Design, Synthesis And Application Of BODIPY-based Fluorescent Aluminium Ion Sensor And ESIPT-based Organic Fluorescent Dyes

Among the numerous fluorescent dyes, BODIPY(4,4-difluoro-4-bora-3a,4 a-diaza-s-indacene) fluorescent dyes are endowed with excellent photophysical properties, for instance, high molar extinction coefficient, sharp fluorescence peak, exceptional insensitivity to the polarity of solvents as well as pH. In recent years, BODIPY fluorescent dyes have acted as good candidates for optical devices, biolabeling and sensors. Thus, utilizing BODIPY as fluorophore and Schiff base as functional group, we designed and synthesized a highly selective turn-on fluorescent chemosensor(PSI-BDP) for Al3+. Its properties was characterized by 1H NMR, 13 C NMR and HRMS, and the response to aluminium ion was measured simultaneously. Upon addition of aluminium ions, the PET process was switched off by coordination of Al3+, and the cassette PSI-BDP underwent through-bond energy transfer(TBET) to release strong fluorescence.ESIPT(Excited-state Intramolecular Proton Transfer)-based organic molecules possess unique photophysics properties(large Stokes shift, double emissions, fast proton transfer, four-energy lever light cycle process). In addition, owing to the sensitivity to surrounding environments, ESIPT-based organic molecules have been widely used in fluorescent chemosensors(ion sensors, pH sensors, viscosity sensors and so on), which became a hotspot of research fields in chemosensors. In the thesis, via the mechanism of blocking ESIPT process and then restoring ESIPT process, two new 3-hydroxyflavone fluorescenst probes MHF-1 and MHF-2 integrated with ortho-azidepheyl acety unit and 3-hydroxy acetyl disulfide were rationally designed and synthesized. Probe MHF-1 was highly selective and sensitive sensing of triphenylphosphine, and probe MHF-3 was highly selective and sensitive sensing of cysteine. Upon addition of target detection objects triphenylphosphine and cysteine, the fluorescence of probe MHF-1 and MHF-3 released immediately recovering the dual emissions associated with N*–T* tautomerism, accompanied by the solutions from almost no fluorescence to yellow-green fluorescence. Moreover, we successfully designed and synthesized a highly selective ratiometric 2-(2’-Hydroxy-phenyl)benzothiazole-based fluorescent chemosensor HBT-1 for sulfite ions. When probe HBT-1 reacted with sulfite ions in the acetonitrile/water(1/1, v/v) mixed solution, fluorescence peak blue-shifted from 660 nm to 492 nm, with the solution from red fluorescence to blue-green fluorescence.