Crystallization induced enantiomer division (CIED) of π-expanded benzoacridine regioisomers

Abstract Asymmetrical isomerization with prochiral π-distortion is useful to precisely construct nonplanar arenes as promising wide band gap (>2.2 eV) semiconductors. A series of asymmetrical benzoacridine regioisomers (ADs) were designed and obtained via a two-step procedure including Ullmann C-N coupling, intramolecular Friedel-Crafts ortho -aroylation. Interestingly, crystallization induced enantiomer division (CIED) of four prochiral ADs was observed. The corresponding ten divided enantiomers or diastereoisomers were carefully anatomized and distinguished from their “monozygotic and/or dizygotic twins” in crystals. The precise structures of four ADs were confirmed by 1 H NMR, 13 C NMR, HiRes MALDI-TOF MS, FT-IR and single crystal X-Ray diffraction. According to the absorbance spectra, ADs possess wide optical band gaps (2.90–2.98 eV) in film state and potential ability for high performed electronic devices.