Document Type : Original Paper


Narges Bagheri*, Peyman Abbasi, Farhad Tavakkol Department of Chemistry, Islamic Azad University, Firoozabad Branch, Firoozabad, Iran


In this research, effects of Na+ ion on Nitrogenous Organic Bases (NOB) in the nucleic acids by using of a new index. This index is according to Electric Field Gradient (EFG) in the middle of bond and evaluated as a reference by corresponding cyclic same compounds. The studied molecules were Adenine, Guanine, Cytosine, Thymine and Uracil that has been investigated. The trend of changes of aromaticity by putting Na+ in the middle of cycle and change of distance according to degree of Angstrom (Å). It has been used Density Functional Theory (DFT) as a method for geometrical optimization Beck 3 Lee Yang Parr (B3LYP) in 6-311++G** and 6-31G standard basis set. These calculations have been done in two steps. In the first step, it has been calculated electric field gradient in the middle of bond in absence of Na+ (EFG0) and in the second step in presence of Na+, it has been calculated in 1Å distance of middle of bond without Na+ (EFG0.5) and with Na+ that compared amount of aromaticity between EFG0 and EFG0.5 in 6 distance (d = 0.5, 1, 1.5, 2, 2.5 and 3 Å).