Red emitting diphenylpyrrolopyrrole (DPP)-based polymers prepared by Stille and Heck coupling

Six new soluble conjugated polymers are described, which were prepared by Stille and Heck polycondensation reactions. They alternately consist of dialkylated 1,4-diketo-3,6-diphenyl-pyrrolo[3,4-c]pyrrole (DPP) units and divinylbenzene or thiophene-based units. The polymers were prepared from 1,4-diketo-2,5-dialkyl-3,6-di(4-bromophenyl)-pyrrolo[3,4-c]pyrrole with alkyl being hexyl (1a), methyl (1b), and 2-ethylhexyl (1c) and 2, 5-bis(tributylstannyl)thiophene (2), 5,5'-bis(tributylstannyl)bithiophene (3), 3,4-ethylenedioxythiophene (4) and divinylbenzene (5). The new polymers exhibit brilliant red purple color and strong photoluminescence in common organic solvents. The DPP-phenylenevinylene copolymers exhibit molecular weights up to 41000 Da, and the poly(DPP-thienylene)s up to 12200 Da. In chloroform, the poly(DPP-thienylene)s exhibit absorption and photoluminescence maxima up to 560 and 624 nm, respectively, the corresponding maxima of the poly(DPP- phenylenevinylene)s are at 529 and 640 nm, respectively. Quantum yields of fluorescence up to 36% were determined. Cyclic voltammetric studies indicate quasi-reversible oxidation (p-doping) of the poly(DPP- thienylene)s and irreversible reduction (n-doping) of all polymers.