The fluorescence quenching phenomenon in newly synthesized blue fluorescence protein molecule caused by anchoring group substitution: a DFT and TD-DFT study

Abstract

The newly synthesized blue fluorescence protein (BFP) molecule combined with its derivatives were fully investigated using DFT and TD-DFT methods. The frontier molecular orbitals and NBO charges indicate that the intramolecular benzene ring in the BFP molecule can inhibit the charge redistribution after photo-excitation effectively. The substitution of malonic and malononitrile groups can create the fluorescence quenching phenomenon, which may be caused by their participation in the excited state charge redistribution and act as important electron-donating groups. Also, these substitutions can enhance the configuration stability in the S₁ state and hinder the formation of a metastable structure. The malononitrile group substitution can significantly decrease the energy barrier in the S₁ state and promote proton transfer.