Texaphyrins and uses thereof

A texaphyrin having substituents containing ethoxy groups, methods for using texaphyrins in photodynamic therapy, and cleavage of a polymer of deoxyribonucleic acid are disclosed. The in vivo treatment of tumors and atheroma is demonstrated using Lu(III)texaphyrin complexes. A preferred method of use is the site-specific cleavage of a polymer of deoxyribonucleic acid and a preferred texaphyrin is a derivatized texaphyrin having binding specificity, in particular, a texaphyrin covalently coupled to a site-directing molecule, preferably an oligonucleotide.