Films of polydiacetylene (PDA)-containing polyesters with metal salts of Zn, Eu and Gd were prepared. Ultraviolet–visible (UV–VIS)
absorption and photoluminescent (PL) spectra indicated that the presence of the metal salts induced a small shift of their maxima to
higher and lower energies, respectively. PDAs films with an ester group in allylic position to the conjugated system presented two
emission bands. The higher energy emission band was assigned to carbonyl emission and the lower energy emission band to self-trapped
excitons (STE).