[8π+2π] Cycloaddition of meso-Tetra- and 5,15-Diarylporphyrins: Synthesis and Photophysical Characterization of Stable Chlorins and Bacteriochlorins

The synthesis of new types of stable 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins and bacteriorins through [8 pi+2 pi] cycloaddition of diazafulvenium methides with porphyrins and chlorins is reported. Detailed absorption and fluorescence spectral and quantum yield measurements have been made on all new compounds. These show potential for various biomedical applications.