Meta and para effects in the ultrafast excited-state dynamics of the green fluorescent protein chromophores.
Femtosecond transient absorption and fluorescence upconversion experiments have been performed to investigate the photoinduced dynamics of the meta isomer of the green fluorescent protein chromophore, m-HBDI, and its O-methylated derivative, m-MeOBDI, in various solvent mixtures at neutral, acidic, and basic pH. The para isomer, p-HBDI, and its O- and N-methylated derivatives, p-MeOBDI and p-HBDIMe(+), were also studied for comparison. In all cases, fast quenching of the excited S1 state by internal conversion (IC) to the ground state was observed. In the para compounds, IC, presumably promoted by the internal twisting, arises in <1 ps. A similar process takes place in the meta compounds in nonaqueous solvents but with notably slower kinetics. In aqueous solutions, the meta compounds undergo ultrafast intermolecular excited-state proton transfer that competes with isomerization.
Solntsev
Kyril M
KM
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA. solntsev@gatech.edu
Poizat
Olivier
O
Dong
Jian
J
Rehault
Julien
J
Lou
Yongbing
Y
Burda
Clemens
C
Tolbert
Laren M
LM
D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D048288:Imidazolines / Q000737:chemistry; D007536:Isomerism; D008956:Models, Chemical; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet
C502519:4-hydroxybenzylidene-1,2-dimethylimidazolinone; D005456:Fluorescent Dyes; D048288:Imidazolines; D012997:Solvents; C485192:green fluorescent protein, Aequorea victoria; D049452:Green Fluorescent Proteins