play device of next generation. Much efforts have been devoted in searching for strongly fluorescent organic dyes which work as a light emitting source of an EL display device. Previously, it was reported the preparation of di- and triphenylpyridine derivatives

A series of 4, 7-Di (alkoxy-substituted) phenyl-1,2,5-thiadiazolo[3, 4-c]pyridines were prepared and their absorption and fluorescence spectre were obatined. These compounds showed a large stokes shift of 115-135 nm arid 6-aryl derivatives and 6-alkoxycarbonyl opes are strongly fluorescent in a solid state.