Lightening Flavin by Amination for Fluorescent Sensing

Abstract

Monitor of reactive oxygen species (ROS), such as O2•, etc. in organisms is of great significance, not only for their essential role in biological processes, but their excessive production may also result in many diseases. Flavin (FL) is a fluorophore naturally exists in flavoenzymes, and its fluorescent emission (FE) would become negligible when reduced. This enables the application of FL derivatives as fluorescent sensors for ROS. We presented a theoretical investigation to address the impact of amino substitution on the photophysical properties of amino flavins (AmFLs). Resulting from the interplay of electronic and positional effects, amination at C8 enhances the electronic coupling between ground state and first singlet excited state by enlarging the adiabatic energy change of electronic transitions and emission transition dipole moments, weakens the vibronic coupling by decrease the contribution of isoalloxazine to frontier molecular orbitals, redshifts the absorption band, and enhances fluorescent emission drastically in 8AmFL. The theoretically estimated fluorescent emission intensity of 8AmFL is ~40 times that of FL, rendering its potential application as fluorescent sensor.