Abstract: Three compounds with the formulawere synthesized and their fluorescene spectrawere studied. The results indicate that they exhibit both intramolecular excimer and exciplex formation depending on the solvent polarity. In the solvents with high polarity,e.g. acetonitrile and methanol,the intramolecular exciplexes are more likely to undergo radiationless decay by dissociation and their fluorescence emission can not be observed. The blue-shifted fluorescence peaks are believed to be due to intramolecular excimer formation. The ability of intramolecular excimer formation can be arranged in the following decreasing order: Ⅱ>Ⅰ>Ⅲ.