Regulation Of Fluorescenct Behaviors Of Coumarin Derivatives In Solid/Liquid States

As a class of traditional fluorescent dyes,coumarin has been widely used in organic electroluminescent devices,fluorescers,laser dyes,medical science and other fields.Generally coumarin dyes show high fluorescence quantum yields in dilute solutions,but exhibit fluorescence quenching in both aggregated and solid states.To address this problem,in this dissertation,utilization of the synergistic effect of intramolecular charge transfer and the molecular packing patterns in crystal via introduction of alkyl or aromatic groups at different positions on the coumarin skeleton.The new developed coumarin derivatives exhibit high fluorescence quantum yields both in solution and solid states.The detailed research results are as following:1.Different alkoxy groups were introduced at the 7-position of coumarin,including methoxyl substitutent?CM1?,ethoxyl substitution?CM2?,butoxyl substitutent?CM3?,and hexoxyl substitutent?CM4?,iso-octyloxy-substitutent?CM5?and dodecyloxy-substitutent?CM6?coumarin derivatives.All their photophysical properties in solution,aggregation,and solid state were researched.Combined with theoretical calculations and single crystal data,it was found that the introduced alkoxyl substituents not only enhanced the ICT effect,but also modified their molcecular packing patterns in the crystals,thus giving high luminescence efficiency both in solution and the solid sate simultaneously.2.Two compounds with hexyloxy substitutent at their 7-position,but differening at the 3-position with 1-naphthalenyl?CM7?and 2-naphthalenyl?CM8?were synthesized,repectively.All their photophysical properties in solution,aggregation,and solid state have been researched.Combined with theoretical calculations and single crystal data,it was found that CM8 not only exhibits enhanced ICT effect,but also elimenated adverse intermolecular interacions in its crystal,which make CM8 giving higher luminescence efficiency in solution and the solid sate than those of CM7.3.Two compounds with diethylamine substitutent at their 7-position,but differening at the 3-position with benzyl?CM9?and thiophenyl?CM10?were synthesized,respectively.Studies revealvedtheir fluorescent behaviors can be tuned by boron trifluoride?BF₃?and trimethylamine?TEA?.The fluorescence intensity decreases after BF₃ was added to CM9 in solution or filter paper,while the fluorescence intensity increased for CM10 in the same case.After adding TEA,their fluorescence returned to the original state,respectively.With the substituent effect,the stimuli response“fluorescence quenching”and“fluorescence on”can be controlled successfully.