Syntheses And Application Of Selenium-Containing Pillar[n]arenes

The design and synthesis of new macrocyclic host molecules represent challenging areas of supramolecular chemistry.In 2008,Ogoshi et al.reported a new class of pillar-shaped macrocyclic hosts,known as "pillar[n]arenes".Pillar[n]arenes became a new generation after crown ethers,cyclodextrins,calixarenes and cucurbiturils.Till now,pillar[n]arenes are recognized as key players in supramolecular chemistry because of their facile synthesis,unique pillar shape,versatile functionality and interesting host-guest properties.Based on the versatile functionality,in this thesis,we investigated the preparation of selenium-containing pillar[n]arenes,their redox-responsive complexation with different guests and self-assembly in water based on the new molecular recognition motifs.The main content of the dissertation includes four parts as following:In the first part,we synthesized a selenium-containing bola-type macrocyclic amphiphile and investigated its controlled release of small molecules with DOX as the model compound.Selenium-contianing pillar[5]arene was characterized by 1H NMR spectroscopy,77Se NMR spectroscopy,13C NMR spectroscopy and mass spectrometry.It self-assembled in water to form vesicles with redox responsiveness.The selenoxide moieties can be reduced to the hydrophobic selenide groups in the presence of VC,thus turning amphiphilic pillar[5]arene into water-insoluble pillar[5]arene and con'verting the vesicular structures into irregular assemblies.More intriguingly,the vesicles were recovered upon addition of H2O2,implying a reversible self-assembly process.Furthermore,we applied these redox responsive pillar[5]arene vesicles in the controlled release of doxorubicin(DOX)molecules.In the second part,we constructed a redox-responsive supramolecular amphiphile between a selenium-containing pillar[5]arene and a pyridinium bromide derivative,which could self-assemble into vesicles in aqueous solution.The supramolecular vesicles also showed reversible redox-responsiveness,that is,vesicles could be destroyed by adding VC and recovered upon addition of H2O2.Furthermore,these redox-responsive vesicles were used in the controlled release of DOX-HCl.In the third part,we investigated a novel dual-redox responsive molecular recognition motif between selenium-containing pillar[6]arene and ferrocenium cation guest salt.The selenium-containing pillar[6]arene was characterized by 1H NMR spectroscopy,77Se NMR spectroscopy,13C NMR spectroscopy and mass spectrometry.Based on this dual redox-responsive host-guest recognition motif,a selenium-containing supramolecular amphiphile was further fabricated,which could self-assemble into vesicles in aqueous solution.This dual redox-responsive supramolecular system may have a potential in the construction of functional architectures with many promising application,such as molecular logic gate.In the last part,we designed and synthesized a selenium-bridged A-A type pillar[5]arene dimer having two recognition sites and a symmetric B-B type guest possessing two cyano sites and triazole sites at its ends to form a linear supramolecular polymer.Through 1H NMR,DOSY and specific viscosity,we found that the formation of the supramolecular polymer was mainly dependent on the monomer concentration.The supramolecular polymer could be disrupted by?-radiation or adding peroxides or GSH due to the damage of a diselenide group in the pillararene dimer,which may have potential to fabricate supramolecular materials with more complex structures and functions.