Chemical Reactions Of The Isocyclic Ring In Pheophorbide A And The Synthesis Of Its Derivatives

The first section of this thesis summarized the research developments concerning the structure modification of chlorophyll a derivatives and their applications in photodynamic therapy and dye-sensitized solar cells. Great progress has been made in the synthesis and application of chlorophyll a derivatives, while a key challenge in this research area is the design and synthesis of near-infrared absorbing chlorophylls, which is desirable for their application as photosensitizers in photodynamic therapy and dye-sensitized solar cells.The structure changes of ring E in chlorophyll a derivatives influenced significantly for their absorption spectra, so the main contents of this thesis focused on the structure modification of ring E. Using methyl pheophorbide a(MPa) as the starting material, we studied the nucleophilic substitution under phase transfer condition and nucleophilic addition of ?-keto ester fragment in ring E; the aldol reaction and oxidation of methyl pyropheophorbide a(MPPa); the oxidation, reduction, Michael addition and 1,3-dipolar cycloaddition reactions of 132-methylene pyropheophorbide a; and the synthesis of aromatic ring fused chlorins based on the 1,5-difunctional structures derived from 132-methylene pyropheophorbide a via Michael addition.As a result, more than 80 novel compounds were synthesized, especially a series of benzo or pyrido fused chlorophylls were prepared firstly in history. We found that those aromatic ring fused chlorins showed atypical absorption spectra in comparison with the typical chlorophylls. Both of the Qx and Qy bands were found to be bathochromic shift significantly, which appeared as a continuous broad band in the range of 600-800 nm. This is the first example that chlorophylls have such atypical absorption spectra.The structures of new compounds were characterized by 1H NMR?UV-Vis?IR?MS and elemental analysis. The reaction mechanism and the optical characteristics of aromatic ring fused chlorophylls were also discussed.