AM1 electron density and NMR spectral studies of carotenoids with a strong terminal electron acceptor

Abstract

NMR spectral analyses of 7′,7′-dicyano-7′-apo-β-carotene (1), which was synthesized to assess the effect of a terminal strong electron acceptor on the structure of carotenoids and the molecular features which control their photochemical properties, are presented. AM1 Molecular orbital calculated electron density differences for 1 and 8′-apo-β-caroten-8′-al (2) have been found to correlate with the differences in 13C NMR chemical shifts using β-carotene (3) as a reference.