Beckwith JS, Aster A, Vauthey E. The excited-state dynamics of the radical anions of cyanoanthracenes.
Phys Chem Chem Phys 2021;
24:568-577. [PMID:
34904984 PMCID:
PMC8694058 DOI:
10.1039/d1cp04014f]
[Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/29/2021] [Indexed: 12/03/2022]
Abstract
The radical anion of 9,10-dicyanoanthracene (DCA) has been suggested to be a promising chromophore for photoredox chemistry, due to its nanosecond excited-state lifetime determined from indirect measurements. Here, we investigate the excited-state dynamics of the radical anion of three cyanoanthracenes, including DCA˙-, produced by photoinduced electron transfer in liquid using both pump-probe and pump-pump probe transient electronic absorption spectroscopy. All three excited radical ions are characterised by a 3-5 ps lifetime, due to efficient non-radiative deactivation to the ground state. The decay pathway most probably involves D1/D0 conical intersection(s), whose presence is favoured by the enhanced flexibility of the radical anions relative to their neutral counterparts. The origin of the discrepancy with the nanosecond lifetime of DCA˙-* reported previously is discussed. These very short lifetimes limit, but do not preclude, photochemical applications of the cyanoanthracene anions.
Collapse