Photophysical properties of two novel tetraphenylporphyrins substituted by guanidiniocarbonyl and monocyclic guanidine groups

Abstract

Photophysical properties of two novel guanidiniocarbonyl (I) and monocyclic guanidine (II) tetraphenylporphyrins and their interaction with DNA were investigated by steady-state and time-resolved absorption and emission spectroscopies. I stays predominantly monomeric in aqueous solutions. It produces singlet oxygen with high quantum yield (φΔ = 0.67) that is typical for monomeric porphyrins. The electronic absorption spectra of I are not influenced by interaction with DNA. This is in contrast with monomeric tetratolylporphyrins bearing phosphonium, ammonium and pyridinium groups where the formation of stable complexes with DNA is accompanied by a characteristic red shift of the Soret band. II extensively forms H-and J-aggregates, which do not produce singlet oxygen (φΔ < 0.01). In the presence of DNA only a small fraction of II remains in monomeric form that is bound to DNA exterior.