Singlet Oxygen Quenching Abilities of Carotenoids

摘要: The bimolecular rate constants kq for quenching of singlet oxygen (1Δg state) by 26 different natural and novel synthetic carotenoids were determined at 37 °C in a mixture chloroform ethanol. steady-state technique used involves the generation 1O2 thermal decomposition disodium 3,3′-naphtalene-1,4-diyl-dipropionate endoperoxide (NDPO2) detection its luminescence intensity 1270 nm. Excitation energies (π,π*, 11Ag → 11Bu) absorption maxima (430–590 nm) vary broadest range. Deeply coloured blue are also included studies first time. An empirical correlation between π,π* (11Ag excitation energy carotenoid structure (effective chain length Neff) was found: E(S) = 12642 cm−1 + 92027 × 1/Neff. ability investigated depends on their transition long wavelengths characteristic way showing as limiting factors either Arrhenius activation or diffusion-controlled rate. This dependence suspected relationship triplet E(T) energies, respectively, discussed.