RELATIVE CROSS-SECTION AND TIME-RESOLVED FLUORESCENCE OF PORPHYRIN DNA COMPLEXES

Relative values have been obtained for the cross section of fluorescence of tetrakis(4-N-methylpyridyl)porphine and the zinc(II) complex with DNA. Time-resolved fluorescence spectra have been used to assign fluorescence of porphyrins which intercalate at or are externally bound to DNA. The experimental data suggest that an equilibrium distribution for intercalated and externally groove-bound to DNA of porphyrin is reached for r congruent-to 200 complexes. Radiative lifetimes of the various porphyrin species have been determined and evidence is found suggesting the contribution of non-linear effects to the intensity of laser induced fluorescence of r > 1000 complexes.