Corrole

A corrole is an aromatic organic chemical, the structure of which is similar to the corrin ring, which is also present in cobalamin (vitamin B₁₂). The ring consists of nineteen carbon atoms, with four nitrogen atoms in the core of the molecule. In this sense, corrole is very similar to porphyrin, which is also an organic macrocycle but has twenty carbon atoms and is found in hemoglobin and chlorophyll.

Corroles can be prepared through organic synthesis by condensation reaction of a benzaldehyde with pyrrole in a water / methanol / hydrochloric acid mixture to an open-ring bilane (or tetrapyrrane) followed by oxidation and ring closure with p-chloranil:^[1]

Corrole has several important differences from porphyrin. The first is that it is normally a trianionic ligand with transition metals, while porphyrin is typically a dianionic ligand. As a result, corrole supports metals in higher oxidation states. The second difference from porphyrin is that, because the ring of corrole is smaller, there is slightly less space in the middle of it, which results in many metals sitting slightly out of the plane created by the four nitrogen atoms in the ring.

Corroles have been attached to a wide range of transition metals,^[2][3] main group elements,^[4] and more recently, lanthanides,^[5] actinides.^[6] and the diprotonated, neutral corrole radical.^[7] Additionally, corroles and their metal complexes have been demonstrated to be useful as imaging agents in tumor detection,^[8] for prevention of heart disease,^[9] in synthetic chemistry as oxo, imido, and nitrido transfer agents,^[10] and as catalysts for the catalytic reduction of oxygen to water,^[11] and hydrogen production form water under aerobic conditions.

References

1. Efficient Synthesis of meso-Substituted Corroles in an H2O-MeOH Mixture Beata Koszarna and Daniel T. Gryko J. Org. Chem.; 2006; 71(10) pp 3707 - 3717. doi:10.1021/jo060007k
2. Aviv-Harel, I.; Gross, Z. (2009). "Aura of Corroles". Chem. Eur. J. 15: 8382–8394. doi:10.1002/chem.200900920.
3. Buckley, H. L.; Chomitz, W. A.; Koszarna, B.; Tasior, M.; Gryko, D. T.; Brothers, P. J.; Arnold, J. (2012). "Synthesis of lithium corrole and its use as a reagent for the preparation of cyclopentadienyl zirconium and titanium corrole complexes". Chem. Commun 48: 10766–10768. doi:10.1039/c2cc35984g.
4. Aviv-Harel, I.; Gross, Z. (2010). "Coordination chemistry of corroles with focus on main group elements". Coord. Chem. Rev. 255: 717–736. doi:10.1016/j.ccr.2010.09.013.
5. Buckley, H. L.; Anstey, M. R.; Gryko, D. T.; Arnold, J. (2013). "Lanthanide corroles: a new class of macrocyclic lanthanide complexes". Chem. Commun 49: 3104–3106. doi:10.1039/c3cc38806a.
6. Ward, A. L.; Buckley, H. L.; Lukens, W. W.; Arnold, J. (2013). "Synthesis and Characterization of Thorium(IV) and Uranium(IV) Corrole Complexes". J. Am. Chem. Soc. 135: 13965–13971. doi:10.1021/ja407203s.
7. Schweyen P, Brandhorst K, Wicht R, Wolfram B, Bröring M (2015). "The Corrole Radical". Angew. Chem. Int. Ed. 54 (28): 8213–8216. doi:10.1002/anie.201503624. PMID 26074281.
8. Agadjanian, H.; Ma, J.; Rentsendorj, A.; Valluripalli, V.; Youn, J.; Mahammed, A.; Farkas, D. L.; Gray, H. B.; Gross, Z.; Medina-Kauwe, L. K. (2009). "Tumor detection and elimination by a targeted gallium corrole". PNAS 106: 6105–6110. doi:10.1073/pnas.0901531106.
9. Haber, Adi; Ali, A. A.-Y.; Aviram, M.; Gross, Z. (2013). "Allosteric inhibitors of HMG-CoA reductase, the key enzyme involved in cholesterol biosynthesis". Chem. Commun 49: 10917–10919. doi:10.1039/c3cc44740e.
10. Palmer, J. H. (2012). "Transition Metal Corrole Coordination Chemistry". Struct. Bond. 142: 49–90. doi:10.1007/430_2011_52.
11. Dogutan, D. K.; Stoian, S. A.; McGuire, R.; Schwalbe, M.; Teets, T. S.; Nocera, D. G. (2011). "Hangman Corroles: Efficient Synthesis and Oxygen Reaction Chemistry". J. Am. Chem. Soc. 133: 131–140. doi:10.1021/ja108904s.