Design,Synthesis And Self-assembly Of Azobenzene,Diphenylsulfone Polycatenar,Cyclotriphosphazene Liquid Crystal Compounds

LC,which thermodynamically prevails between the crystalline state and isotropic liquid state,is a unique state of matter.Owing to its appearance between two condensed state of matter,the LC phase is often referred to as the mesophase,having the anisotropic properties of crystals and flow properties of ordinary liquids.As functional stimuli-responsive soft materials,LCs have applications in materials science,biomedical science and nanoscience,etc.Novel mesogens by combination of different conjugated units such as azobenzene,heterocycles into the skeletons of the classical liquid crystals have been reported in order to create advanced functional nanomaterials.The first chapter is about the design,synthesis,self-assembly,ion recognition and photoelectric properties of azobenzene polycatenar liquid crystal compounds.Herein,we report the facile synthesis of series of novel polycatenar LCs AC^m/n and AE^m/n with an azobenzene core and 1,2,3-triazole units at both sides via the CuAAC click reaction.The compound AC¹/14 with one tetradecoxy chain at each end displays smectic C phase,all the other hexacatenar compounds except ACb³/12 with 6 alkyl chains attached equally at each terminal display columnar mesophases.In the contact region between the SmC phase of compound AC¹/14 and hexagonal columnar phase of AC³/14,a reversed bicontinuous cubic phase was induced.The effect of various linkages X as well as the number and length of the terminal alkyl chains on the self-assembly behavior of these compounds were systematically investigated.These compounds can self-assemble into gels with different morphologies in different organic solvents,they can also act as chemosensors of Fe³⁺and sodium dithionite with high selectivity.These multi functional polycatenar dyes should have great potentials in optical electronic,biological as well as medical areas.The second chapter introduces the design and synthesis,molecular self-assembly and ion recognition based on diphenyl sulfone polycatenar liquid crystal compounds.We have synthesized liquid crystallinepolycatenar compounds FA³/n and FE³/n with an diphenylsulfone core and 1,2,3-triazole units at both sides via a amide group?X=CONH?and a carboxyl group?X=COO?.Among them,none of the amide compounds FA³/n is a liquid crystal,and carboxyl group?COO?contained compounds FE³/10 is not liquid crystal,but FE³/16 shows a hexagonal phase.It is possibly due to the amidegroup?CONH?which is more rigid and more polar than the carboxyl group?COO?,leading to the disappearance of the liquid crystal phase.The gel properties of compounds FE³/16 and FA³/16 were also studied,whereas short chain compounds failed to form organogels.These results indicate that the length of terminal alkyl chains influences the gelation properties.Metal recognizing property of triazole unit leads to these compounds acting as Fe³⁺fluorescence sensor.In Chapter 3,We aimed to synthesize liquid crystalline dendrimers that have a central cyclotriphosphazene ring.Therefore,we designed two synthetic routes,and tried eight reaction systems by adjusting the reaction time and temperature,the reaction solvent and the base needed for the reaction.Although we obtained all the intermediates,we did not succeed in synthesis the target products.We will summarize some of the experiences and experimental conditions in the experimental process.We hope that this will help future research.The fourth chapter is the experimental section including the synthesis scheme and detailed experimental steps and spectral data.