Synthesis And Self-assem Bly Of Coumarin-Based Polycatenar Compounds,Three Types Of Bolaamphiphiles And Janus Macrocycle Compound

Liquid crystal(LC)is a mesophase between solid and liquid.It has not only the orderliness of crystal but also the fluidity of liquid.Because of this characteristic,liquid crystal system has self-healing,irritability and adaptability.Therefore,in recent years,the self-assembly and multifunctional properties of liquid crystalline molecules are one of the hot issues in the field of scientific research.A deep understanding of the properties of liquid crystal molecules not only provides a theoretical basis for the study of self-assembly of soft materials,but also lays a foundation for guiding the synthesis and the applications of new multifunctional materials.Three different types of liquid crystalline molecular systems(Polycatenar,Bolaamphiphile and Janus macrocycle)have been designed and synthesized in this thesis.Different nanostructures are realized by self-assembly of different types of molecules,and different functional units are introduced to realize the multifunctionalities of these liquid crystal molecules.These studies benefit for the development of novel multifunctional materials and novel molecular self-assembled principles.The first chapter is the literature review including the following aspects:firstly is the progress of coumarin-based LCs and gels;secondly is the progress of self-assembly of bolaamphiphiles,such bolaamphiphiles can self-assemble into different structures,including one-dimensional(1 D)lamellar,two-dimensional(2 D)honeycomb and three-dimensional(3 D)columnar and cubic structures;thirdly is the progress of azobenzene-based LCs and gels,fourthly is the progress of 1,2,3-triazole-based LCs and finally is the progress of shape-persistent macrocycles(SPMs),especially Janus SPMs.In Chapter 2,the synthesis,self-assembly,photodimerization and chemosensor properties of coumarin-based polycatenar LC compounds were investigated.Compounds C/10 can exhibit Colsqu/p4mm-Colrec/p2mm-Colhex/p6mm phase sequence upon elongation of the alkyl chain.The photodimerization in both LC and non-LC phases lead to the formation of absolutely hexagonal columnar LC phases.On the other hand,these compounds C/n can form organogel in different organic solvents.The morphologies of xerogel are 3D porous morphology in less polar solvents and uniform microbelts in strong polar solvents.Photodimerization in gel states led to the formation of more ordered 3D porous morphologies or spherical flowerlike morphologies.Subsequently,upon irradiation with 254 nm UV light,these gel morphologies recover to their original morphologies.Finally,the UV-Vis,fluorescence properties and ion recognition properties of C/n are also investigated.C/10 show high selectivity to Fe3+,however C/10 no longer show ion recognition ability after irradiated by 365 nm UV light.Therefore,the synthesized C/n in this chapter have potentials as photoresponsive materials,fluorescent materials as well as fluorescent probes.In Chapter 3,the synthesis,self-assembly and white-light emissive properties of two series of X-shaped oligothiophene-based bolaamphiphiles with two branched lateral chains were investigated.These compounds form single-wall triangular honeycomb phase(Colhex/p6mm)to single-wall square honeycomb phase(Colsqu/p4mm).These oligothiophene-based bolaamphiphiles could form organogels in different organic solvents.2TB/3 can form organogel only in mixed solvents of acetonitrile and water and the morphology of xerogel is belt morphology,4TB/4 can form organogel with 3D networks composed of entangled fibrous aggregates with partial helical structures in acetonitrile,whereas 4TB/8 can form organogel with rod-like morphologies in acetone.The different morphologies may be attributed to the length of lateral alkyl chain and rigid core.The most interesting is that the white emission of mixture of 2TB/8 and 4TB/8 in THF solution can be achieved by doping red emission rhodamine B.In Chapter 4,the synthesis,self-assembly and photoresponsive properties of two series of asymmetric azobenzene-based bolaamphiphiles were investigated.The phase sequence from double-wall triangular honeycomb phase(Colhex/p6mm)to double-wall square honeycomb phase(Colsqu//p4mm)was observed in such bolaamphiphiles upon elongation of the lateral alkyl chains.These LC phases exhibit reversible photoresponse properties.Moreover,Azo-1T/n could form organogel with different morphologies in different organic solvents.The SEM image of the xerogel of Azo-1T/16 formed in less polar solvents shows a nanoribbon structure,whereas shows a 3D network composed of nanofibers in strong polar solvents.The morphology of these organogels could be changed into chiral wrinkled structures with 365 nm UV irradiation.These morphologies could be recovered to their original morphologies with visible light irradiation.Chiral structure could also be obtained by chiral doping with amino acid.After doping with L-alanine,the morphology of the xerogel is nanobelts structure,and after doping with L-phenylalanine,the morphology of xerogel is helical nanotubes coexisting with the twisted ribbons and nanoribbons.In chapter 5,the synthesis and liquid-crystalline properties of 1,2,3-triazole-based bolaamphiphiles(TTB/n,TT1/n and TT2/n)with different types,lengths and number of lateral alkyl chains are investigated.A phase sequence ranging from double-wall triangular honeycomb phase,square honeycomb phase with more disordered wall structures to square honeycomb phase with less disordered wall structures is observed in such 1,2,3-triazole-based bolaamphiphiles by changing the type of chain,number change and length.In such a way the influence of the chain length,chain branching and chain number on the self-assembly behaviors of these triazole-based bolaamphiphiles are investigated,systematically.Therefore,based on the results of the third,fourth and fifth chapters,by introducing of different functional units into bolaamphiphiles,different applications such as in the fields of photoelectric materials,fluorescent materials,photoresponsive materials and fluorescent probes can be realized.In Chapter 6,the synthesis,self-assembly and chemosensor property of a Janus macrocycle(BDT)with four oligooxyethylene(EO)chains inside the macrocycle and four alkyl chains outside the macrocycle are investigated.BDT can form organogel with partial helical morphology in organic solvents and show high selectivity to Cu2+.This is the first example that shape-persistent macrocycles(SPMs)shows selectivity to Cu2+.The results indicate that such macrocycle has potentials in organic multifunctional materials.In Chapter 7,the synthetic procedures of the nine series of target compounds and the related spectral data are provided.