| Helical structure is the core structure of biological research and also exists in nature.For example,the winding direction of morning glory,the threads of conch et al are all helical,as well as DNA which is the basis of most life also presents double helix structure.Inspired by the helical structure of these organisms,and the huge potential application of them,people have developed a variety of advanced structures through reasonable design.Such as the development of aliphatic helical,aliphatic –aromatic and the study of aromatic helical structures in recent years.The study of aromatic helical structures is currently mostly focused on oligomers due to their rigid main chain and poor solubility et al.As having learned the folding mechanism of various helical structures based on the diversification of molecular structure,the development of supramolecular chemistry and the continuous improvement of chemical characterization,we would like to challenge the synthesis and study of novel aromatic helical polymers and supramolecular polymers by using covalent bond,dynamic covalent bond and metal coordination of supramolecular force.The specific work is as follows:1.The construction of helical polymer based on the covalent bond and generation of white light by adjusting the single and double helix to appropriate proportion.Moreover,an ion channel of single molecular is achieved by use of its hollow hole.As the covalent aromatic helical polymer could only be synthesized in monotonous manner with repeating units connected one by one,and the more the accumulation of the rigid aromatic ring structure is,the more poor the solubility of the formed polymer is.Therefore,getting an aromatic helical polymer with high degree is still a challenge.By using the dihydrazide and diacid chloride of terphenyl,we would poduce a helical polymer connected through covalent bond with high molecular weight and study its properties.There are two reasons why we choose terphenyl as the main chain structure.Firstly,when oxadiazole was introduced after completion of the reaction,the main chain could form an angle as the energy of oxadiazole and terphenyl reaching the most stable state,which making the polymer bent to form a helical structure.Secondly,the hole of the structure must be controlled in appropriate size to prepare for construction of single molecule ion channels and realization of ion selectivity.There are single and double helices in the polymer solution.By adjusting concentration and temperature,the two kinds of helices can be controlled to an appropriate ratio to achieve white light.It has been proved that the emission of white light is originated from the combination of blue light emitted by single helices and yellow light emitted by double helices with appropriate proportion,which provides a new pattern for the emission of single organic white light.On the other hand,we have succeeded in obtaining ion channels with hollow channels of aromatic helices with appropriate length.As the stable helices can cross the lipid bilayer,so it has a high transmission efficiency for protons and cations.Moreover,the single-molecule helical channel can even be comparable with the natural protein channel,which realized the simulation of natural channel and laid the foundation for transport in single-molecule level.2.The construction of helical structure based on the spontaneous selectivity of reversible dynamic covalent bond and the study of amplification of its chirality.More over,the absolute control of conformation for helical polymer was achieved by the steric hindrance effect and special microenvironment was realized by using the difference of the holes inside outside to achieve the catalytic oxidation of thiophenol.In this part of the study,two main works have been done.First,C-type building block with most stable conformationis is designed,by using its own radian and the intramolecular hydrogen bond formed after reacting with the quinoline molecule,we could get a helical structure.When mixing the chiral and achiral derivative of quinoline with C-type molecules involving hydrazide at both ends,we found that a phenomenon of chiral amplification was existing by measuring the proportion of the system,which laid the foundation for the future development of dynamic functional materials and asymmetric catalysts.Based on the realization of helical structure with dynamic covalent bond,diacyl hydrazide and dialdehyde were used to form aromatic helical polymer.By using the strong steric hindrance,self-folding helical polymer controlled by trans-conformation was synthesized thus achieving the absolute control of the conformation.And the hollow tubular structure produced by the helical folder was used as the microenvironment to catalyze the oxidation reaction of thiophenol in the presence of hydrogen peroxide.3.Construction of Highly Efficient Artificial Mimetic Enzymes Based on Supramolecular Polymers.With the development of supramolecular chemistry,the classical metal-organic self-assembly system has become an ideal tool for building advanced structures.Moreover,the incorporation of metal coordination with supramolecular polymer is attracting more and more attention due to the combination of the function owned by organic polymer and magnetic,electronic,optical and catalytic properties of metal.In this part,we connect the metal-organic system formed by amide bond with both ends of hexamethylene diamine,as long as Cu1 + or Zn2 + is added to the system,the two single-stranded molecules can be coordinated with metal ions to form a double helix as linker to get supramolecular polymers.Considering the two ends of the double helix is coordinated by Zn2+,it is desighed as metal hydrolase and has successfully catalyze the hydrolysis of PNPA.However,the supramolecular polymer metallohydrolytic enzyme model formed by double helix molecules as linker,possessing a high catalytic activity,which achieves 23 times the catalytic efficiency of the double helix due to the proximity of the adjacent catalytic sites in space and increased collision probability with substrate. |
PDF Full Text Request