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-Nmethylpyridyl) 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. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 613–619, September–October, 2006.