Ali Ebrahimi - Department of Chemistry, University of Sistan and Baluchestan, P.O. Box ۹۸۱۳۵–۶۷۴, Zahedan, Iran
Roya Behazin - Department of Chemistry, University of Sistan and Baluchestan, P.O. Box ۹۸۱۳۵–۶۷۴, Zahedan, Iran
Somayeh Abedini - Department of Chemistry, University of Sistan and Baluchestan, P.O. Box ۹۸۱۳۵–۶۷۴, Zahedan, Iran
Shiva Rezazadeh - Department of Chemistry, University of Sistan and Baluchestan, P.O. Box ۹۸۱۳۵–۶۷۴, Zahedan, Iran

The mutual relationship between cation-π and the individual hydrogen bond interactions in the cation∙∙∙adenine-thymine (Mz+∙∙∙A-T) complexes (Mz+= Li+, Na+, K+, Mg2+, Ca2+) have been studied at the MP2/6-311++G** level of theory. The cation-π and H-bonding interactions weaken each other. However, the cation-π interactions more influence the H-bondings. The effect of cation-π on the geometries and individual hydrogen bond (HB) energies of adenine-thymine (A-T) base pair have been investigated using electron charge densities calculated by the atoms in molecules (AIM) method at the hydrogen bond critical points (BCP). The results of AIM analysis are in good agreement with the calculated individual hydrogen bond energies. The cations with higher charge/radius (q/rad) ratio make more changes on the cation-π interactions, individual HB energies and the total binding energies of the A−T base pair.

H-bonding; cation-π; individual hydrogen bond; electron density; adenine; thymine