In 2022,Earley, J. D.; Zieleniewska, A.; Ripberger, H. H.; Shin, N. Y.; Lazorski, M. S.; Mast, Z. J.; Sayre, H. J.; McCusker, J. K.; Scholes, G. D.; Knowles, R. R.; Reid, O. G.; Rumbles, G. published an article in Nature Chemistry. The title of the article was 《Ion-pair reorganization regulates reactivity in photoredox catalysts》.Electric Literature of C18H12Br3N The author mentioned the following in the article:
Cyclometalated and polypyridyl complexes of d6 metals are promising photoredox catalysts, using light to drive reactions with high kinetic or thermodn. barriers via the generation of reactive radical intermediates. However, while tuning of their redox potentials, absorption energy, excited-state lifetime and quantum yield are well-known criteria for modifying activity, other factors could be important. Here we show that dynamic ion-pair reorganization controls the reactivity of a photoredox catalyst, [Ir[dF(CF3)ppy]2(dtbpy)]X. Time-resolved dielec.-loss experiments show how counter-ion identity influences excited-state charge distribution, evincing large differences in both the ground- and excited-state dipole moment depending on whether X is a small associating anion (PF6-) that forms a contact-ion pair vs. a large one that either dissociates or forms a solvent-separated pair (BArF4-). These differences correlate with the reactivity of the photocatalyst toward both reductive and oxidative electron transfer, amounting to a 4-fold change in selectivity toward oxidation vs. reduction These results suggest that ion pairing could be an underappreciated factor that modulates reactivity in ionic photoredox catalysts. In the experiment, the researchers used Tris(4-bromophenyl)amine(cas: 4316-58-9Electric Literature of C18H12Br3N)
In other references, Tris(4-bromophenyl)amine(cas: 4316-58-9) is often used in the synthesis of porous luminescent covalent–organic polymers (COPs)Electric Literature of C18H12Br3N
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary