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Skeletal formula of porphyrazine
Space-filling model of the porphyrazine molecule
IUPAC name
Other names
5,10,15,20-Tetraazaporphine; Tetraazaporphine; Tetraazaporphyrin; Tetrazaporphin
3D model (JSmol)
Molar mass 314.31 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Porphyrazines, or tetraazaporphyrins, are tetrapyrrole macrocycles similar to porphyrins and phthalocyanines. Pioneered by Sir R. Patrick Linstead as an extension of his work on phthalocyanines,[1] porphyrazines differ from porphyrins in that they contain -meso nitrogen atoms, rather than carbon atoms, and differ from phthalocyanines in that their β-pyrrole positions are open for substitution. These differences confer physical properties that are distinct from both porphyrins and phthalocyanines.[2]


Porphyrazines are prepared by magnesium templated cyclization of maleonitriles.[3] Cross-cyclization with phthalonitrile or diiminoisoindole derivatives is possible introducing a flexibile synthetic route that has led to the synthesis of porphyrazines with peripheral heterocyclic rings,[4] heteroatom substituents (S, O, N),[5] peripherally bound metal atoms,[6] and mixed -benzo porphyrazine systems.[7]

Optical properties[edit]

Porphyrazines are most well known for their intense electronic absorption throughout the UV, visible, and NIR spectral regions. Electronic absorption spectra for porphyrazines are similar to those of phthalocyanines,[8] with an intense Soret band (λ ≈ 300 - 400 nm) and Q-band (λ > 600 nm).[7][9]

Porphyrazines exhibit fluorescence from the first excited singlet state (S1 → S0)[10] at visible and NIR wavelengths which is typical of tetrapyrrole macrocycles. Dual-emission from organic fluorophores is not common but, as observed in phthalocyanines,[11][12] violet emission from an upper excited state (S2 → S0) is observed in porphyrazines.[13][14][15]


  1. ^ Cook, A. H.; Linstead, R. P., "Phthalocyanines. XI. The preparation of octaphenylporphyrazines from diphenylmaleinitrile." J. Chem. Soc. 1937, 929-933.DOI: 10.1039/JR9370000929
  2. ^ Ghosh, A.; Fitzgerald, J.; Gassman, P.G.; Almof, J. Inorg. Chem., 1994, 33, 6057-6060. DOI: 10.1021/ic00104a014
  3. ^ Kobayashi, N. Meso-Azaporphyrins and Their Analogues. In The Porphyrin Handbook, Kadish, K.M.; Smith, K.M.; Guilard, R., Eds.; Academic Press; 1999, Vol. 2, pp. 317-321.
  4. ^ Angeloni, S.; Ercolani, C., New classes of porphyrazine macrocycles with annulated heterocyclic rings. Journal of Porphyrins and Phthalocyanines, 2000, 4, 474–483.
  5. ^ Michel S.L.J.; Hoffman B.M. Baum S.M.; Barrett A.G.M.; "Peripherally functionalized porphyrazines: Novel metallomacrocycles with broad, untapped potential;" Progress in Inorganic Chemistry, 50: 473-590, 2001.
  6. ^ For example: Zhao, M; Zhong, C.; Stern, C.; Barrett, A.G.M.; Hoffman, B.M., Synthesis and Properties of Dimetallic M1[Pz]-M2[Schiff Base] Complexes. Inorg. Chem., 2004, 43, 3377-3385.
  7. ^ a b Miwa, H., Ishii, K., Kobayashi, N., Electronic Structures of Zinc and Palladium Tetraazaporphyrin Derivatives Controlled by Fused Benzo Rings. Chemistry - A European Journal, 2004,10, 4422–4435.
  8. ^ Kobayashi, N. and H. Konami (1996) Molecular orbitals and electronic spectra of phthalocyanine analogues. In Phthalocyanines: Properties and Applications, Vol. 4 (Edited by C. C. Leznoff and A. B. P. Lever), pp. 343–404. VCH Publishers, Inc., New York.
  9. ^ Linstead, R. P.; Whalley, M., Conjugated Macrocycles. Part XXI Tetrazaporphin and its Metallic Derivatives. J. Chem. Soc. 1952, 4839-4844.
  10. ^ Shushkevich, I.K.; Pershukevich, P.P.; Stupak, A.P.; Solov'ev, K.N.; Journal of Applied Spectroscopy, 2005, 72, 767-770.
  11. ^ Chahraoui, D., Valat, P., and Kossanyi, J., Fluorescence of Phthalocyanines: Emission from an Upper Excited State. Res. Chem. Intermed., 1992, 17, 219-232.
  12. ^ Kaneko, Y., Nishimura, Y., Takane, N., Arai, T., Sakuragi, H., Kobayashi, N., Matsunaga, D., Pac, C., and Tokumaru, K., Violet emission observed from phthalocyanines. J. Photochem. Photobiol. A, 1997, 106, 177-183.
  13. ^ Lee, S., White, A.J.P., Williams, D.J., Barrett, A.G.M., and Hoffman, B.M. Synthesis of Near-IR Absorbing/Emitting Porphyrazine Derivatives with Tunable Solubility. J. Org. Chem., 2001, 66, 461-465.
  14. ^ Lee, S.; Stackow, R.; Foote, C.S.; Barrett, A.G.M.; Hoffman, B.M.; Tuning the Singlet Oxygen Quantum Yield of Near-IR-absorbing Porphyrazines. Photochem. Photobio., 2003, 77, 18-21.
  15. ^ Trivedi, E.R., Vesper, B.J., Weitman, H., Ehrenberg, B., Barrett, A.G.M., Radosevich, J.A., and Hoffman, B.M., Chiral bis-Acetal Porphyrazines as Near-infrared Optical Agents for Detection and Treatment of Cancer. Photochem. Photobio., 2010, 86, 410-417.