title: Effect of solvent on absorption and fluorescence spectra of a typical fluorinated azo dye for its acidic and basic structures.
abstract: The effect of 15 polar solvents on absorption and fluorescence energies of a typical fluorinated azo dye, 4-(2,3,5,6-tetrafluoro-pyridin-4-yl azo)-phenol, was reported for its acidic, MH, and basic, M, structures. For MH, the absorption energy is described on the basis of multi-linear equation with Taft's π* (solvent polarity) and β (hydrogen bond acceptor) parameters while the fluorescence energy varies rectilinearly with free energy of transferring the proton to the surrounding solvent, ΔG(t)°. For M, the hydrogen bonding donor ability of protic solvent, α, is a predominant factor which affects the absorption energy while in aprotic solvents, the absorption energy correlates linearly with Kirkwood function. As the ability of the solvent for hydrogen bonding increases, the absorption band width will increase in parallel with the transition energy.
authors.affiliation: Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, Egypt. dr_sthalim@yahoo.com
authors.forename: Shakir T
authors.initials: ST
authors.lastname: Abdel-Halim
mesh_terms: D000042:Absorption; D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D011522:Protons; D011725:Pyridines / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013053:Spectrophotometry / Q000379:methods; D013816:Thermodynamics
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D011522:Protons; D011725:Pyridines; D012997:Solvents; D005461:Fluorine