Reagent-controlled chemo- and regioselective reduction of 5,15-diazaporphyrins has been developed. The selective reduction of carbon-carbon double bonds of diazaporphyrins provides 18 π aromatic isobacteriochlorin-type products, whereas the reduction of carbon-nitrogen double bonds leads to selective formation of 20 π N,N'-dihydrodiazaporphyrins in excellent yields. The distinct antiaromatic character of N,N'-dihydrodiazaporphyrins has been revealed. The free-base N,N'-dihydrodiazaporphyrin exhibits slower inner NH tautomerism than that in the corresponding 18 π porphyrins.

Treatment of meso-mesityl 5,15-diazaporphyrin with alkyllithiums in toluene at low temperature provided monoalkylated diazachlorins through highly regioselective nucleophilic addition at the β-position near the meso-nitrogen atom.

Diazachlorin and diazabacteriochlorin were prepared and their activity for photodynamic therapy was investigated.

3-Pyridyl-5,15-diazaporphyrin nickel(II) serves as a bidentate metalloligand for platinum(II), ruthenium(II), and rhenium(I) metal centers. Single-crystal X-ray diffraction analysis of these metal complexes unambiguously reveals the presence of a dative bond between the outer metal center and the meso-nitrogen atom. The UV/Vis absorption spectra of the complexes show substantially red-shifted bands which are perturbed by outer-metal coordination. This is due to the contribution of metal-to-ligand charge transfer interactions.