Studies on curcumin and curcuminoids. XXXIX. Photophysical properties of bisdemethoxycurcumin.
Bottom Line: The steady-state absorption and fluorescence, as well as the time-resolved fluorescence properties of bisdemethoxycurcumin dissolved in several solvents differing in polarity and H-bonding capability were measured.The bisdemethoxycurcumin decay mechanisms from the S(1) state were discussed and compared with those of curcumin.The differences in S(1) dynamics observed between bisdemethoxy-curcumin and curcumin could be ascribed to a difference in H-bond acceptor/donor properties of the phenolic OH and a difference in strength of the intramolecular H-bond in the keto-enol moiety within the two molecules.
Affiliation: Department of Physics and Mathematics, University of Insubria and C.N.I.S.M.-C.N.R., Via Valleggio, 11- 22100 Como, Italy. firstname.lastname@example.orgShow MeSH
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Mentions: The fluorescence decay data were fitted, without deconvolving the system pulse response, to either single, double, or triple exponentials above a constant background, by minimizing the chi-square value through a Levenberg-Marquardt algorithm. For each decay, the number of exponential components was established by adding, one by one, exponential components to the fitting function until the fitting routine converged to yield two components of equal time constant. In Fig. 2 one of the decays obtained for bisDMC in DMSO is plotted, together with the corresponding fitting curve and residuals. The decay of bisDMC in DMSO was chosen as a paradigm of our ability of resolving decay components of negligibly low amplitude, such as the long-lived component with relative amplitude <1%. In Fig. 2 the best fitting curve obtained with a single-exponential decay model is also plotted. It is apparent that the quality of the two-exponential decay fit is superior.Fig. 2
Affiliation: Department of Physics and Mathematics, University of Insubria and C.N.I.S.M.-C.N.R., Via Valleggio, 11- 22100 Como, Italy. email@example.com