1. Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan;2. Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University, Otsu, Shiga 520-2194, Japan
Abstract:
Chlorophyll-a derivatives possessing an un/mono/disubstituted methylene moiety at the 131-position were prepared by (un)substituted methylation of the 13-carbonyl group and successive dehydration. Substitution of the 131-oxo 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.