Design, Synthesis, And Testing Of New Difluoroboron-Derivatized Fluorescent Molecule

Boron dipyrrins (BODIPYs) have received increasing interest in research areas such as cell image, chemosensors, ions detection, fluorescent switches and dye-sensitized solar cells owing to their advantageous photophysical properties such as photostability, long absorbtion and fluoreescence wavelength, and high fluorescence quantum yields. Furthermore, BODIPY dyes are amenable to modifications, which allow fine-tuning of properties by introduction of suitable substituents at appropriate positions of the dipyrrin framework.In this study, a new class of aza-BODIPY derivatives 7 were synthesized from N-substituted aniline and diethyl malonate via six-step reactions. At first, a series of novel chalcone analogues 4 were synthesized from the reaction of 3-acetyl-4-hydroxy-N-methyl/benzyl-2(1H)-quinolinone 3, which was prepared from N-substituted anilines and diethyl malonate, with appropriate aromatic aldehydes catalyzed by L-proline in the presence of triethylamine via Aldol-condensation. Then intermediates 5 and 6 were obtained from the chalcone analogues 4. Finally, the target compounds 7 were obtained from the reaction of 6 with Boron trifluoride diethyl ether(BF3-Et2O) in THF. The affecting factors of each steps and the synthetic conditions were discussed and optimized in the paper.The structures of the new compounds were characterized by MS and 1H NMR spectra. The ultraviolet absorption spectrum and fluorescence spectrum of some products of the compounds 4,6 and 7 were measured. The results indicated that the target compounds 7 possessed obvious superiority fluorescence properties than 4 and 6. Its maximum emission wavelength was over 710 nm, and we expected that this kind of novel BODIPY Derivatives may have wide application in some research areas in the future.