Synthesis And Luminescent Properties Of Quinazolinone Boron Difluoride Compounds

Fluorescent dyes are widely used in people's production and life.According to the properties of dyes,they can be used in various fields such as photodynamic therapy and fluorescent probes.Boron difluoride compounds have attracted much attention as one of the most common dyes.In this paper,we used quinazolinone-2-pyridine as the main ring structure,and synthesized quinazolinone-2-pyridine boron difluoride compound?BODIQPys?by two-step reaction,which become a new fluorescent dye.This paper mainly has the following contents:1)design and synthesis of 6-haloquinazolinone-2-pyridine boron difluoride compounds,and discuss the effect of halogen on the whole molecule.Strong emission with high fluorescence quantum yield both in solution?up to 0.99?and in solid state?up to 0.60?was achieved in these compounds.For the 6-halogenated BODIQPy system,the heavy atomic effects of bromine and iodine were inhibited in solution due to the relatively high negativity of carbonyl oxygen in BODIQPy system.In the solid-state,the asymmetric structure induced a unique dimeric structure,and efficient luminescence could also been observed.The formation of halogen bond between carbonyl oxygen and bromine or iodine regulated stacking mode and enhanced intermolecular interaction resulting in a decline of the fluorescence quantum yield.2)design and synthesis of 6-methoxyquinazolinone-2-pyridine?5'-halogenated?boron difluoride compound,and discuss the halogen effect in BODIQPy system with pyridine 5-position.The introduction of methoxy group at 6-position of BODIQPys,instead of weakening the fluorescence,enhanced the charge transfer property and caused the emission wavelength red-shifted.These quinazolinone-based BF₂complexes exhibited highly efficient green luminescence with very large Stokes Shift.The introduction of halogen atom at pyridine moiety of BODIQPys can tune the LUMO levels in regularity while their HOMO levels remain intact.