Three novel mono BN substituted derivatives (PDI-BN1, PDI-BN2 and PDI-BN3) of symmetrical and asymmetrical perylene diimides were designed and efficiently synthesised using a concise synthetic strategy. These derivatives exhibited orange fluorescence, with their properties finely adjustable by integrating various fused aryl rings. Except for F⁻ ions, these derivatives have shown no affinity for other anions. (Image credit: Feng Liu.)