13,13′‐Diphenalkyl β‐carotenes as pi‐stacking models of chlorophylls and carotenoids in photosynthesis

Abstract

Abstract2,7‐Diphenalkyl‐4‐octenedials 3 were prepared for the syntheses of 13,13′‐diphenalkyl β‐carotenes 1b–1d, which serve as the intramolecular models for the π‐stacking interactions of chlorophylls and carotenoids. The optimal tether length of the 13‐phenalkyl substituents in carotenes 1b–1d for the maximum π–π interactions with the polyene chain was decided to be a three‐methylene unit based on the most up‐field chemical shifts of the nearby protons of H11 and H15 by the magnetic anisotropic effect of benzene rings, which would provide a valuable information in the assembly of a single molecular light‐harvesting/energy‐transferring unit for artificial photosynthetic system.