Syntheses of Chlorophyllous Chlorin Derivatives with Aromatic Ring-Fused Imidazole Structural Unit

Abstract

Using pheophorbide-a methyl ester as starting material, the formyl group and α-diketone moiety were introduced into the water-soluble end of N21-N23axis at different positions by the structural transformation on exocyclic ring. Furthermore, using the Phillps-Ladenburg-like reaction of active functional groups in chlorophyll chlorins with various aromatic o-diamines, the aromatic ring-fused imidazole structural units were created in linkage or fused manner, and a series of unreported chlorin derivatives that contain aryl-fused imidazol unit were finally synthesized. Besides, the relevant reaction mechanism was analyzed, and the absorption properties of these imidazolized products were discussed. The chemical structures of all newly synthesized compounds were characterized by elemental analysis, MS, UV-Vis, IR and 1H NMR spectra.