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Donor–Donor′–Acceptor Triads Based on [3.3]Paracyclophane with a 1,4‐Dithiafulvene Donor and a Cyanomethylene Acceptor: Synthesis, Structure, and Electrochemical and Photophysical Properties
Author(s) -
Sako Katsuya,
Hasegawa Tomoya,
Onda Hiroyuki,
Shiotsuka Michito,
Watanabe Motonori,
Shinmyozu Teruo,
Tojo Sachiko,
Fujitsuka Mamoru,
Majima Tetsuro,
Hirao Yasukazu,
Kubo Takashi,
Iwanaga Tetsuo,
Toyota Shinji,
Takemura Hiroyuki
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201801774
Subject(s) - moiety , chemistry , radiolysis , radical ion , acceptor , photochemistry , delocalized electron , dication , electrochemistry , crystallography , ion , stereochemistry , radical , organic chemistry , physics , electrode , condensed matter physics
Donor–donor′–acceptor triads ( 1 , 2 ), based on [3.3]paracyclophane ([3.3]PCP) as a bridge, with electron‐donating properties (D′) using 1,4‐dithiafulvene (DTF; TTF half unit) as a donor and dicyanomethylene (DCM; TCNE half unit) or an ethoxycarbonyl‐cyanomethylene (ECM) as an acceptor were designed and synthesized. The pulse radiolysis study of 1 a in 1,2‐dichloroethane allowed the clear assignment of the absorption bands of the DTF radical cation ( 1 a .+ ), whereas the absorption bands due to the DCM radical anion could not be observed by γ‐ray radiolysis in 2‐methyltetrahydrofuran rigid glass at 77 K. Electrochemical oxidation of 1 a first generates the DTF radical cation ( 1 a .+ ), the absorption bands of which are in agreement with those observed by a pulse radiolysis study, followed by dication ( 1 a 2+ ). The ESR spectrum of 1 a .+ showed a symmetrical signal with fine structure and an ESR simulation predicted that the spin of 1 a .+ is delocalized over S and C atoms of the DTF moiety and the central C atom of the trimethylene bridge bearing the DTF moiety. Pulse radiolysis, ESR, and electrochemical studies indicate that the DTF radical cation of 1 a .+ is more stable than that of 6 .+ , and the latter shows a strong tendency to dimerize. This result indicates that the [3.3]PCP moiety as a bridge can stabilize the DTF radical cation more than the 1,3‐diphenylpropane moiety because of kinetic stability due to its rigid structure and the weak electronic interaction of DTF and DCM moieties through [3.3]PCP.