Synthesis of chlorophyll-a derivatives possessing (un)substituted 13~1-exo-methylene moiety and their optical properties

摘要

Chlorophyll-a derivatives possessing an un/mono/disubstituted methylene moiety at the 13~1-position were prepared by (un)substituted methylation of the 13-carbonyl group and successive dehydration. Substitution of the 13~1oxo to the methylene group slightly blue-shifted electronic absorption and emission bands in a solution and decreased chemical stability to give an oxidation product cleaved at the E-ring. Further mono/disubstitution at the methylene terminal increased wavelengths of absorption and emission maxima as well as oxidative tolerance.