Synthesis and photophysical properties of oligoarylenes with a pyrrolo[2,3-d]pyrimidine core

The palladium-catalyzed Suzuki–Miyaura reaction of 2,4-dichloropyrrolo[2,3-d]pyrimidine with aryl boronic acids has been studied. Pd(OAc)2/dicyclohexyl(2-biphenyl)phosphine/K3PO4 was found to be an efficient catalyst system to prepare 4-aryl-2-chloro- and 2,4-diarylpyrrolo[2,3-d]pyrimidines. Novel non-linear molecules consisting of a pyrrolo[2,3-d]pyrimidine core and aryl branches have been elucidated as blue light-emitters with fluorescence quantum yields ranging from 4% to 67% in THF solution. The impact of an electron-withdrawing t-BuOCO group attached to the pyrrole ring of pyrrolopyrimidine derivatives on optical properties is discussed.