Synthesis, Characterization, and OFET and OLED Properties of π-Extended Ladder-Type Heteroacenes Based on Indolodibenzothiophene

Ladder-type heteroacenes based on indolodibenzothiophene have been synthesized. The route involved a regioselective twofold intramolecular acid-induced cyclization of the central bis(butylsulfinyl)phenyl unit onto the adjacent carbazole units, followed by dealkylation to give diindolobenzobisbenzothiophene (DIBBBT) derivatives. Importantly, this sequence proceeded efficiently in the presence of the chloro substituents which provided reactive sites for further π-extension of the DIBBBT core. The chloro derivative underwent twofold palladium-catalyzed Suzuki–Miyaura reactions with phenylboronic acid or 4-n-octylphenylboronic acid. Compounds have been characterized by 1H NMR spectroscopy, mass spectrometry, elemental analysis, optical spectroscopy, and solution electrochemical studies. Organic field-effect transistors (OFETs) have been constructed based on drop-cast thin films and the performances as p-type semiconductor are presented. The chloro derivative was also copolymerized with 9,9-dioctyl-2,7-fluorenylenediboronic acid bis(1,3-propanediol) ester to give the alternating copolymer which exhibits blue photoluminescence in solution and blue-green electroluminescence in a solution processed organic light-emitting diode (OLED).