Excited-state intramolecular hydrogen atom transfer of curcumin in surfactant micelles.
Femtosecond fluorescence upconversion experiments were performed on the naturally occurring medicinal pigment, curcumin, in anionic, cationic, and neutral micelles. In our studies, the micelles are composed of sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB), and triton X-100 (TX-100). We demonstrate that the excited-state kinetics of curcumin in micelles have a fast (3-8 ps) and slow (50-80 ps) component. While deuteration of curcumin has a negligible effect on the fast component, the slow component exhibits a pronounced isotope effect of approximately 1.6, indicating that micelle-captured curcumin undergoes excited-state intramolecular hydrogen atom transfer. Studies of solvation dynamics of curcumin in a 10 ps time window reveal a fast component (< or = 300 fs) followed by a 8, 6, and 3 ps component in the solvation correlation function for the TX-100, DTAB, and SDS micelles, respectively.
Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
Ramkrishna
R
Adhikary
Philip J
PJ
Carlson
Tak W
TW
Kee
Jacob W
JW
Petrich
D003474:Curcumin / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D008823:Micelles; D017830:Octoxynol / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D006859:Hydrogen; D017830:Octoxynol; C022806:dodecyltrimethylammonium; D003474:Curcumin