Study On Self-assembly Behavior Based On Pillar[5]arene

Self-assembly is a process of in which a disordered system of pre-existing building blocks spontaneously forms an organized system with unique structure and function without human intervention.Supramolecular chemistry can provide new concepts,methods and design ideas for the synthesis and preparation of building blocks and inject fresh blood into the self-assembly system.Host-guest interaction has been widely studied because of its reversibility and adaptability,as well as the properties of spatial matching and charge complementarity of the macrocyclic hosts with related guests.At the same time,the supramolecular self-assembly system based on macrocyclic molecules also attract many supramolecular chemists due to its unique charm in many fields,especially in the fields of biomedicine and material science.The new generation of macrocyclic pillararenes have unique advantages in supramolecular self-assembly due to their symmetrical rigid columnar structure,electron rich cavity,easy synthesis and functionalization.Moreover,due to the unique cavity structure of pillararenes,they have the rich host-guest chemical properties and they can complex with different types of guest,so they can form different interpenetrating structures.The advantage of the kind of interpenetrating structure is that it can connect functional groups to the assembly unit through host-guest interaction,avoid cumbersome organic synthesis process,and can easily construct functional self-assembly.Therefore,it is of great significance to construct interpenetrating structure through pillararenes and then further form self-assembly system.This dissertation is mainly studies the formation of interpenetrating structure through pillararenes and then further constructs the supramolecular self-assembly system.The supramolecular self-assembly based on pillararenes is studied from the following two parts.In the first part of the work,we constructed the interpenetrating structure of[c2]daisy chain of macrocyclic amphiphilic molecule based on pillararenes,and further studied the self-assembly behavior of the interpenetrating structure in aqueous solution and the regulation of assembly behavior through external conditions.Firstly,a pillararenes-based macrocyclic amphiphile H1 was prepared.H1 can act as a single-chain amphiphile and self-assembled into micelles in water.By adjusting the p H value of the solution,it can be transformed into bola-type supramolecular amphiphilic molecules based on[c2]daisy chain,and the micelles can also be transformed into nano tablets.This process can also be reversible through the regulation of p H.This p H-induced transition between macrocyclic single chain amphiphile and[c2]daisy chain-based bola-type supramolecular amphiphiles based on pillararenes was first reported,providing a new strategy to design the structure and self-assembly property of macrocyclic amphiphiles.The corresponding p H-responsive self-assembly system provides a promising candidate for preparing advanced material with different functions,such as controlled release,drug delivery systems,and surface modification.In the second part,we constructed a[4]rotaxane structure based on pillararenes through metal coordination and host-guest interaction,and further formed supramolecular polymers throughπ-πinteraction self-assembly.Firstly,we designed and synthesized guest G which contains both metal coordination andπ-πinteraction sites.It interacts with pillararenes to form[2]pseudorotaxane structure through host-guest interaction.After adding Cu²⁺,it forms a mechanical interlocked[4]rotaxane structure through metal coordination.Further,it self-assembled to form linear supramolecular polymers driven byπ-πinteraction by adding pyrene.This method of constructing supramolecular polymers with mechanically interlocked pillararene[4]rotaxane structure through host-guest interaction and metal coordination provides a new idea for the formation of polymers.