Reaction of Corroles with Sarcosine and Paraformaldehyde: A New Facet of Corrole Chemistry

Details on the unexpected formation of two new (dimethylamino)methyl corrole isomers from the reaction of 5,10,15-tris(pentafluorophenyl)corrolatogallium(III) with sarcosine and paraformaldehyde are presented. Semi-empirical calculations on possible mechanism pathways seem to indicate that the new compounds are probably formed through a Mannich-type reaction. The extension of the protocol to the free-base 5,10,15-tris(pentafluorophenyl)corrole afforded an unexpected new seven-membered ring corrole derivative, confirming the peculiar behavior of corroles towards known reactions when compared to the well-behaved porphyrin counterparts.

Manganese corrole catalyzed selective oxidation of styrene to benzaldehyde: sodium nitrite functions as an oxidant and cocatalyst

Catalytic oxidation using manganese corrole is a hot topic of contemporary porphyrin chemistry, in which PhIO, TBHP, PhI(OAc)₂, KHSO₅ and m-CPBA are usually used as oxidants. This article reports the first selective oxidation of styrene to benzaldehyde using a manganese(III) corrole catalyst and sodium nitrite (NaNO₂) as oxidant and cocatalyst at room temperature. The yield was 158.1% in air and 96.5% under a nitrogen atmosphere, showing oxygen might be involved in the reaction and that NaNO₂ is an oxygen source and cocatalyst in the system. The peripheral electron-withdrawing substituents of the manganese corrole were favorable to the catalytic reaction. Radical inhibition and H₂¹⁸O experiments proved that the catalytic reaction was a free radical and hydrolysis-involved reaction.

Corroles at work: a small macrocycle for great applications

Corrole chemistry has witnessed an impressive boost in studies in the last 20 years, thanks to the possibility of preparing corrole derivatives by simple synthetic procedures. The investigation of a large number of corroles has highlighted some peculiar characteristics of these macrocycles, having features different from those of the parent porphyrins. With this progress in the elucidation of corrole properties, attention has been focused on the potential for the exploitation of corrole derivatives in different important application fields. In some areas, the potential of corroles has been studied in certain detail, for example, the use of corrole metal complexes as electrocatalysts for energy conversion. In some other areas, the field is still in its infancy, such as in the exploitation of corroles in solar cells. Herein, we report an overview of the different applications of corroles, focusing on the studies reported in the last five years.

Electrocatalytic Hydrogen Production by CN‑ substituted Cobalt Triaryl Corroles

Four cobalt corrole complexes bearing 0–3 cyano groups on the para-position of the three meso-phenyl rings of the macrocycle were synthesized, characterized and applied for electrocatalytic H2 production under both...

Hydrogen evolution catalysis by terminal molybdenum-oxo complexes

Stable complexes with terminal triply bound metal-oxygen bonds are usually not considered as valuable catalysts for the hydrogen evolution reaction (HER). We now report the preparation of three conceptually different (oxo)molybdenum(V) corroles for testing if proton-assisted 2-electron reduction will lead to hyper-reactive molybdenum(III) capable of converting protons to hydrogen gas. The upto 670 mV differences in the [(oxo)Mo(IV)]-/[(oxo)Mo(III)]-2 redox potentials of the dissolved complexes came into effect by the catalytic onset potential for proton reduction thereby, significantly earlier than their reduction process in the absence of acids, but the two more promising complexes were not stable at practical conditions. Under heterogeneous conditions, the smallest and most electron-withdrawing catalyst did excel by all relevant criteria, including a 97% Faradaic efficiency for catalyzing HER from acidic water. This suggests complexes based on molybdenum, the only sustainable heavy transition metal, as catalysts for other yet unexplored green-energy-relevant processes.

Synthesis of cobalt A2B triaryl corroles bearing aldehyde and amide pyridyl groups and their performance in electrocatalytic hydrogen evolution

Amide pyridyl groups on cobalt corroles may function as proton relay groups to facilitate the HER.