The Synthesis And Properties Of Helicenes And Dyes Based On Benzothiadiazole

In recent years,benzothiadiazole,as an important organic small molecule skeleton,is often designed into organic molecules with different properties.At present,various types of benzothiadiazole derivatives have been developed and widely used in cell imaging,biosensing,solid materials and other fields.Double helicenes have attracted increasing attention of researchers for their unique structures as well as potential application in material science.Most of the double helicene compounds are all-carbon helicenes,and nitrogen-doped double helicenes are rarely synthesized and studied.As polycyclic aromatic hydrocarbons doped with heteroatoms could show specific optoelectronic properties,it is necessary to develop new strategy for the synthesis of double azahelicenes.In addition,More and more people pay attention to the application of benzothiadiazole fluorescent materials in various fields.Design and synthesis of multifunctional organic fluorescent emitters based on benzothiadiazole structure are still highly demanded and challenging.First,three double aza[5]helicene compounds have been designed and synthesized through Bischler-Napieralski cyclization.These molecules have symmetrical saddle-type conformations and PM configurations.Moreover,these molecules could exhibit positive solvatochromic properties and have large Stokes shifts in various organic solvents.The results calculated by DFT are consistent with the actual fluorescence properties of these molecules.This work provides a new strategy for the synthesis of double aza[5]helicene molecules with fluorescent properties.In the second part,we designed and synthesized 6 kinds of imidazole-benzothiadiazole-structured organic fluorescent molecules.Significant changes in the fluorescence emission of these compounds in acid-base indicate that these molecules can be used in anti-counterfeiting inks.Moreover,compound 3f with methyl group can be used for potential fingerprint development.High-contrast fingerprint images are obtained on various substrate surfaces.Compound 3d with hydroxyl phenyl group can be utilized for lysosomes imaging in living cells accurately with high efficiency.This work provides a series of imidazobenzothiadiazole-based multifunctional organic materials with potential applications in security inks,latent fingerprint imaging and lysosome staining.