Synthesis And Properties Of Stimulus-responsive Luminescent Carborane Compounds

Aggregation-induced emission（AIE）materials have been widely studied in recent years,which have greatly expanded the application field of organic luminescent materials.The optical properties of these compounds are largely affected by the molecular packing in the solid/aggregated state,and are easily influenced by external physical and chemical stimuli.Therefore,AIE compounds are a class of stimuli-responsive materials with great potential.Tetraphenylethene（TPE）derivatives are the most studied AIE compounds.They are the star molecules in the field of AIE because of their simple synthesis and easy modification.Carborane chemistry is an active research area,and carborane derivatives have a wide range of applications in areas such as biomedicine,molecular imaging,high temperature resistant materials and luminescent materials,so the study of functional carborane compounds is of great significance.This thesis focuses on the carborane-tetraphenylethene hybrid systems,mainly reporting the synthesis of a series of bridged carborane-tetraphenylethene derivatives,the structural characterization,optical properties of the resulting compounds,the mechanofluorochromic and/or thermoflurochromic property of some compounds and the related mechanism and application potential.The thesis is divided into the following five chapters:Chapter 1 is the introduction,in which the types of stimuli-responsive materials and the emission mechanisms of aggregation-induced emission compounds are introduced,and the research status of carborane-containing AIE materials is summarized and classified,and the research significance and purpose of this thesis are proposed.In chapter 2,the mixed-substitution tetraphenylethene derivatives with fluorine atom and formyl group are synthesized.The composition and structure of the compounds are characterized by FT-IR,NMR,HRMS and single-crystal X-ray diffraction,and the absorption and emission properties of the compounds are studied.The AIE and mechanofluorochromic and thermofluorochromic properties of the compounds（including some composites）are also studied.Compared with the non-fluorinated analogs,it is found that the introduction of fluorine atom can improve the stimulus responsivity of the compounds.Meanwhile,these compounds are important starting materials for the work in the following two chapters.In chapter 3,three bridged carborane-tetraphenylethene compounds are synthesized and characterized.The absorption,AIE properties,solid state emission and the mechanofluorochromic property of the compounds are investigated.The results show that the quantum yields and the responsivity to mechanic force are significantly improved by introducing the carborane motif.In chapter 4,four tetraphenylethene derivatives containing chiral tert-butylsulfinyl group and the corresponding four chiral carborane-tetraphenylethene compounds are synthesized.The structures are characterized by spectroscopic methods.Their optical properties are investigated and the chiroptical properties are preliminarily studied by circular dichroism and circularly polarized luminescence spectroscopy.The quantum yields of the chiral carborane-TPE compounds are higher than the starting materials without carborane substituent,and the CPL emission dissymmetry factor of one example reaches 3.2×10^-3,indicating the research potential of this type of chiral carborane compounds.In chapter 5,the results of the whole thesis are summarized and the main conclusions are drawn.Meanwhile,some perspetives regarding the related systems are provided.