Synthesis and optical properties of new conjugated polymers composed of 1,3,4-thiadiazole and 2,5-dialkoxybenzene rings

Intramolecular cyclization of precursor polyhydrazides derived from hydrazi ne and four 2.5-dialkoxyterephthalic acids by dh ect polycondensation with Lawesson's reagent afforded new conjugated polymers constituted of 1,3,4-th iadiazole and 2,5-dialkoxybenzene units. The polymers emitted bluish green light in solution and green light in solid state in spite of the coexistenc e of non-cyclized hydrazide linkage in the backbones, the Stokes shifts bei ng 91-138 nm in the solid state. It was suggested that these polymers have appropriate lengths of conjugation backbones based on the 1,3,4-thiadiazole moiety.