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. 2022 Jan 24;2(2):407–418. doi: 10.1021/jacsau.1c00460

Figure 2.

Figure 2

Transient absorption (TA) spectroscopic studies. (a) TA spectra of photoexcited Ir2 at 23 °C in THF with λexc = 450 nm and pump power = 100 μW at 1 ps, 500 ps, 1.5 ns, and 6 ns. (b) Differential absorption spectrum of free Bq radical anion at 23 °C in THF collected by electrolysis at −2.3 V against Ag/AgCl electrode. Inset: absorption spectra of Bq•– in THF after 10, 20, 30, and 40 s of electrolysis. (c) DFT-computed spin density of Bq radical anion. (d) TA spectra of a mixture of 0.89 mM Ir2 and 74 mM Ant at 23 °C in THF with λexc = 450 nm and pump power = 100 μW at 1 ps, 100 ps, 300 ps, 500 ps, 1 ns, and 6 ns. Inset: kinetic traces of the same mixture at 425 (orange) and 530 nm (navy). (e) Stern–Volmer plot of Ir2 and Ant at 23 °C in THF. ktot = 1/τrise, kq, Ant = 6.8(3) × 109 M–1 s–1. (f) Comparison of TA spectrum of the mixture of 0.89 mM Ir2 and 74 mM Ant (black) with λexc = 450 nm at 2 ns delay and those of 112 mM Ant (orange) with λexc = 355 nm at 1 ns, 20 ns, 40 ns, 100 ns, 500 ns, 1 μs, 3 μs, 6 μs, 20 μs, and 80 μs at 23 °C in THF. Pump power = 100 μW. (g) Schematic description of the triplet–triplet EnT process between photoexcited Ir2 and Ant.