Syntheses And Fluorescent Properties Of Benzothiazole Derivatives

Benzothiazole derivatives have good fluorescence properties due to their large range of π-conjugated systems. This thesis was put forward based on the summarization of the application of benzothiazole compounds in fluorescence material. A series of benzothiazole derivatives has been designed and synthesized in order to investigate in the regulation between molecular structure and fluorescence properties, and the potential application in near-infrared(NIR) fluorescen probes. The main context included:Firstly, compounds 1-6 were synthesized through changing the number and substitution position of benzothiazolyl groups. According to the F- responsing, solvatochromic effect, white fluorescence and solid fluorescence, the fluorescence of these benzothiazole derivatives with the adjacent hydroxyl groups were ascribed to the excites-state intramolecular proton transfer(ESIPT) mechanism. It was also found that the increase of number of benzothiazolyl groups would result in the red shift of solid state fluorscence.Then, compounds 7-9 were synthesized with the introduction of vinyl bond into the benzothiazole derivatives. According to the F- response, solvatochromic effect, white fluorescence and solid fluorescence, the NIR fluorescence of 7 and 8 was ascribed to intramolecular charge transfer(ICT) mechanism, whereas the NIR fluorescence of 9 was attributed to both ESIPT and ICT mechanisms.At last, compound 10, a near-infrared fluorescent probe for cysteine was gained by protecting the hydroxyl group of compound 8. It was found that compound 10 showed a selective, response toward cysteine in ethanol/water(1:1) solution, with the near-infrared fluorescence at 670 nm. The probe has been successfully applied into the fluorescence imaging in living cells.