Study of the Mechanism of Electron-Transfer Quenching by Boron−Nitrogen Adducts in Fluorescent Sensors

The mechanism of the change in fluorescence quenching by the amine in boronic acid-based carbohydrate sensor molecules has been explored using density functional theory (DFT). The geometric constraints of the system have been studied in both intra- and intermolecular model systems of the boron−nitrogen (B−N) bonding interaction. The effect of the B−N bonding on the rate of electron-transfer (ET) quenching of the anthracene acceptor by an amine donor is considered using a theoretical model. The results suggest a new mechanism other than B−N bond strength change for fluorescent switching in biosensors that involve interaction of boron and nitrogen affected by boronate ester formation.