Molecular design of cationic sensitizers carrying redoxactive intercalatorsubstituents: Towards recognition and photocatalytic cleavage of DNA

The novel pyrenyl substituted porphyrin ligand H-2(TPYRP) with TPYRP2- = di anion of meso-tetrakis (1-pyrenyl)porphyrin was synthesized and characteriz ed. A high-valent oxometallate complex of TPYRP was studied that can be pho tochemically activated by light in the long-wavelength visible spectral reg ion. Potential pathways of nucleic acid recognition and damage involving mi nor groove binding, intercalation and radical formation were investigated. In the presence of dioxygen, the system is expected to run through repeated redox cycles and thus it represents a functional photocatalytic model for "activated bleomycin" induced DNA strand cleavage.