Laser Flash Photolysis and Product Studies of the Photoionization of N-Methylacridan in Aqueous Solution

Article abstract of DOI:10.1021/j100178a005

Photolysis of N-methylacridan (1) in deaerated aqueous CH3CN solution results in photoionization, to give the N-methylacridan radical cation (1^.+) as the first-formed intermediate.Subsequent deprotonation from 1^.+ gives N-methylacridyl (1^.), which dimerizes to give 9,9'-bis(N-methylacridyl) (2) as the only isolable product.Quantum yields for loss of 1 are 0.085 and 0.022 in 1:1 H2O-CH3CN and 100percent CH3CN, respectively.In the presence of oxygen, 1^. is believed to be oxidized further (electron transfer to O2), to give N-methylacridinium ion (4), which was detected by its characteristic UV absorption and fluorescence emission spectra.Laser flash photolysis studies provide direct evidence for photoionization of 1 to give the radical cation 1^.+ which subsequently deprotonates to form 1^..The combined transient and product studies indicate a monophotonic mechanism from the first excited state.The results demonstrate that photoexcited 1 is an excellent electron donor to bulk solvent.The process does not require externally added electron acceptors for photoredox chemistry.