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.