Carotenoids and related polyenes. Part 4.1 Synthesis of carotenoid analogues containing a conjugated carbonyl group and their fluorescence properties

Abstract

Fluorescence properties of several synthetic carotenoid analogues have been investigated in order to assess the relationship between molecular structures and function as a photosynthetic antenna. The origin of fluorescence is determined by two factors; the length of the conjugated double bond system and the presence of a carbonyl group. For efficient energy transfer to chlorophyll a, eight conjugated double bonds and an associated carbonyl group are required, which ensures that fluorescence occurs from the S₁ state.