meso–meso‐Linked Diarylamine‐Fused Porphyrin Dimers

Abstract

A meso-meso-linked diphenylamine-fused porphyrin dimer and its methoxy-substituted analogue were synthesized from a meso-meso-linked porphyrin dimer by a reaction sequence involving Ir-catalyzed β-selective borylation, iodination, meso-chlorination, and S Ar reactions with diarylamines followed by electron-transfer-mediated intramolecular double C-H/C-I coupling. While these dimers commonly display characteristic split Soret bands and small oxidation potentials, they produced different products upon oxidation with tris(4-bromophenyl)aminium hexachloroantimonate. Namely, the diphenylamine-fused porphyrin dimer was converted into a dicationic closed-shell quinonoidal dimer, while the methoxy-substituted dimer gave a meso-meso, β-β doubly linked porphyrin dimer.

Synthesis of Porphyrinquinone and Doubly‐Fused Diporphyrin Quinone Through Oxidation of Diarylporphyrins Using a Hypervalent Iodine Compound

“…Other quinones corresponding to 5 and 6 were not obtained under any reaction conditions. Compound 5 could be an intermediate of 4 , which could be readily oxidized under the oxidative reaction conditions reported for its analogues . Attempts to obtain the triply‐linked analogue by the oxidation of 4 with PhI(OAc) 2 under similar conditions or using 2,3‐dichloro‐5,6‐dicyano‐ p ‐benzoquinone (DDQ)/Sc(OTf) 3 were unsuccessful.…”

“…Furthermore, the modified method unexpectedly afforded a novel quinone 4 derived from meso ‐ meso , β – β doubly‐linked diporphyrin as the sole byproduct. To date, only quinoid compounds derived from meso ‐ meso ‐linked and meso ‐ meso‐ , β – β‐, β′ – β′‐ triply‐linked diporphyrins ( 5 and 6 , Figure ) have been reported. Quinoids derived from doubly‐linked diporphyrin have not been reported to date, although Osuka's group and others have reported a similar type of porphyrin analogue 7 as well as related diporphyrins 8 and 9 (Figure ) .…”

Porphyrinoids as a platform of stable radicals

“…As a result of this success, the diarylamine-fused porphyrin dimers 10 and 11 were prepared and their oxidation to the corresponding diradicals was attempted. 11 Upon oxidation with magic blue, however, 10 and 11 were transformed into the partially fused dimer 12 and the closed-shell quinonoidal species 13 , respectively, instead of open-shell diradicals.…”

ABC–ABC‐Type Directly meso–meso Linked Porphyrin Dimers

“…Considering the solar energy distribution with a maximum at 500 nm, the splitting of the Soret band in m ‐ZnPD is beneficial to better light harvesting. The energy difference between the split Soret bands of m ‐ZnPD was determined to be 2170 cm −1 , which is comparable with that of meso – meso ‐linked diarylamine‐fused porphyrin dimer (2170 cm −1 ) . This large energy difference is attributed to electronic perturbation by the push–pull structure.…”