesis and functional properties of novel macrocycles.Directed by the above background,we designed and synthesized three novel macrocyclic hosts,including permethylated pillar[5]lite(Me P[5]L),perethylated pillar[5]lite(Et P[5]L)and perethylated pillar[6]lite(Et P[6]L).Compared with the traditional pillar[5,6]arenes,the three macrocycles possessed less modification sites and had an unmodified phenylene subunit.In addition,we studied the host-guest properties of Me P[5]L and the selected guests including halogenated alkanes and nitrile molecules to determine their association constants and binding modes.Through the fully modified functionalization of the OHP[5]L,we successfully synthesized the water-soluble P[5]L,and further explored their host-guest interactions and binding modes with sulfonate guests.Finally,inspired by the methylated leaning tower[6]arene reported by our group,we designed and synthesized a double-modified tetraphenylethylene(TPE)-conjugated fluorescent macrocycle(TPE-LT6),and investigated its fluorescent properties in solvents and solid state.In the first part,we synthesized the fragment skeletons of the permethylated pillar[5]arene and perethylated pillar[5]arene,and then reacted with the intermediate of the methylated leaning tower[6]arene to synthesize Me P[5]L,Et P[5]L and Et P[6]L.Besides,the single crystals of Me P[5]L and Et P[5]L were also successfully cultivated.After that,we obtained the per-hydroxylated P[5]L(OHP[5]L)through demethylation reaction of the Me P[5]L,and calculated rotational free-energy comparison between unsubstituted phenylene subunit of OHP[5]L and a subunit of per-hydroxylated pillar[5]arene(OHP[5]A).Density functional theory(DFT)calculations revealed that P[5,6]Ls had self-adaptive cavities because of the existence of unmodified phenylene subunit.Using the Me P[5]L as host and the halogenated alkane and nitrile molecules as guests,the binding ability and binding modes of them were fully investigated by ~1H NMR experiments.The results showed that the association between the host and the alkyl chain guests is 1:1 binding mode,possessing strong host-guest interactions.Comparing the different association constants between the host and the selected guests,we found that the functional group and size of the guest played a significant role in the host-guest interaction.In the second part,on the basis of the OHP[5]L obtained in the first work,we synthesized a cationic water-soluble derivative of P[5]L(CWP[5]L)modified with eight perpyridyl groups and an anion water-soluble derivative of P[5]L(CP[5]L)bearing full carboxyl groups through a series of fully functional modifications,and cultivated the single crystal structure of perbromoethylated pillar[5]lite(Br P[5]L).Subsequently,five sulfonates with different alkyl chain lengths were selected as the guests,and the CWP[5]L was used as the host to investigate the host-guest properties and the structural characteristics of CWP[5]L in water.For comparison,we also synthesized a cationic water-soluble derivative of pillar[5]arene possessing ten perpyridyl groups(CWP[5]A).Then,we calculated the binding constants between the two hosts and the selected guests by ~1H NMR experiments.The results showed that the CWP[5]L had strong binding constants with sulfonate compounds,which were stronger than the CWP[5]A with the sulfonate guests.Moreover,with increase of the size of the guests,the binding efficiency was enhanced significantly,which confirmed that the presence of unmodified phenylene subunit of the self-adaptive cavity,enhancing the size-fit ability of the CWP5[L],and strengthening the host-guest interactions.In the third part,based on the methylated leaning tower[6]arene,we synthesized a double-modified tetraphenylethylene(TPE)-conjugated fluorescent leaning tower[6]arene(TPE-LT6).The fluorescence experiments exhibited that the fluorescent host had obvious aggregation-induced emission(AIE)properties and the certain dependence on solvent polarity.Meanwhile,the fluorescence quantum yield and fluorescence lifetime of the TPE-LT6 were also measured.We believe that the fluorescent macrocyclic host TPE-LT6 will possess a great potential to be applied as fluorescent functional materials.