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

Nonconventional Hydrogen Bonds: A Theoretical Study of [uracil-L]−(L = F, Cl, Br, I, Al, Ga, In) Complexes

“…Despite the importance of the effects that halogens can have on the stability of nitrogen bases, little is known concerning the interaction of DNA nitrogen bases with halogen atoms. Structures and properties of halouracils (halogen replaces the H atoms at five sites of uracil) were reported previously, but there is little knowledge concerning the interaction of halogen atoms with nitrogen bases, specifically in the anionic state. For halouracils, the compounds adopt a nonplanar structure that is not suitable for stacking, and halogen substitution has a smaller effect on the ionization energy than the electron affinity of uracil.…”

Nucleic Acid G-quartets: Insights into Diverse Patterns and Optical Properties

“…All structures are optimized by density functional theory (DFT) . The DFT calculations are carried out with nonlocal hybrid three-parameter Lee–Yang–Parr (B3LYP) , level of theory with the 6-31G(d) − basis set as implemented in the Gaussian 09 program. Meng et al have studied the structure and stability of G4-complexes at B3LYP level using 6-31G(d) and 6-31G(d,p) basis sets.…”