BN-Functionalized Benzotrithiophene-Based Azaborines: Synthesis, Structures, and Anion Binding Properties.

Facile synthesis of BN-functionalized azaborines (4a-4c) was accomplished via Suzuki coupling reactions followed by the electrophilic C-H borylation of benzotrithiophene (BTT). The core structure of BTT enables multiple modifications at the three thiophene rings. Molecular structures of 4a-4c were confirmed by NMR, high-resolution mass spectrometry, and X-ray crystallographic analysis. Their electronic properties were also examined through photophysical and electrochemical measurements as well as density functional theory computations. The red-shifted absorption and emission of these molecules were demonstrated upon fluoride titration in response to anion binding, leading to a remarkable decrease of the oxidation potential in the electrochemical differential pulse voltammetry scans. This work may provide a new pathway to robust redox-active materials for catalytic applications.