Substituent group effects on reorganization and activation energies: Theoretical study of charge transfer reaction through DNA

The density functional theory (DFT) calculations (B3LYP) with aug-cc-pVDZ basis sets on various substituted neutral and radical cationic guanine-cytosine (GC^*+) base pairs suggest that an electron-withdrawing ring deactivating substituent group like -NO₂, -COOH attached to a G ring lowers the reorganization/activation energy values whereas an electron releasing ring activating group like -OH increases these values. An electron releasing, but a ring deactivating group -F, exhibits its effect in between the above two extreme cases. A weak electron releasing, ring activating methyl group, as well as substituent groups attached to C (cytosine)-ring show almost no effect.