Synthesis And Properties Of Pillararenes-based [1] Rotaxane

Pseudorotaxane and rotaxane are the most basic structures of mechanically interlocked molecules(MIMs).Some major macrocyclic compounds such as crown ether,cyclodextrin and calixarenes have been successfully employed in the construction and functional applications of rotaxanes.In recent years,many researchers found that pillararene has a unique tubular cavity structure and good combining ability with guest molecules,and a series of rotaxanes with diverse supramolecular structures were synthesized by self-assembly strategy.Pillararene-based supramolecules were widely used in the construction of molecular shuttles,switches and probes.In this paper,we have synthesized a series of pseudo[1]rotaxane and[1]rotaxane based on mono-functionalized pillar[5]arenes,and studied their response to external environmental stimulus.The main achievements are as follows:1.We have successfully synthesized thirteen pillar[5]arene Schiff base derivatives by the reaction of functionalized pillar[5]arenes mono-hydrazides and mono-amides with 2-,3-,or 4-pyridinecarboxaldehyde.It was found that some pillar[5]arene Schiff bases could form pseudo[1]rotaxanes in the liquid and solid state through the self-inclusion pattern.The pseudo[1]rotaxane could convert to free form or by changing the polarity of the solvent and the external temperature.All compounds were characterized with NMR,IR,HRMS spectra.Six single crystal structures were determined by X-ray diffraction.2.We have synthesized series of amide bonding bridged bis-pillar[5]arenes by two synthetic methods.The first method was HOBT/EDC1 catalyzed condensation of pillar[5]arene mono-oxyacetic acid with diaminoalkanes.The second method was the amidation reaction with pillar[5]arene mono-amides with diacyl chloride.It is interesting to find that bis-pillar[5]arenes with longer amido-bridged chain can be self-locked to form a unique bis-[1]rotaxanes in solution and in solid states.All the bis-pillar[5]arenes were characterized with NMR,IR,HRMS spectra.Three single crystal structures were determined by X-ray diffraction.3.We have synthesized series of bis-pillar[5]arenes Schiff bases and thioureas bridging chains by the reaction of functionalized pillar[5]arenes mono-hydrazides and mono-amides with several dialdehyds,1,4-phenylenediisothiocyanate and 1,6-hexylenediisocyanate.Besides charactization their structures by NMR,IR,HRMS spectra,one single crystal structure with bis-[1]roataxane were successfully determined.The recognition ability of these functionalized bis-pillar[5]arene derivatives to transition metal cations was studied by UV spectroscopy.