The Hauer group presents smoking-gun evidence for radical ion-substrate preassembly by transient absorption spectroscopy (TAS)! Our triarylaminium radical cationic photocatalysts are excited to a higher-than-first excited state, which decays with two components: 1 ps 'fast decay' and 5 ps 'slow decay'. The latter represents the decay of the first excited state, and is unaffected by presence of arene substrate. The former however, is quenched by ~60% in the presence of arene - confirming 'anti-Kasha' behavior and preassembly on this timescale far too short for diffusion.
We're excited by the implications this has for leveraging preassemblies for beating internal conversion and accessing the photochemistry of higher excited states!
While Shangze and JPB contributed to the case study, the main advance of this paper is actually development of a novel TAS technique, and full credit (and questions ;-) for that go to J. Hauer and A. Kumar.
Congrats to the team!
\(^(I)^)/
Comentarios