A theoretical study of the UV/visible absorption and emission solvatochromic properties of solvent-sensitive dyes.
Using the density-functional vertical self-consistent reaction field (VSCRF) solvation model, incorporated with the conductor-like screening model (COSMO) and the self-consistent reaction field (SCRF) methods, we have studied the solvatochromic shifts of both the absorption and emission bands of four solvent-sensitive dyes in different solutions. The dye molecules studied here are: S-TBA merocyanine, Abdel-Halim's merocyanine, the rigidified amino-coumarin C153, and Nile red. These dyes were selected because they exemplify different structural features likely to impact the solvent-sensitive fluorescence of "push-pull", or merocyanine, fluorophores. All trends of the blue or red shifts were correctly predicted, comparing with the experimental observations. Explict H-bonding interactions were also considered in several protic solutions like H2O, methanol and ethanol, showing that including explicit H-bonding solvent molecule(s) in the calculations is important to obtain the correct order of the excitation and emission energies. The geometries, electronic structures, dipole moments, and intra- and intermolecular charge transfers of the dyes in different solvents are also discussed.
Department of Molecular Biology, TPC-15, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA. wengehan@scripps.edu
Wen-Ge
WG
Han
Tiqing
T
Liu
Fahmi
F
Himo
Alexei
A
Toutchkine
Donald
D
Bashford
Klaus M
KM
Hahn
Louis
L
Noodleman
D000042:Absorption; D005456:Fluorescent Dyes / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
D005456:Fluorescent Dyes; D012997:Solvents