Diindole[3,2-b:4,5-b′]pyrrole as a chromophore containing three successively fused pyrroles: synthesis, optoelectronic properties and π-functionalization

Diindole[3,2-b:4,5-b']pyrrole (DIP) is an interesting chromophore containing three successively fused pyrrole rings. However, its basic properties and further pi-functionalization have been rarely explored. In this article, two DIP compounds with alkyl or aromatic substituents at the central N position were successfully prepared. The preliminary optoelectronic properties of them also were studied. The property of possessing two reversible oxidation redox couples also agrees with their electron-rich nature. Similar to the alkyl case, the aromatic substitution at the central N position has subtle influence on DIP basic optoelectronic properties. Furthermore, these two compounds can be easily pi-modified via the attachment of various pi moieties at 2,9 or 3,8 positions of DIP skeleton. Compared with that at 2,9 positions, pi-functionalization at 3,8 positions showed a much better pi-extension effect. (C) 2015 Elsevier Ltd. All rights reserved.