EXCITON SPLITTING IN THE SPECTRA OF COVALENTLY LINKED PORPHYRINS

Absorption spectra are obtained for bis- and penta-porphyrin derivatives of meso-tetra-phenylporphyrins in which the porphyrin units are connected via 1,4 substituted benzene bridges. The results are interpreted with the help of the CNDO/S model and the Förster model using transition charges or dipoles of the monomer. An energy splitting of about 10 nm occurs in the Soret band. The polarization directions for the dimer were examined using the method of stretched polymer films. The energy splitting, intensities and polarization of the Soret band are explained by the transition dipole model. Dual fluorescence, indicating the existence of an emitting charge transfer state, was not found. © 1990.