Conclusion
For A–G mispairs, two preferred tautomeric forms are considered, that is, AantiGanti and AsynGanti mispairs. The interaction of Li+, Na+ and K+cations with Aanti-Ganti and Asyn-Ganti mispairs are investigated at the MP2/6-311++G(d,p) level of theory. The natural bond orbital (NBO) method as well as the quantum theory of atoms in molecules (AIM) is applied to characterize hydrogen bond interactions in the considered systems. For each ion type, , the most stable complex in AantiGanti and AsynGanti configurations is related to binding cation to N3 atom of guanine and N1 atom of adenine, respectively.
In general, the AantiGanti configuration is more stable than AsynGanti one. The strength of the hydrogen bonds generally correlate well with the type and position of cations. Also, the absolute values of hydrogen bonding intermolecular energies, was calculated using EML formula, in AantiGanti mismatch are higher than AsynGanti ones. In general, the length of HB1 and HB2 in AsynGanti are greater than corresponding in AantiGantimispair. The results indicate that the values of E(2)and ρ(r) at the BCP of the hydrogen bond in AantiGanti are greater than corresponding in AsynGanti mispair. Also, that the maximum value of the ρ(r) is related to highest absolute value of corresponding EEML for each hydrogen bond and vice versa.