Substituent effect of halogen (F, Cl and Br) on uracil tetrad: A theoretical study

In this paper, the substituted uracil tetrad XU4 (X=F, Cl and Br) where X replace the H atoms at five sites of uracils have been investigated using density functional theory method. Geometries, energies and electrostatic potential energy surfaces have been discussed in detail. The outcomes show that when XU take place of U, the preferred symmetry of the tetrad changed from C4 to S4. Stabilization energies indicate that the XU substituted tetrads becomes more and more unstable as from F to Br. ESP maps suggest that U4 could bind a cation while XU4 could not. All the tetrads adopt a nonplanar structure that is not suitable for stacking.