Boosting anion sensing of O/S-bridged biscarbazole–triarylboron sensors via charge-transfer inhibition and the heavy-atom effect

Abstract

By combining O/S-bridged biscarbazole donors with a triarylboron acceptor, two donor–acceptor type F⁻ sensors, O-2B and S-2B, are developed. B-F⁻ coordination inhibits the strong charge-transfer effect, causing fluorescence changes. Owing to a larger energy gap, smaller oscillator strength and heavy-atom effect, S-2B exhibits greater fluorescence quenching and a lower F⁻ detection limit of 5.93 × 10⁻⁸ M than that of O-2B, demonstrating a superior sensing ability.