Structure and photochemistry of “bridged” bifunctional radical cations: Amidoesters vs. amides

Structure and properties of the radical cations of “bridged” amidoesters (functional groups separated by 0-4 methylene groups and the corresponding dimethyl-substituted amides) were investigated by EPR, optical absorption spectroscopy and DFT calculations. The EPR spectra and thermal reactions of these species are similar. Meanwhile, for amidoesters with 2-4 methylene groups, the methylene “bridge” is involved in photochemistry, which can be explained by specific conformation of amidoester radical cations determined by interaction between the functional groups.