When EWGs are substituted, as in the case of -Cl and -F, the reduction potentials become more positive for both CV and DFT results (Figures ). This trend agrees with previous studies and is consistent with the electron density on the reduced quinones being more delocalised, making reduction more thermodynamically favourable. Positional effects observed in the experiments and calculations for the case of -Cl also agree: substitution at the 2-position shifts E • EE to a more positive value than at the 1-position. This trend is consistent with greater delocalisation of electron density when Cl is substituted at the 2-position with a larger LUMO coefficient in Q (Figure ). The largest shift of 0.4 V due to multiple substitution in the case of octafluoroanthraquinone AQ-F 8 is also well predicted by DFT.