Supramolecular Polymers Based On The Orthogonal Self-assembly Of Quadruple Hydrogen Bonding And Host-guest Recognition

Supramolecular polymers, which are aggregate arrays based on small molecular weight monomeric units brought together by reversible and highly directional non-covalent interactions, have attracted increasing attention in recent years. They not only possess many of the properties of traditional polymers, but also possess unprecedented distinct new material properties due to their dynamic reversible characteristics, which ensure their potential application in a broad range of fields. Among the non-covalent interactions, the highly directional multiple hydrogen bonding units ureidopyrimidinone (UPy) was one of the mostly used units in supramolecular polymer construction due to its high association constant (Kass>107M-1in chloroform) and synthetic accessibility, which can ensure real macroscopic polymeric properties. In this thesis, we utilize the ureidopyrimidinone (UPy) as the basic building blocks and/or with the combination of host-guest recognition units to construct new kinds of supramolecular polymers, and it consists of four parts of research work as follows:Part1. A novel, bifunctional quadruple hydrogen-bonding ureidopyrimidinone (UPy) unit bridged by photochromic dithienylethene (1) has been synthesized, which affords linear assemblies in solution and undergoes concentration-dependent ring-opening polymerization. The two UPy functional groups of1can dimerize intramolecularly to form a cyclic monomer with the two thienyl rings fixed in a parallel conformation, which prohibits its photocyclization. We exploited the photochemical reactivity and resonance difference of the linker of the bis-UPy derivative as well as using the more typical1H NMR, DOSY, and Ubbelohde viscometry methods to investigate for the first time the ring-chain polymerization mechanism. Moreover, we fabricated a mixed polymer film with a fluorescent dye noncovalently endcapping the linear photochromic assemblies through quadruple hydrogen bonds, which showed nondestructive fluorescent read-out ability for data storage by fluorescence resonance energy transfer (FRET) from the fluorescent dye to the closed form of the diarylethene.Part2. A novel linear supramolecular polymers, have been constructed at "high" concentrations from two heteroditopic monomers:M1, which bears one paraquat moiety and one UPy unit; N1, which bears one crown ether moiety and one UPy unit, both at the two ends of a hexyl linkage. It was based on the orthogonal self-assembly of the quadruple hydrogen bonding ureidopyrimidinone and crown ether-paraquat host-guest recognition motifs, with both of these two kinds of non-covalent interactions in the main chain.Part3. The creation of novel crown ether-paraquat polypseudorotaxane networks, constructed by bisparaquat monomers threading into the cavity of the crown ether units of linear supramolecular polymers that are formed based on the quadruple hydrogen bonded unit (UPy) in the concentrated solution, is described. The reversible and tunable supramolecular polymer backbones would potentially bring unique, applicable properties to these traditional polypseudorotaxane structures.Part4. We have designed and synthesized two kinds of rigid bis-urea macrocycles linked by photochromic building blocks dithienylethene, and also exploited their photochromic properties under the UV/Vis irradiation. This two bis-urea macrocycles might be used in molecule recognition, and the construction of new rotaxanes and catenanes.