Four 2-arylbenzothiazole compounds have been synthesised.All the compounds show fluorescence. From the fluorescence excitation spectra of compounds of Ⅰ、Ⅱ、Ⅲ and Ⅳ

it is seen that each spectrum has three excitation bands

two shorter wavelength excitation peaks are always at 310 urn and 360 nm respectively; nother longest excitation band is located at different positions for different compounds. The longest excitation bands and emission spectra of compounds Ⅱ

Ⅲ and Ⅳ occur red shift in comparison with the longest excitation band and emission spectrum of Ⅰ because of the interaction between donor and acceptor in compounds Ⅱ and Ⅲ or the enhancement of conjugated degree in Ⅳ.