A Fully Conjugated Porphyrin-[36]Octaphyrin-Porphyrin Hybrid Tape Exhibiting Möbius Aromaticity

Akito Nakai; Takayuki Tanaka; Atsuhiro Osuka

doi:10.1002/chem.202200328

A Fully Conjugated Porphyrin-[36]Octaphyrin-Porphyrin Hybrid Tape Exhibiting Möbius Aromaticity

Chemistry. 2022 Apr 6;28(20):e202200328. doi: 10.1002/chem.202200328. Epub 2022 Mar 10.

Authors

Akito Nakai¹, Takayuki Tanaka¹, Atsuhiro Osuka¹

Affiliation

¹ Department of Chemistry, Graduate School of Science, Kyoto University Sakyo-ku, Kyoto, 606-8502, Japan.

PMID: 35218265
DOI: 10.1002/chem.202200328

Abstract

Directly meso-meso linked porphyrin-tetrabromo[36]octaphyrin-porphyrin hybrid trimer 10 was successfully synthesized via acid-catalyzed condensation reaction and subsequent oxidation. Zn^II -metalation of 10 induced transannular meso-meso bond formation to give Möbius aromatic bis-Zn^II octaphyrin 11, which was oxidized by DDQ/Sc(OTf)₃ to provide fully conjugated porphyrin-[36]octaphyrin-porphyrin hybrid tape 12 as the first example of porphyrin tape exhibiting Möbius aromaticity. Hybrid tape 12 displays significantly red-shifted absorption and small electrochemical HOMO-LUMO gap, indicating the effective conjugation through the whole chromophores.

Keywords: Möbius aromaticity; NIR absorption; expanded porphyrin; porphyrin tape; transannular bond formation.

Grants and funding

JP20K05463 and JP21H05480/Japan Society for the Promotion of Science