Correlation of fluorescence quenching in carotenoporphyrin dyads with the energy of intramolecular charge transfer states. Effect of the number of conjugated double bonds of the carotenoid moiety
作者:Fernando Fungo、Luis Otero、Edgardo Durantini、William J. Thompson、Juana J. Silber、Thomas A. Moore、Ana L. Moore、Devens Gust、Leonides Sereno
DOI:10.1039/b209694c
日期:2003.1.16
The electrochemistry of a series of non-symmetric synthetic carotenoids, with different conjugated double bounds chain lengths (5 to 11) is reported. The values of the first oxidation potentials of the carotenoids were evaluated by digital simulation of the experimental cyclic voltammograms. There is a clear relationship between calculated (AM1) HOMO energies of neutral carotenoids with their conjugated chain length, indicating that the change of solvation energy of carotenoids is small throughout the series, and that the electron-donating ability of carotenoids increases with the length of the conjugated chain. Carotenoids had been previously used to design carotenoporphyrin (C–P) molecular dyads. Carotenoid oxidation potentials and the reduction potential of the porphyrin moiety were used in order to calculate the energy of intramolecular charge transfer state in C–P dyads. Correlation of porphyrin fluorescence quenching of these dyads with the energy of the charge transfer state is reported, showing that effective quenching is only possible for carotenoids with more than eight conjugated double bonds.
A method of pigmenting the egg yolk, integuments and/or subcutaneous fat of poultry and the meat and/or integuments of fish and crustacea involves including in the feed of the poultry, fish or crustacea one or more of the carotenoids 2'-dehydroplectaniaxanthin, 1-hydroxy-3,4-didehydro-1,2-dihydro-Ψ,Ψ-caroten-2-one, desmethylspheroidenone, spheroidenone, 5'-hydroxy-5',6'-dihydro-4'-apo-β-caroten-6'-one, 1'-hydroxy-3',4'-didehydro-1',2'-dihydro-β,Ψ-carotene-4,2'-dione and 5'-hydroxy-5',6'-dihydro-4'-apo-β-carotene-4,6'-dione. Also embraced by the invention are the pertinent carotenoid-enriched feed for poultry, fish or crustacea, the premixes for incorporation in such feeds and beadlets containing one or more of these carotenoids for incorporation in such premixes, the use of the carotenoids in the pigmenting method and the four new carotenoids of the seven aforementioned carotenoids. The new carotenoids can be produced by condensing in each case an appropriate aldehyde with 3-hydroxy-3-methyl-2-butanone, thereby forming the characteristic terminal 2-hydroxy-2-methyl-propionyl group.