Synthesis, Photophysical and Electrochemistry of Near-IR Absorbing Bacteriochlorins Related to Bacteriochlorophyll a

摘要

A series of new bacteriochlorins was synthesizednusing 132-oxo-bacteriopyropheophorbide a (derived from bacteriochlorophyllna) as a starting material, which on reacting with ophenylenediaminenand 1,10-diaminonaphthalene afforded highlynconjugated annulated bacteriochlorins with fused quinoxaline,nbenzimidazole, and perimidine rings, respectively. The absorptionnspectra of these novel bacteriochlorins demonstrated remarkablynred-shifted intense Qy absorption bands observed in the range ofn816−850 nm with high molar extinction coefficients (89,900−n136,800). Treatment of 132-oxo-bacteriopyropheophorbide a methyl ester with diazomethane resulted in the formation ofnbacterioverdins containing a fused six-membered methoxy-substituted cyclohexenone (verdin) as an isomeric mixture. The purenisomers which exhibit long-wavelength absorptions in the near-IR region (865−890 nm) are highly stable at room temperaturenwith high reactivity with O2 at the triplet photoexcited state and favorable redox potential and could be potential candidates fornuse as photosensitizers in photodynamic therapy (PDT).