Synthesis, characterization, and properties of 7,7′-bis(3,6-di-tert-butylcarbazol-N-yl)-substituted fluorenyl-oligothiophenes

A series of new 7,7′bis(3,6-di-tert-butylcarbazol-N-yl)-substituted fluorenyl-oligothiophenes bearing 0-, 2-, 4-, 6-, and 8-thiophene rings, namely BCFTn, were synthesized using palladium catalyzed Stille dimerization coupling reactions of their corresponding brominated thiophenes. The relationship between the chemical structure and the properties of these oligomers was evaluated. With respect to the electronic properties, the longest wavelength absorptions, emissions, and also the oxidation potentials can be tuned by varying the conjugation length of the oligothiophene segments. The terminal carbazole and fluorene moieties of the resulting materials are beneficial for their morphology, conjugation length, and solubility.