Results and discussion
Molecular electrostatic potential maps (MEPs) are very helpful in identifying the electron deficient and electron rich areas in molecules and have been employed extensively in several studies [11. Mottishaw, J. D., Erck, A. R., Kramer, J. H., Sun, H., Koppang, M.J. Chem. Educ . 2015 , 92, 1846–1852.,22. Khan, I., Panini, P., Ud-Din Khan, S., Rana, U. A., Andleeb, H., Chopra, D., Hameed, S., Simpson, J. Cryst. Growth Des .2016 , 16, 1371–1386.]. The molecular electrostatic potentials have been calculated to investigate the influence of cation binding on the properties of hydrogen bonds in considered systems. Figure 1 show electrostatic potential map for isolated adenine and guanine. One can see that the basins of negative potential are located around N3 and N7, and O6 atoms of guanine and N3 and N7, and N1 atoms of adenine.