One issue with many photocatalysts is their poor photostability under photoredox catalysis conditions. We thus undertook a comparative photostability study of mer-and fac-Ir(pmi)3 and fac-Ir(ppy)3 by measuring both the UV-Vis absorption and 1 H NMR spectra of these complexes before and after irradiation at each of 390 and 427 nm for 24 hours (Figure ). For each of the three PCs, a decrease in absorbance was observed after irradiation for 24 hours in MeCN. More striking is the significant change in the 1 H NMR spectrum of fac-Ir(ppy)3 following either 390 (Figure ) and 427 nm irradiation (Table of this complex in MeCN. Similarly, König and co-workers reported complete photodegradation of fac-Ir(ppy)3 in DCM after just six hours (λexc = 400 nm), while an improved stability was observed in toluene, with 40% of the PC remaining after 17 hours. A similar result was reported by Kuo and coworkers, suggesting that the nature of the solvent plays a significant role in the reaction outcome and solvent-specific photostability studies are warranted during reaction and photocatalyst development. The same sort of behavior was not observed with either of the Ir(pmi)3 isomers, and no photocatalyst degradation was observed for fac-Ir(pmi)3 (Figure ) by quantitative 1 H NMR spectroscopy (Table entry 2). For the mer-isomer, the 1 H NMR spectrum revealed some degradation (Figure ) while 57%