Figure 4.

The electron transfer rate k_AB⁽¹⁾ as a function of redox free energy (driving force) for electron transfer (data from the second and seventh columns of Table 1). The solid line gives a best fit to the data. The dashed line represents the dependence predicted by the Marcus theory for an electron transfer limited reaction using the measured free energy difference between the initial, Q_A^−⋅Q_B, and final, Q_AQ_B^−⋅, states of 60 meV (19) and 1.1 eV for the reorganization energy (13, 31). Error bars represent one SD of the mean. Quinones incorporated into the Q_A site listed in order of decreasing redox potential were: 1, MQ₀; 2, Q₁₀; 3, MQ_P; 4, MQ₄; 5, Me₃NQ; and 6, Me₄NQ. Redox energies are quoted with respect to Q₁₀ (see • without error bars).