New deeply coloured and fluorescent polymers with 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole units in the main chain

New deeply coloured and fluorescent copolyesters and -urethanes with 1,4-di oxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) units in the main chain were pr epared. The chromophoric units are incorporated in the backbone via their N -alkylated lactam groups. The DPP-containing monomer 1,4-dioxo-2,5-bis(6-hy droxyhexyl)-3,6-diphenylpyrrolo[3,4-c]pyrrole (2) was obtained by N-alkylat ion of 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (1) with 6-chlorohexanol . Copolyesters were prepared by (a) solution polycondensation of mixtures o f 2 and 1,12-dodecanediol with terephthaloyl chloride and (b) melt polycond ensation of the diol mixture with dimethyl terephthalate using tetrabutoxyt itanium as catalyst. Copolyurethanes were prepared by polyaddition of mixtu res of 2 and 1,12-dodecanediol with hexamethylene diisocyanate. The copoly eaters are readily soluble in common organic solvents, while the copolyuret hanes are only soluble in rather exotic solvents such as p-cresol. Polymer solutions are yellow to orange with optical absorption maximum at 470 nm an d fluorescence maximum at 520 nm. the Stokes-shift bring about 50 nm. All c opolymers are partially crystalline, the crystallinity decreasing with incr easing DPP content. Possible origins for the influence of the DPP content o n the crystallinity of the polymers are discussed. The thermal stability of the copolyesters is independent of the DPP content, the decomposition temp erature being about 646 K. The limit of thermal stability of the copolyuret hanes is about 600 K and increases slightly with DPP content.