title: Temperature dependence of the fluorescence properties of curcumin.
abstract: Steady-state and time-resolved techniques were employed to study the nonradiative process of curcumin dissolved in ethanol and 1-propanol in a wide range of temperatures. We found that the nonradiative rate constants at temperatures between 175-250 K qualitatively follow the same trend as the dielectric relaxation times of both neat solvents. We attribute the nonradiative process to solvent-controlled proton transfer. We also found a kinetic isotope effect on the nonradiative process rate constant of ~2. We propose a model in which the excited-state proton transfer breaks the planar hexagonal structure of the keto-enol center of the molecule. This, in turn, enhances the nonradiative process driven by the twist angle between the two phenol moieties.
authors: Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
authors: Yuval
authors: Y
authors: Erez
authors: Itay
authors: I
authors: Presiado
authors: Rinat
authors: R
authors: Gepshtein
authors: Dan
authors: D
authors: Huppert
mesh_terms: D003474:Curcumin / Q000737:chemistry*; D005453:Fluorescence; D015394:Molecular Structure; D013696:Temperature
chemical_list: D003474:Curcumin