813987.fig.002
Figure 2: Schematic plot of free energy along the reaction pathway (A* + D A*D (loose pair of reactants) A-z D+z (transition state or exciplex) A•-D•+ (solvent separated ion pair) A•- + D•+) blue line—for long-range mechanism ((2), 𝜆 = 2 . 0  eV, Δ 𝐺 E T = 0 . 5  eV); and red line—for transient exciplex mechanism ( Δ 𝐺 E x = 0 . 1 5  eV) for isoenergetic ET reaction ( Δ 𝐺 E T = 0 ) in butyronitrile ( Δ 𝐺 D i = 0 . 1 4  eV). Experimental data on Δ 𝐺 1 , Δ 𝐺 E x , Δ 𝐺 E x along the reaction coordinate: green squares—for 9-cyanoanthracene* + 1, 8-dimethylnaphthalene in MeCN ( Δ 𝐺 E T = 0 . 1  eV); dark cyan rhombs—in PrCN ( Δ 𝐺 E T = 0 . 0 1  eV); magenta triangles—for 9-cyanophenanthrene + 1, 2-dimethoxylbenzene in PrCN ( Δ 𝐺 E T = 0 . 1  eV) [15]; black circles—for 1, 2, 4, 5-tetracyanobenzene* + durene in 1, 2-dichloroetane (according to the experimental data [27, 28], Δ 𝐺 E T 0 . 5  eV).