Fluorescent properties and symmetry of the monodeprotonated form of 5,10,15,20-tetrakis-(4-N-methylpyridyl)-porphyrin

The spectral and kinetic properties of the monodeprotonated form of the cationic 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin (H2TMPyP) in solution are studied. The experimental results obtained are interpreted based on the four-orbital Gouterman model. It is established that the monodeprotonated form HTMPyP- can be assigned to the D4h symmetry point group, and has spectral and photophysical characteristics similar to the characteristics of the fluorescent metal complexes of H2TMPyP with relatively low electronegativity of the chelated metal ion. It is hypothesized that formation of the monodeprotonated form HTMPyP- is accompanied by a decrease in the oxidation potential of the porphyrin molecule. © 2006 Springer Science+Business Media, Inc.