TY - JOUR
AU - Yangyi Liu
AU - Zhuang Chen
AU - Xueli Wang
AU - Simin Cao
AU - Jianhua Xu
AU - Ralph Jimenez
AU - Jinquan Chen
AB - Biliverdin is a bile pigment that has a very low fluorescence quantum yield in solution, but serves as a chromophore in far-red fluorescent proteins being developed for bio-imaging. In this work, excited-state dynamics of biliverdin dimethyl ether (BVE) in solvents were investigated with femtosecond (fs) and picosecond (ps) time-resolved absorption and fluorescence spectroscopy. This study is the first fs timescale investigation of BVE in solvents, and therefore revealed numerous dynamics that were not resolved with previous, 200-ps time resolution measurements. Viscosity- and isotope-dependent experiments were performed to identify the contributions of isomerization and proton transfer to the excited-state dynamics. In aprotic solvents, a ~2 ps non-radiative decay accounts for 95% of the excited-state population loss. In addition, a minor ~30 ps emissive decay pathway is likely associated with an isomerization around the C15=C16 double bond that results in a flip of the D-ring. In protic solvents, the dynamics are more complex due to hydrogen bonding. In this case, the ~2 ps decay pathway is a minor channel (15%), whereas ~70% of the excited-state population decays through an 800-fs emissive pathway. The ~30 ps timescale associated with isomerization is also observed in protic solvents. The most significant difference in protic solvents is the presence of a >300 ps timescale in which BVE can decay through an emissive state, in parallel with excited-state proton transfer to solvent. Interestingly, a small fraction of a luminous species, which we designate lumin-BVE (LBVE), is present in protic solvents.
BT - Physical Chemistry Chemical Physics
DA - 2020-08
DO - 10.1039/D0CP02971H
N2 - Biliverdin is a bile pigment that has a very low fluorescence quantum yield in solution, but serves as a chromophore in far-red fluorescent proteins being developed for bio-imaging. In this work, excited-state dynamics of biliverdin dimethyl ether (BVE) in solvents were investigated with femtosecond (fs) and picosecond (ps) time-resolved absorption and fluorescence spectroscopy. This study is the first fs timescale investigation of BVE in solvents, and therefore revealed numerous dynamics that were not resolved with previous, 200-ps time resolution measurements. Viscosity- and isotope-dependent experiments were performed to identify the contributions of isomerization and proton transfer to the excited-state dynamics. In aprotic solvents, a ~2 ps non-radiative decay accounts for 95% of the excited-state population loss. In addition, a minor ~30 ps emissive decay pathway is likely associated with an isomerization around the C15=C16 double bond that results in a flip of the D-ring. In protic solvents, the dynamics are more complex due to hydrogen bonding. In this case, the ~2 ps decay pathway is a minor channel (15%), whereas ~70% of the excited-state population decays through an 800-fs emissive pathway. The ~30 ps timescale associated with isomerization is also observed in protic solvents. The most significant difference in protic solvents is the presence of a >300 ps timescale in which BVE can decay through an emissive state, in parallel with excited-state proton transfer to solvent. Interestingly, a small fraction of a luminous species, which we designate lumin-BVE (LBVE), is present in protic solvents.
PB - "The Royal Society of Chemistry"
PY - 2020
SP - 19903
EP - 19912
T2 - Physical Chemistry Chemical Physics
TI - Ultrafast spectroscopy of biliverdin dimethyl ester in solution: pathways of excited-state depopulation
UR - http://dx.doi.org/10.1039/D0CP02971H
VL - 22
ER -