The results of a temperature‐dependent and time‐dependent fluorescence intensity study of the emission of intercalated and externally bound tetrakis(4‐N‐methylpyridyl)porphine are analyzed in terms of an association model. This analysis allows one to estimate differences in the enthalpies and entropies of complex formation for the intercalated and externally bound porphyrin‐DNA systems. These results indicate that the externally bound porphyrin molecule is more strongly bound to the DNA molecule than is the intercalated porphyrin molecule. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 445–448, 1997

The results of a temperature-dependent and time-dependent fluorescence intensity study of the emission of intercalated and externally bound tetrakis(4-Nmethylpyridyl)porphine are analyzed in terms of an association model. This analysis allows one to estimate differences in the enthalpies and entropies of complex formation for the intercalated and externally bound porphyrin-DNA systems. These results indicate that the externally bound porphyrin molecule is more strongly bound to the DNA molecule than is the intercalated porphyrin molecule.