Radical ions derived from photosynthetic polyenes

Abstract

The radical cations and anions of the photosynthetic polyenes: all-trans-β-carotene, 15,15′-cis-β-carotene and all-trans-lycopene have been produced and characterised in hexane, cyclohexane and methanol (anions only) using pulse radiolysis techniques. Both types of radicals are believed to be monomeric and have intense absorptions in the near infrared, their maximum extinctions being in excess of 10⁵ dm³ mol^–1 cm^–1. The cationic and anionic band maxima are well separated, the cationic maxima lying about 150 nm to the red of the anionic maxima.