An Efficient Domino Protocol towards High Performance Organic Semiconductors: [1]Benzothiophene[3,2-b][1]benzothiophenes

Abstract

A highly efficient synthetic method toward [1]benzothiophene[3,2-b][1]benzothiophenes (BTBTs), high-performance organic semiconductors, through domino reaction has been developed. This protocol features inexpensive and readily available starting materials, catalyst-free, simple operation under air atmosphere, good yields, and wide substrate applicability. Notably, this method has become one of the most efficient methods for synthesizing BTBTs, which can construct four C–S and one C=C bonds through a domino reaction. Based on mechanistic study, two plausible reaction pathways were proposed: hydrosulfuric anion nucleophilic mechanism and sulfur free radical mechanism. The high potential application of this reaction was demonstrated by the gram-scale synthesis, transformations, and respectable photophysical property. More importantly, organic field-effect transistors (OFETs) prepared by spin-coating showed an average mobility of 1.143 cm2 V–1 s–1 for C8-BTBT and 0.032 cm2 V–1 s–1 for 3tBu-BTBT. Thus, this study has laid the foundation for the development of new BTBTs materials such as 3Cn-BTBT.