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The synthesis of antiaromatic NiII–norcorroles having primary, secondary, and tertiary alkyl groups at the reactive meso‐positions was attempted. Reductive coupling of a NiII–dipyrrin precursor provided NiII–meso‐dihexylnorcorrole, which underwent substantial degradation on silica gel. Introduction of tert‐butyl groups was unsuccessful due to the difficult preparation of the corresponding dipyrrin precursor. Meanwhile, NiII–norcorroles with isopropyl and cyclohexyl groups were isolated as stable molecules under ambient conditions. Furthermore, we found that oxidation of NiII–meso‐dialkylnorcorroles with hydrogen peroxide in the presence of sodium carbonate gave NiII–5‐oxaporphyrins(2.0.1.0). In contrast, oxidation of NiII–meso‐dimesitylnorcorrole under the same reaction conditions gave 10‐oxaporphyrin(1.1.1.0). The contrasting reactivity can be attributed to the steric congestion around the meso‐positions. [ABSTRACT FROM AUTHOR]

While hydrogenated porphyrins are abundant in natural and synthetic compounds, antiaromatic hydrogenated porphyrinoids have not been synthesized to date. Here, we report bacteriochlorin-like NiII tetrahydronorcorrole complexes as the first examples of antiaromatic porphyrinoids that contain saturated pyrrole units. [ABSTRACT FROM AUTHOR]

Norcorrole is a stable 16π-antiaromatic porphyrinoid that exhibits characteristic reactivities and physical properties. Here, we disclose the reaction of Ni(II) norcorroles with alkyl radicals derived from azo radical initiators. The radical selectively attacked the distal α-position relative to the meso -position to construct a nonaromatic bowl-shaped structure. The photophysical and electrochemical properties of the obtained radical adducts were compared to those of the parent Ni(II) norcorrole. The radical reactivity of Ni(II) norcorroles was investigated by density functional theory (DFT) calculations., (Copyright © 2024, Shafie et al.)

Recently, π-π stacked antiaromatic π-systems have received considerable attention because they can exhibit stacked-ring aromaticity due to substantial intermolecular orbital interactions. Here, we report three antiaromatic norcorrole dimers that self-assemble to form supramolecular architectures through chiral self-sorting. A 2,2'-linked norcorrole dimer with 3,5-di-tert-butylphenyl groups forms a π-stacked dimer both in solid and solution states via homochiral self-sorting. Its association constant in solution is (3.6±1.7)×10 5  M -1 at 20 °C. In the solid state, 3,3'-linked norcorrole dimers with 3,5-di-tert-butylphenyl and phenyl groups afford macrocyclic and helical supramolecular assemblies via heterochiral and homochiral self-sorting, respectively. Notably, the subtle modification in the substituent resulted in a complete change in the structure of the aggregates and the chiral self-sorting mode. The present findings demonstrate that structural manipulation in antiaromatic monomer units leads to the formation of various supramolecular assemblies on the basis of the attractive interactions between antiaromatic π-systems., (© 2024 Wiley-VCH GmbH.)

The synthesis of antiaromatic Ni II -norcorroles having primary, secondary, and tertiary alkyl groups at the reactive meso-positions was attempted. Reductive coupling of a Ni II -dipyrrin precursor provided Ni II -meso-dihexylnorcorrole, which underwent substantial degradation on silica gel. Introduction of tert-butyl groups was unsuccessful due to the difficult preparation of the corresponding dipyrrin precursor. Meanwhile, Ni II -norcorroles with isopropyl and cyclohexyl groups were isolated as stable molecules under ambient conditions. Furthermore, we found that oxidation of Ni II -meso-dialkylnorcorroles with hydrogen peroxide in the presence of sodium carbonate gave Ni II -5-oxaporphyrins(2.0.1.0). In contrast, oxidation of Ni II -meso-dimesitylnorcorrole under the same reaction conditions gave 10-oxaporphyrin(1.1.1.0). The contrasting reactivity can be attributed to the steric congestion around the meso-positions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel synthetic procedure for meso-aryl-substituted corrphycenes has been developed. Suzuki-Miyaura coupling of α,α'-dibromodipyrrin with vic-diborylalkene and o-diborylbenzene afforded ethenylene- and phenylene-bridged bisdipyrrins, respectively, which were transformed to the corresponding corrphycenes upon treatment with palladium acetate. The bridging units significantly affect the macrocyclic π-conjugation circuits, thus changing the aromatic characters and absorption features of corrphycenes.