Study On The Synthesis Of Rotaxane And Catenane Based On Pillar[5]Arenes

Rotaxanes and catenanes as fundamental mechanically interlocking molecules（MIMs）have become one of the hottest research areas due to their inherent self-assembly properties and various potential applications.The synthetic isolation of new rotaxane and catenane compounds is critical for their successful application in the fabrication of molecular machines,sensors and nanomaterials.In this paper,several rotaxanes and catenanes with pillar[5]arene as the basic skeleton were designed and synthesized.The main contents are as follows:1.A series of monosubstituted amide-based pillar[5]arenes were synthesized by amidation of monoesterified pillar[5]arenes with alkyldiamines,which can form pseudo[1]rotaxanes through self-assembly.The pseudo[1]rotaxanes were capped with 3,5-ditert-butylsalicylaldehyde and 5-bromosalicylaldehyde to obtain Schiff bases[1]rotaxanes.The recognition of Schiff bases[1]rotaxanes with 9 metal cations such as Cd2+,Co2+,Cu2+，Zn2+was studied by fluorescence spectrofluorimetry.The results show that the Schiff bases[1]rotaxane can specifically recognize Zn2+,which can significantly enhance the fluorescence of[1]rotaxane,and the complexation ratio is 2:1.2.A series of bipillar[5]arenes compounds were synthesized by amidation reaction between azobenzene-based carboxylic acid derivatives and monoaminoalkyl-functionalizedpillar[5]arenes.Experiments show that longer alkyl chains are more favorable for the formation of rotaxanes.When the carbon chain length of alkyldiamines is long enough,bipillar[5]arenes can self-assemble to form bis[1]rotaxane structures.When the chain length is short,the alkyl chain moiety exists in free form and cannot form bis[1]rotaxane.Under 365 nm UV light irradiation,the azobenzene unit can realize the transformation from trans configuration to cis configuration,confirming the photo-regulated cis/trans isomerization performance of this bis[1]rotaxane.3.[1]Rotaxane and[1]/[2]complex rotaxane were synthesized by self-piercing-endcapping method.The self-penetrating pseudo[1]rotaxane containing triazole units was synthesized by amidation reaction and "click" reaction,and the pseudo[1]rotaxane was capped to obtain[1]rotaxane.Using the host-guest complexation between triazole and pillar[5]arene,an ethoxy pillar[5]arene was complexed on the pseudo[1]rotaxane branched chain and then capped to obtain[1]/[2]complex rotaxane.4.Mechanically self-locking pseudo[1]catenane compounds were synthesized by amidation of dicarboxylic acid-functionalized pillar[5]arenes with alkyldiamines,and a small amount of gemini catenane compounds were also obtained.A linear molecule containing a benzene unit was used to react with a dicarboxylic acid pillar[5]arene to obtain a single pillar[5]arene compound with a branched chain that did not penetrate into the pillar[5]arene cavity.