We have developed a set of N-cyclopropylaniline (CPA) analogs to probe the oxidative properties of triplet-state photosensitizers in aqueous solutions. After an initial single electron transfer (SET) oxidation, anilines without a cyclopropyl group are susceptible to radical cation quenching by antioxidant moieties present in DOM, causing an underestimation in the rate of oxidation during steady-state experiments. In this work, we show that CPAs undergo a spontaneous, irreversible ring-opening reaction after an initial SET, which was found to outcompete antioxidant quenching. Outcomes of this work, including CPA bimolecular rate constants, CPA·+ lifetimes, and identified ring-opened products, support the usefulness of N-cyclopropylanilines as steady-state SET probes in photosensitized aqueous solutions.
Development of N-Cyclopropylanilines to Probe the Oxidative Properties of Triplet-State Photosensitizers
Nicholas C. Pflug, Markus Schmitt and Kristopher McNeill*
Environ. Sci. Technol. 2019 https://pubs.acs.org/doi/10.1021/acs.est.9b00416