Photoinduced Charge Migration in the Picosecond Regime for Thianthrene-Linked Acridinium Ions

Abstract

The thianthrene ring system has a novel redox chemistry that has been the subject of study for three decades. The sulfur heterocycle undergoes a reversible on-electron oxidation (E{sub 1/2} = 1.23 vs SCE, CH{sub 3}CN), yielding a radical cation species that is stable enough to be isolated for independent investigation; magnetic resonance studies on the cation have included ESR, ENDOR, and CIDEP measurements. Photoinduced electron transfer involving thianthrene (TH) as an electron donor has been studied, including a report of trapping of the radical cation. As part of a study of linked donor-acceptor systems that employ the acridinium ion as electron acceptor, the authors have prepared the first linked thianthrenes appropriate for investigation of intramolecular electron transfer involving TH as an electron donor. Principal findings include the observation of very fast forward and back electron transfer (charge shift, CSH) in the picosecond time domain involving TH and acridinium subunits.