Theoretical Design of Near-Infrared Fluorescent Sensor for F Anion Detection Based on 10-Hydroxybenzo[h]quinoline Backbone

Proper design and development of near-infrared (NIR) fluorescent sensors is very important for applications in vivo. In this work, we theoretically designed a ratiometric and NIR fluorescent sensor based on the 10-hydroxybenzo[ h ]quinoline (HBQ) backbone via systematically investigating the substituent effects of electron-donating groups (-NH 2 , -CH 3 , -C(CH 3 ) 3 ) and electron-withdrawing groups (-NO 2 , -CN, -F, -Cl, -CF 3 ) at the proton donor site on the proton transfer process in HBQ in both the S 0 and the S 1 states. According to the calculated potential energy profiles along the proton transfer as well as the photophysical properties among all the derivatives, we successfully screened out that 7NH 2 -HBQ is a promising fluorescent sensor exhibiting the near IR emission spectra accompanied by the large Stokes shift. The potential use of 7NH 2 -HBQ for F - detection among anions (F - , Cl - , and Br - ) was further studied, and the results showed that 7NH 2 -HBQ is very sensitive and selective toward F - based on the intermolecular hydrogen bonding interaction between F - and OH bond, forming a new complex FAC S 0 . The ratiometric change in the fluorescence intensity could be induced by the H-F bond transfer from the O atom to the N atom in the S 1 state.