The Design, Synthesis And Cell Imaging Applications Of Several New Fluorescent Molecular Probes Based On Xanthene

Rhodamine and fluorescein as a typical representative of the xanthene dye because of its very favorable photophysical properties, it has been widely used in environmental science, food science, life science, pharmaceutical and other fields. On the existing basis of the laboratory, we designed and synthesized three fluorescence probes based on rhodamine B and fluorescein. The main research work is as follows:In the second chapter, we designed and synthesized a novel fluorescent probe RBDPA, by the condensation of Rhodamine B and di (pyridine-2-methyl) amine. In EtOH/HEPES (1:1, v/v,100 uM, pH 7.2) solution, it exhibits high selectively and selectivity toward Al3+ by Uv-vis spectroscopy, fluorescence spectroscopy and visually recognizable color change. The Job’s plot, 1H NMR titration and DFT calculation data suggested that the RBDPA formed a 1:1 complex with Al3+, the binding constants and the detection limits were Ka= 3.84 x 104 M"1 and 0.196 μM. Fluorescence microscopy and its toxicity experiments further demonstrate that RBDPA can be used as a fluorescent probe to detect Al3+ in human L-02 cell.In the third chapter, we designed a new "off-on" fluorescent probe RBTDA containing a thiodiacetamine moiety and two rhodamine moiety. RBTDA can selectively detect Cr3+in a methanol-HEPES buffer (3:1, v/v,0.5 mM, pH 7.25) solution and exhibits a highly sensitive and selective turn-on fluorescent response by Uv-vis spectroscopy, fluorescence spectroscopy. The binding analysis based on Job’s plot,*H NMR titration, DFT calculation and mass spectroscopic data suggested that the RBTDA formed a 1:1 complex with Cr3+. The binding association constant (Ka) was estimated to be 5.01 ×104 M-1, the detection limit was further determined to be 0.378 μM. The fluorescence microscopy and its toxicity experiments proved RBTDA have potential applications in vivo biological detection.In the fourth chapter, we designed and synthesized a new fluorescein derivative (FIPY), the Uv-vis spectroscopy, fluorescence spectroscopy experiments show that FIPY exhibit a high selectively and selectivity toward Cu2+ in DMSO/HEPES (3:1, v/v, 1mM, pH 7.2) solution. The binding association constant (Ka) of FIPY for Cu2+based on 1:1 stoichiometry was estimated to be 1.29×104 M-1, the detection limit was further determined to be 0.296 μM.