Fig. 3: Screening of in-cage reverse electron transfer parameters.
From: Cage escape governs photoredox reaction rates and quantum yields
a, Reorganization energies for given ratios of electronic couplings able to produce krET,calc.(Ru)/krET,calc.(Cr) ratios (equation (3)) in line with the experimental krET,exp.(Ru)/krET,exp.(Cr) ratios derived from equation (2). The distribution here is shown for specific coupling ratios over the applied donors. b, Reorganization energies found for the individual donors based on the analysis in a (Supplementary Table 3). The distribution here is shown for specific donors over the considered coupling ratios. In a, the data size (n) for each distribution is 12 (for 12 applied donors) and in b, the data size is 14 (HAB ratios from 0.3 to 1.6 eV in increments of 0.1 eV). The grey boxes in a and b contain the middle 50% of data, the so-called interquartile range (IQR). The whisker boundaries are drawn at the most extreme data point that is no more than ±1.5IQR from the top and bottom edges of the box53. The horizontal black lines in the boxes mark the median values, and the open squares represent the average values. c, Correlation between the calculated and experimental ratios of the rate constants for in-cage reverse electron transfer. In total, 2,184 combinations of HAB(Ru)/HAB(Cr) and λ (Supplementary Table 5) were considered (grey squares, right-hand y axis), of which 63 (Supplementary Table 4) provided agreement between calculation and experiment within a deviation of 15% (black circles, left-hand y axis). The numbers shown in c correspond to the donors 1–12. d, Generic Marcus parabola illustrating the dependence of the rate constant for in-cage reverse electron transfer (krET) on its driving force (ΔGrET). For a given electron donor, in-cage reverse electron transfer with the reduced RuII complex (black square) occurs more deeply in the inverted regime and thus is slower than in-cage reverse electron transfer with the reduced CrIII complex (black circle).
