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5,18‐Dimesitylorangarin and its BF2 complex were synthesized by double SNAr reaction of 3,5‐dibromo‐BODIPY with 2‐pyrrolydipyrrin as the first examples of meso‐aryl‐substituted orangarin. These orangarins, delineated as [20]pentaphyrin(1.0.1.0.0), are strongly antiaromatic but rather stable. The free base orangarin was coupled by oxidation with MnO2 to give a 11,11′‐linked dimer, a cyclooctatetraene(COT)‐centered trimer, and a spiro‐trimer. Fused COT‐centered 3H‐orangarin dimer was oxidized to the corresponding 2H‐orangarin dimer, which was further coupled to give a triply COT‐centered 2H‐orangarin tetramer. 3H‐Orangarin oligomers are all antiaromatic as evinced by extremely low‐field‐shifted 1H NMR signals of the inner NH and ill‐defined absorption spectra with broad tails. In contrast, COT‐centered 2H‐orangarin dimer and tetramer show moderately low‐field‐shifted NH signals and intense NIR absorbance over 900 nm, suggesting effective π‐conjugation through the COT bridge and almost non‐antiaromatic character. These orangarin oligomers exhibit many reversible redox potentials owing to the intramolecular electronic interactions. Regardless of the different aromatic characters, all the orangarin monomers and oligomers exhibit very rapid excited‐state decays. [ABSTRACT FROM AUTHOR]

Herein we report the first synthesis of a tetrabenzotetrathia[8]circulene by a "fold-in" type oxidative fusion reaction. Compared to the pristine tetrathia[8]circulene, the four-fold benzoannulation slightly weakened the antiaromatic character of the central COT ring. The tetrabenzotetrathia[8]circulene exhibited fluorescence at room temperature, and phosphorescence at 77 K with a phosphorescence quantum yield of 11.7%. [ABSTRACT FROM AUTHOR]

Carbazole‐incorporated smaragdyrin BF2‐complex 3 was synthesized by SNAr reaction of 3,5‐dibromo‐8‐mesityl‐BODIPY 1 with 3,6‐di(tert‐butyl)‐1,8‐di(pyrrol‐2‐yl)carbazole 2 as a nucleophile. Demetalation of 3 with ZrCl4 gave the corresponding smaragdyrin free base 4 in a good yield. Oxidations of 3 and 4 with MnO2 gave smaragdyrins 5 and 6, respectively, both followed by aromaticity switching, since the oxidized products showed a moderate paratropic ring current owing to their 20π‐electronic circuits. Further, treatment of 4 with [RhCl(CO)2]2 in the presence of NaOAc gave RhI complex 7, and oxidation of 3 with RuCl3 in the presence of triethylamine led to the formation of a spiro dimer product, 8. [ABSTRACT FROM AUTHOR]

Pyrrole‐sharing fused hybrids of NiII porphyrin with PdII N‐confused(NC)‐corrole and PdII NC‐oxaporphyrin were synthesized by post‐fabrication of NiII porphyrins. Specifically this consists of Friedel–Crafts type aromatic substitution reaction of meso‐free NiII porphyrin with α,α′‐dibromotripyrrin and Pd(OAc)2 assisted cyclization, and final heating to induce a Pd−C bond formation. NiII porphyrins fused with PdII NC‐corrole and with PdII NC‐oxaporphyrins show coplanar structures with a shared pyrrole unit. In these hybrids, the PdII NC‐oxaporphyrin is aromatic and the PdII NC‐corrole is moderately antiaromatic and these local electronic properties interact to influence the whole network. [ABSTRACT FROM AUTHOR]

Cyclic azobenzene‐BODIPY hybrids were synthesized via cyclization by 1) acid‐catalysed condensation of azobenzene‐bridged dipyrroles with 3,5‐di‐tert‐butylbenzaldehyde, 2) oxidation with DDQ, and 3) metalation with BF3 ⋅ Et2O. The structures of many cyclic hybrids have been confirmed by single crystal X‐ray analysis. The absorption spectra of the hybrids reveal the effective cyclic conjugation. The ultrafast measurements reveal that the photoexcited decays of these cyclic hybrids depend upon the ring size and connectivity. [ABSTRACT FROM AUTHOR]

Di(p‐benzi)[40]decaphyrin(1.0.0.0.0.1.0.0.0.0) BF2 complex and tris(p‐benzi)[60]pentadecaphyrin(1.0.0.0.0.1.0.0.0.0.1.0.0.0.0) BF2 complex were synthesized by Suzuki‐Miyaura coupling of α,α'‐diborylated tetrapyrrole BF2‐complex with 1,4‐diiodobenzene. Bis‐BF2 complex was converted to bis‐PdII complex via its free base. Macrocycles bis‐BF2 and tris‐BF2 complex take Möbius topology but are nonaromatic, since the macrocyclic conjugation is disrupted by the locally aromatic 1,4‐phenylene units. In contrast, bis‐PdII complex is a weakly Hückel 38π‐aromatic macrocycle as evinced by its red‐shifted, enhanced, and structured Q‐like bands and a small electrochemical HOMO‐LUMO gap. Interestingly, one 1,4‐pheylene part of bis‐PdII complex takes a quinonoidal distorted structure and the other takes a usual benzene structure in a figure‐eight conformation with Hückel topology. [ABSTRACT FROM AUTHOR]

Subporphyrin borenium cations with a carborane counterion have been prepared by treatment of B-methoxy subporphyrins with the silylium reagent Et(3)Si(CH(6)B(11)Br(6)). In contrast to the distinctly domed subphthalocyanine borenium cation, a nearly planar structure with sp(2) hybridized boron is found in the X-ray structure of the triphenylsubporphyrin borenium cation. The cations exhibit absorption and fluorescence spectra that are quite similar to those of B-methoxy subporphyrins. B-phenyl subporphyrins were prepared in good yield by reaction of subporphyrin borenium cations with phenyllithium.

Naphthalene‐ and phenanthrene‐fused [22]smaragdyrin BF2‐complexes were synthesized by 1) Suzuki‐Miyaura coupling of β‐brominated [22]smaragdyrin BF2 complexes with 2‐formylarylboronates, 2) Witting‐type methoxymethylenation of the formyl group, and 3) methanesulfonic acid‐catalyzed cyclization reaction. Subsequently these BF2 complexes were deboronized and oxidized to the corresponding antiaromatic [20]smaragdyrin free bases. The installed fused structures led to decrease of the aromatic characters of the [22]smaragdyrin BF2 complexes and the antiaromatic characters of the [20]smaragdyrin free bases. [ABSTRACT FROM AUTHOR]