Phosphorescence of octaethylchlorine, isobacteriooctaethylchlorine and their metal complexes]

The phosphorescence of dihydrooctaethylporphin (octaethylchlorin or OEC), of its complexes with magnesium, zinc, copper and palladium, and of zinc and palladium complexes of isobacteriooctaethylchlorin (5,6,7,8-tetrahydrooctaethylporphin with adjacent hydrogenated pyrrole rings or THOEP-ADJ) has been investigated. The phosphorescence spectra and phosphorescence excitation spectra as well as the ratio of fluorescence and phosphorescence yields and the triplet state lifetume have been measured. It has been shown that the singlet-triplet interval is about 4100 cm-1 for OEC complexes and about 4300 cm-1 for THOEP-ADJ complexes, and depends wealky on the nature of the metal atom forming the complex. The triplet level position of chlorophyll alpha is discussed. It is concluded that the maximum of chlorophyll alpha phosphorescence spectrum must be located at 895 nm.