inorganic chemistry

Keywords:Bacteriochlorin; Photodynamic therapy; Reactive
oxygen species; Photodecomposition.

I. Introduction

Porphyrins and their derivatives play critical roles in many
biological functions. Some of the most remarkable examples are
protoporphyrin IX and its iron complex that constitutes the heme
prosthetic group, and the magnesium complexes of pheophytina
and bacteriopheophytinathat are known as chlorophyllaand
bacteriochlorophyll a, respectively. These natural compounds
are illustrated inFig. 1 together with the structure of porphin,

FIG. 1. Structure and absorption maxima of some natural porphyrins
andtheirderivatives.Alsoshownisthestructureofthesimplestporphyrin,
called porphin, and the names commonly given to substitution positions.

188 LUIS G. ARNAUT