Synthesis And Spectral Properties Of BF₂-multipyrromethenes

Boron-dipyrromethene (BODIPY) dyes as important organic dyes, have outstanding physical and chemical properties:high fluorescent quantum yields (Φf) and high molar extinction coefficients (ε), good stability to light, low susceptibility to solvent polarity and pH, narrow emission band, maxium absorption and emission wavelength in visible region, easy functionalization and modification, and have found wide applications in a diverse research fields as labeling reagents, fluorescent molecular probes, fluorescent molecular switches, chemsensors, anti-cancer drugs, photosensitizers, solar cells, energy transfer cassettes and so on.This thesis mainly focuses on the modification of the BODIPY skeleton, from which a series of novel fluorescent dyes have been synthesized, their optical properties and singlet oxygen generation properties have also been investigated as summarized in the following:1. Electrophilic bromination of pyrrolic-unsubstituted BODIPY with bromine, from which the regioselectively brominated BODIPYs2-3,2-5were generated in high yields. These resultant bromoBODIPYs were further applied to the regio selective substitution reaction to generate a series of functional BODIPYs in high yields. We found that the nucleophilic substitution of the brominoBODIPYs first took place at3,5-positions. The spectroscopic properties of these resultant BODIPYs have also been studied.2. A simple synthetic route has developed for the generation of a set of prodiginines with both the symmetrical and unsymmetrical pyrrolylpyrromethene frameworks in high yields.3. Based on the ready-made a-formylBODIPY platform, a set of meso-a directly linked bisBODIPYs have been synthesized and characterized via NMR and X-ray diffraction. The spectroscopic properties and their singlet oxygen generation efficiencies in different solvents have also been investigated. Both their singlet oxygen generation efficiencies and the fluorescent quantum yields are solvent-dependent (higher in nonpolar solvents with respect to those of polar ones). The further application of these dyes to Knoevenagel condensation has provided a set of Near-IR BODIPYs.