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Intramolecular Charge Transfer in Kekulé‐ and Non‐Kekulé‐Bridged Bis(triarylamine) Radical Cations: Missing Key Compounds in Organic Mixed‐Valence Systems
Author(s) -
Uebe Masashi,
Ito Akihiro
Publication year - 2019
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201900036
Subject(s) - intramolecular force , chemistry , valence (chemistry) , radical ion , electronic structure , molecule , bridging (networking) , photochemistry , electron transfer , computational chemistry , stereochemistry , ion , organic chemistry , computer network , computer science
Abstract From the viewpoint of para ‐ meta topological bridging effect on the electronic coupling in organic mixed‐valence (MV) systems, the optically induced and thermally assisted intramolecular charge/spin transfer (ICT/IST) processes have been investigated for three bis(triarylamine) (BTA) radical cations as missing key compounds in very basic BTA MV systems. In contrast to the case of p ‐ and m ‐dinitrobenzene radical anions, the difference in the strength of electronic coupling ( V ) was not so large for the present BTA MV radical cations, although they still fall within the paradigm of strong V for para ‐linkage and weak V for meta ‐linkage. Unexpectedly, it has been found that meta ‐phenylenediamine radical cation has an electronic coupling comparable to those in the para ‐conjugated BTA‐based MV species, and the ICT/IST rate exceeds the ESR time‐scale. This finding is very encouraging considering that sufficient electronic communication can be ensured even when the redox‐active centers are linked directly by the meta ‐phenylene bridge, thus broadening the selection of π‐bridging units for molecule‐based optoelectronics.