Influence of macrocycle protonation on the photophysical properties of porphyrins

Abstract

Analysis of the relationship between the molecular structure of porphyrins and the spectral features of their monoand diprotonated forms in solution is presented. The evolution of the concept of the role of acid-base equilibria in the formation of the spectral properties and the excitation energy deactivation pathways in porphyrins are reviewed. The trends observed in the fluorescence and intersystem crossing quantum yields on going from free base porphyrins to their mono-and diprotonated forms are analyzed, and the mechanisms involved are discussed. © ISUCT Publishing.