Electron attachment to oligonucleotide dimers in water: Microsolvation-assisted base-stacking forms
Jiande Gu, Yaoming Xie, Henry F. Schaefer III

The study of DNA subunit anions is an important recent chapter in the development of biophysical chemistry.
The dinucleoside phosphate dTpdA and dApdT systems are among the largest to be studied by reliable
theoretical methods. Exploring electron attachment to these subunits of DNA single strands enables
one to approach reliable predictions of the electron affinities of DNA single strands. DNA single strands
are found to have a strong tendency to host low-energy electrons and to form electronically stable radical
anions. The effect of base stacking and water-microsolvation in stabilizing the radical anions of the DNA
components is crucial. Aqueous solution dramatically increases the electron-capturing ability of the
water-microsolvated oligonucleotides, by up to 1 eV. The stable structures of the stacked bases suggest
that the H-bonding network through the microsolvating water molecules linking to the neighboring
bases might also be an important factor in the stabilization of the stacked bases.