Dramatic changes in the excited-state behaviour of the green fluorescent protein chromophore by a strong π-donating group through significantly lowering the excited-state potential energy surface with photoinduced intramolecular charge transfer.

Abstract

A strong π-donating group like p-NMe2 dramatically changes the excited-state behavior of the green fluorescent protein (GFP) chromophore, such as realizing charge-transfer absorption and executing significant photoinduced intramolecular charge transfer (ICT), which makes a planar first singlet (S1) excited-state minimum disappear and significantly lowers the S1 excited-state potential energy surface (PES), leading to barrierless τ-torsion and φ-torsion excited-state relaxation and eliciting the φ-torsion S1 excited-state minimum. This finding is critical since a strong π-donating group like p-NMe2 may do the same things to other fluorophores.