Cis-Trans Carotenoids in Photosynthesis: Configurations, Excited-State Properties and Physiological Functions

Abstract

Correlations between the 1H-NMR, electronic-absorption and resonance-Raman spectra and the cis-trans configurations have been identified for β-carotene and other carotenoids: (1) the chemical shifts of the olefinic 1Hs in NMR, (2) the wavelength of the A g − →B u + absorption and the relative intensity of the A g − →A g + vs. the A g − →B u + absorption in electronic absorption, and (3) the C=C stretching frequency, the relative intensity of the C10–C11 vs. the C14–C15 stretching vibration and the appearance of key modes in resonance Raman can be used to identify the all-trans or a mono-cis configuration.