Guanine tetrad interacting with divalent metal ions (MÂ =Â Fe2+, Co2+, Ni2+, Cu2+ and Zn2+): A density functional study

The guanine tetrad(G4) and transition metal cation(M) complex has been studied using density functional method at B3LYP/6-31G(d) level. The outcomes show that the stability sequence (BSSE corrected) of G4-M is Ni2+ > Cu2+ > Co2+ > Fe2+ > Zn2+, while after hydration energy correction it changes to Ni2+ > Fe2+ > Co2+ > Cu2+ > Zn2+, and that of the model including two water molecules is Co2+ > Fe2+ > Ni2+ > Cu2+ > Zn2+. AIM analysis shows good correlation of the values of electron density and its Laplacian at the bond critical points with the hydrogen bond length in the tetrads.