Tetrapyrollic photosensitizers and imaging agent compounds having A, B, C, and D rings and having a reduced B ring and an oxidized D ring. The compounds preferably have a purity of at least 95 percent and preferably have a fused system connected at an unsaturated carbon atom of the C ring nearest the D ring and at the unsaturated carbon atom between the C and D rings. The invention also includes a method of making the compounds at over 95 percent yield by starting with a B and D ring oxidized tetrapyrollic compound and dissolving it in a halogenated hydrocarbon solvent and treating it with sufficient nitroalkane solution of FeCl36H2O to oxidize the D ring and separating the resulting organic layer and drying.