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Benzo‐Tetrathiafulvalene‐ (BTTF‐) Annulated Expanded Porphyrins: Potential Next‐Generation Multielectron Reservoirs
Author(s) -
Jana Atanu,
Ishida Masatoshi,
Furuta Hiroyuki
Publication year - 2021
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.202005021
Subject(s) - intramolecular force , tetrathiafulvalene , homo/lumo , chemistry , electrochemistry , photochemistry , porphyrin , electron transfer , conformational isomerism , steric effects , stereochemistry , molecule , organic chemistry , electrode
Two sterically crowded benzo‐tetrathiafulvalene (BTTF)‐annulated expanded porphyrins ( BTTF7‐F and BTTF8 ) are synthesized. Detailed photophysical investigations reveal their intrinsic intramolecular charge transfer (CT) character, originated from partial electron transfer from electron‐rich TTF units to the relatively electron‐deficient macrocyclic core. This finding stands in contrast to what was observed in the previously reported Figure‐of‐eight conformer of BTTF‐annulated [28]hexaphyrin ( BTTF6 ), in which a typical π–π* electronic transition from HOMO to LUMO was observed. However, core expansion in BTTF7‐F and BTTF8 makes the oligopyrrole macrocyclic cores relatively more electron‐deficient, facilitating the effective intramolecular CT process. Comparative electrochemical investigations reveal that the current generated at the oxidative region is directly proportional to the number of TTF units attached to the macrocyclic core. This work demonstrates the control of the intramolecular CT process through incremental addition of TTF units to the macrocyclic core. Facile multielectron electrochemical oxidations of these expanded porphyrins suggest that they behave like potential multielectron reservoirs.