Diarylamine-fused subporphyrins 1 a and 1 b were synthesized from β,β-diiodo-meso-chloro subporphyrin 2 through a one-pot procedure involving nucleophilic aromatic substitution and SRN1-type intramolecular fusion reaction as the first example of meso-nitrogen-embedded subporphyrin. While non-fused counterparts 3 b and 4 b display effective fluorescence quenching due to twisted intramolecular charge transfer (TICT) in CH2Cl2 at room temperature, 1 b emits fluorescence with ΦF=0.18 under the same conditions, because conformational twisting is not allowed due to the fused structure. In addition, the oxidative titration with tris(4-bromophenyl)ammoniumyl hexachloroantimonate gave cation radical 7 for 1 a and cation radical and dication for 1 b. Actually, cation radical 7 was isolated through separation over silica gel column but was found to slowly decompose in concentrated solutions.
Bibliographical noteFunding Information:
This work was supported by JSPS KAKENHI Grant Numbers 25220802 and 16K13952. N.F. and D.S. acknowledge a JSPS Fellowship for Young Scientists. The work at Yonsei was supported by the Global Research Laboratory (GRL) Program funded by the Ministry of Science, ICT & Future, Korea (2013K1A1A2A02050183). We appreciate kind supports of Prof. Dr. Takahisa Ikeue (Shimane University) for ESR measurement.
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All Science Journal Classification (ASJC) codes
- Organic Chemistry